Power device

1. Field of the Invention

The present invention relates to a power device. Priority is claimed on Japanese Patent Application No. 2013-119938, filed Jun. 6, 2013, the content of which is incorporated herein by reference.

2. Description of Related Art

A power system which includes a DC-DC converter, two switches including first and second switches, and two power sources including first and second power sources has been known. The power system switches between a serial connection state where the first and second power sources are connected in series and a parallel connection state where the first and second power sources are connected in parallel based on ON/OFF state of the first and second switches, and connects the first and second power sources in the serial connection state or the parallel connection state with an electrical load, while the power system adjusts a voltage applied to the electrical load using the DC-DC converter (for example, refer to Japanese Unexamined Patent Application, First Publication No. 2012-152079).

A power device which includes a step-up converter, four relays including first to fourth relays, and two secondary batteries has been known. The power device switches between a serial connection state where the two secondary batteries are connected in series and a parallel connection state where the two secondary batteries are connected in parallel based on ON/OFF state of the first to fourth relays, and connects the two secondary batteries in the serial connection state or the parallel connection state with an electrical load, while the power device adjusts a voltage applied to the electrical load using the step-up converter (for example, refer to Japanese Unexamined Patent Application, First Publication No. 2012-60838).

Operating points of the DC-DC converter (or the step-up converter) in the power system and power device of the related art described above are substantially limited to only two points including a first point where the first and second power sources (or secondary batteries) are connected in parallel and the step-up ratio is one and a second point where the first and second power sources (or the secondary batteries) are connected in series and the step-up ratio is two. Therefore, if the power system and power device are part of a vehicle, for example, from a small car to a large car, and the voltage is arbitrarily controlled to be in a desire voltage range, it is necessary to change characteristics of a power source or a voltage control device. Therefore, it is difficult to ensure the general versatility of the power system and power device.

The present invention provides a power device where the adjustable voltage range is large, and thereby, the general versatility is improved.

(1) According to one aspect of the present invention, a power device may include at least three power sources which are a first power source, a second power source, and a third power source, a load which is configured to be driven by a power supplied from the power source, and a voltage control unit which is configured to control a voltage to be applied to the load. The voltage control unit may include several electrical potential points, and at least two converter circuits which are a first converter circuit and a second converter circuit. The several electrical potential points may include a first electrical potential point connected with a negative electrode of the first power source, a second electrical potential point connected with a positive electrode of the first power source, a third electrical potential point connected with a negative electrode of the second power source, a fourth electrical potential point connected with a positive electrode of the second power source, a fifth electrical potential point connected with a negative electrode of the third power source, and a sixth electrical potential point connected with a positive electrode of the third power source. The first converter circuit may be connected with the first electrical potential point, the second electrical potential point, the third electrical potential point, and the fourth electrical potential point. The second converter circuit may be connected with the third electrical potential point, the fourth electrical potential point, the fifth electrical potential point, and the sixth electrical potential point. The first converter circuit may be configured to at least one of (a) control a voltage, applied between the first electrical potential point and the fourth electrical potential point, to be within a range from a voltage of the first power source or a voltage of the second power source to a summed voltage of the voltage of the first power source and the voltage of the second power source, and (b) control the voltage, applied between the first electrical potential point and the fourth electrical potential point, to be equal to or more than the summed voltage of the voltage of the first power source and the voltage of the second power source. The second converter circuit may be configured to at least one of (a) control a voltage, applied between the third electrical potential point and the sixth electrical potential point, to be within a range from the voltage of the second power source or a voltage of the third power source to a summed voltage of the voltage of the second power source and the voltage of the third power source, and (b) control the voltage, applied between the third electrical potential point and the sixth electrical potential point, to be equal to or more than the summed voltage of the voltage of the second power source and the voltage of the third power source.

(2) According to another aspect of the present invention, a power device may include N power sources which are first to N-th power sources, where N is a natural number which is equal to or more than 3, a load which is configured to be driven by a power supplied from the power source, and a voltage control unit which is configured to control a voltage to be applied to the load. The voltage control unit may include (2N) electrical potential points which are first to (2N)-th electrical potential points, and (N−1) converter circuits which are first to (N−1)-th converter circuits. A negative electrode of the K-th power sources may be connected to the (2K−1)-th electrical potential point, where K is an arbitrary natural number which is equal or less than N. A positive electrode of the K-th power sources may be connected to the (2K)-th electrical potential point. The L-th converter circuit may be connected to the (2L−1)-th to (2L+2)-th electrical potential points, where L is an arbitrary natural number which is equal or less than (N−1). The L-th converter circuit may be configured to at least one of control a voltage, applied between the (2L−1)-th electrical potential point and the (2L+2)-th electrical potential point, to be within a range from a voltage of the L-th power source or a voltage of the (L+1)-th power source to a summed voltage of the voltage of the L-th power source and the voltage of the (L+1)-th power source, and control the voltage, applied between the (2L−1)-th electrical potential point and the (2L+2)-th electrical potential point, to be equal to or more than the summed voltage of the voltage of the voltage of the L-th power source and the voltage of the (L+1)-th power source.

(3) In the (2) described above, the power device may further include a second load which is connected with at least one of the first to (N−1)-th converter circuits.

(4) In the (2) or (3) described above, the power device may further include a third load which is connected with at least one of the first to N-th power sources in parallel.

(5) In one of the (2) to (4) described above, the power device may further include a fourth load having a first end and a second end. The first end of the fourth load may be connected with a first of a pair among the first to (2N)-th electrical potential points, and the second end of the fourth load may be connected with a second of the pair.

According to the aspect in the (1) or (2) described above, the power device can sequentially perform any voltage control within a desired voltage range from any one of the first voltage of the first power source, the second voltage of the second power source, and the third voltage of the third power source to a voltage which is equal to or more than the summed voltage of the first voltage of the first power source, the second voltage of the second power source, and the third voltage of the third power source. For example, the power device can be adapted easily to various systems by setting the number of the power sources and the number of the converter circuits which are adapted to the desired voltage range when the power device is designed. Therefore, the controllable voltage range is enlarged, and thereby the general versatility can be improved.

Furthermore, in the (3) described above, each voltage to be applied to the load and voltage to be applied to the second load can be arbitrarily controlled. Therefore, the general versatility with regard to the application to various systems can be improved.

Furthermore, in the (4) described above, each voltage to be applied to the load and voltage to be applied to the third load can be arbitrarily controlled. Therefore, the general versatility with regard to the application to various systems can be improved.

Furthermore, in the (5) described above, each voltage to be applied to the load and voltage to be applied to the fourth load can be arbitrarily controlled. Therefore, the general versatility with regard to the application to various systems can be improved.

FIG. 1 is a configuration diagram showing a power device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a power device according to a first variation of the embodiment of the present invention.

FIG. 3A is a diagram showing a main configuration of the power device according to the first variation of the embodiment of the present invention.

FIG. 3B is a diagram showing a main configuration of the power device according to the first variation of the embodiment of the present invention.

FIG. 4 is a configuration diagram showing a power device according to a second variation of the embodiment of the present invention.

FIG. 5 is a configuration diagram showing a power device according to a third variation of the embodiment of the present invention.

FIG. 6 is a configuration diagram showing a power device according to a fourth variation of the embodiment of the present invention.

FIG. 7 is a configuration diagram showing a power device according to a first example of the embodiment of the present invention.

FIG. 8A is a configuration diagram showing a converter circuit according to the first example of the embodiment of the present invention.

FIG. 8B is a configuration diagram showing a converter circuit according to the first example of the embodiment of the present invention.

FIG. 9A is a diagram showing ON/OFF of each switching device and a current flow when the converter circuit according to the first example of the embodiment of the present invention is in a power mode.

FIG. 9B is a diagram showing ON/OFF of each switching device and a current flow when the converter circuit according to the first example of the embodiment of the present invention is in a regenerative mode.

FIG. 10 is a configuration diagram showing a power device according to a second example of the embodiment of the present invention.

FIG. 11A is a configuration diagram showing a converter circuit according to the second example of the embodiment of the present invention.

FIG. 11B is a configuration diagram showing a converter circuit according to the second example of the embodiment of the present invention.

FIG. 12A is a diagram showing ON/OFF of each switching device and a current flow when the converter circuit according to the second example of the embodiment of the present invention is in a power mode.

FIG. 12B is a diagram showing ON/OFF of each switching device and a current flow when the converter circuit according to the second example of the embodiment of the present invention is in a regenerative mode.

FIG. 13 is a configuration diagram showing a converter circuit according to a third example of the embodiment of the present invention.

FIG. 14A is a diagram showing ON/OFF of each switching device and a current flow when the converter circuit according to the third example of the embodiment of the present invention is in a power mode.

FIG. 14B is a diagram showing ON/OFF of each switching device and a current flow when the converter circuit according to the third example of the embodiment of the present invention is in a regenerative mode.

FIG. 15 is a configuration diagram showing a converter circuit according to a fourth example of the embodiment of the present invention.

FIG. 16A is a diagram showing ON/OFF of each switching device and a current flow when the converter circuit according to the fourth example of the embodiment of the present invention is in a power mode.

FIG. 16B is a diagram showing ON/OFF of each switching device and a current flow when the converter circuit according to the fourth example of the embodiment of the present invention is in a regenerative mode.

FIG. 16C is a diagram showing ON/OFF of each switching device and a current flow when the converter circuit according to the fourth example of the embodiment of the present invention is in a power mode.

FIG. 16D is a diagram showing ON/OFF of each switching device and a current flow when the converter circuit according to the fourth example of the embodiment of the present invention is in a regenerative mode.

FIG. 17 is a configuration diagram showing a converter circuit according to a fifth example of the embodiment of the present invention.

FIG. 18A is a diagram showing ON/OFF of each switching device and a current flow when the converter circuit according to the fifth example of the embodiment of the present invention is in a power mode.

FIG. 18B is a diagram showing ON/OFF of each switching device and a current flow when the converter circuit according to the fifth example of the embodiment of the present invention is in a regenerative mode.

FIG. 19 is a configuration diagram showing a converter circuit according to a sixth example of the embodiment of the present invention.

FIG. 20 is a configuration diagram showing a converter circuit according to a sixth example of the embodiment of the present invention.

FIG. 21A is a diagram showing ON/OFF of each switching device and a current flow when the converter circuit according to the sixth example of the embodiment of the present invention is in a power mode.

FIG. 21B is a diagram showing ON/OFF of each switching device and a current flow when the converter circuit according to the sixth example of the embodiment of the present invention is in a regenerative mode.

FIG. 21C is a diagram showing ON/OFF of each switching device and a current flow when the converter circuit according to the sixth example of the embodiment of the present invention is in a power mode.

FIG. 21D is a diagram showing ON/OFF of each switching device and a current flow when the converter circuit according to the sixth example of the embodiment of the present invention is in a regenerative mode.

FIG. 22 is a configuration diagram showing a converter circuit according to a seventh example of the embodiment of the present invention.

FIG. 23A is a diagram showing ON/OFF of each switching device and a current flow when the converter circuit according to the seventh example of the embodiment of the present invention is in a power mode.

FIG. 23B is a diagram showing ON/OFF of each switching device and a current flow when the converter circuit according to the seventh example of the embodiment of the present invention is in a regenerative mode.

FIG. 23C is a diagram showing ON/OFF of each switching device and a current flow when the converter circuit according to the seventh example of the embodiment of the present invention is in a power mode.

FIG. 23D is a diagram showing ON/OFF of each switching device and a current flow when the converter circuit according to the seventh example of the embodiment of the present invention is in a regenerative mode.

Hereinafter, a power device according to an embodiment of the present invention will be described with reference to the attached drawings.

The power device according to the embodiment of the present invention provides a direct-current power to a load such as an inverter. The inverter controls the power mode and the regenerative mode of an electric motor which can produce, for example, a drive force to run a vehicle.

As illustrated in FIG. 1 , a power device 10 according to the embodiment of the present invention includes a first power source BT 1 , a second power source BT 2 , and a third power source BT 3 , such as a battery, a first converter circuit (CV 1 ) 11 , a second converter circuit (CV 2 ) 12 , a load (LD) 13 , a capacitor (CA) 14 , and a control device 15 . The load 13 can drive using a direct-current power supplied from the first and second converter circuits 11 and 12 , and supply a generated direct-current power to the first and second converter circuits 11 and 12 . The capacitor (CA) 14 is connected with both ends of the load 13 .

The power device 10 includes a first electrical potential point P 1 to a sixth electrical potential point P 6 .

The first electrical potential point P 1 is connected with a negative electrode of the first power source BT 1 , and the second electrical potential point P 2 is connected with a positive electrode of the first power source BT 1 . The third electrical potential point P 3 is connected with a negative electrode of the second power source BT 2 , and the fourth electrical potential point P 4 is connected with a positive electrode of the second power source BT 2 . The fifth electrical potential point P 5 is connected with a negative electrode of the third power source BT 3 , and the sixth electrical potential point P 6 is connected with a positive electrode of the third power source BT 3 .

The first converter circuit 11 is connected with the first electrical potential point P 1 , the second electrical potential point P 2 , the third electrical potential point P 3 , and the fourth electrical potential point P 4 , and the second converter circuit 12 is connected with the third electrical potential point P 3 , the fourth electrical potential point P 4 , the fifth electrical potential point P 5 , and the sixth electrical potential point P 6 .

As discussed later, the first and second converter circuits 11 and 12 include at least step-down or step-up direct-current power converter circuit, and are controlled based on signals output from the control device 15 so that the first and second converter circuits 11 and 12 can drive independently from each other.

The first converter circuit 11 controls a voltage, applied between the first electrical potential point P 1 and the fourth electrical potential point P 4 , to be within a range from a first voltage VB1 of the first power source BT 1 or a second voltage VB2 of the second power source BT 2 to a summed voltage (VB1+VB2) of the first voltage VB1 of the first power source BT 1 and the second voltage VB2 of the second power source BT 2 , and/or controls the voltage, applied between the first electrical potential point P 1 and the fourth electrical potential point P 4 , to be equal to or more than the summed voltage (VB1+VB2) of the first voltage VB1 of the first power source BT 1 and the second voltage VB2 of the second power source BT 2 .

The second converter circuit 12 controls a voltage, applied between the third electrical potential point P 3 and the sixth electrical potential point P 6 , to be within a range from a second voltage VB2 of the second power source BT 2 or a third voltage VB3 of the third power source BT 3 to a summed voltage (VB2+VB3) of the second voltage VB2 of the second power source BT 2 and the third voltage VB3 of the third power source BT 3 , and/or controls the voltage, applied between the third electrical potential point P 3 and the sixth electrical potential point P 6 , to be equal to or more than the summed voltage (VB2+VB3) of the second voltage VB2 of the second power source BT 2 and the third voltage VB3 of the third power source BT 3 .

The control device 15 includes a load control unit 21 and a connection switching control unit 22 .

The load control unit 21 controls the operation of the load 13 . For example, if the load 13 includes an electric motor such as a three-phase brushless DC motor and an inverter to control the power mode and regenerative mode of the electric motor, the load control unit 21 controls a power conversion operation of the inverter. In detail, when the electric motor is in a power mode, the load control unit 21 converts a direct-current power applied between both electrodes at the direct current side of the inverter into a three-phase alternating-current power, performs a commutation of a conduction for each phase of the electric motor sequentially, and thereby, each phase current, which is alternating-current, flows. On the other hand, when the electric motor is in a regenerative mode, the load control unit 21 converts the generated alternating-current power output from the electric motor into a direct-current power, while the load control unit 21 synchronizes based on a rotation angle of the electric motor.

The connection switching control unit 22 can drive the first and second converter circuits 11 and 12 independently from each other by inputting signals (PWM signals) based on pulse width modulation (PWM) into a gate of each switching device provided in the first and second converter circuits 11 and 12 .

As described above, the power device 10 according to the embodiment of the present invention can sequentially perform any voltage control within a desired voltage range from any one of the first voltage VB1 of the first power source BT 1 , the second voltage VB2 of the second power source BT 2 , and the third voltage VB3 of the third power source BT 3 to a voltage which is equal to or more than the summed voltage (VB1+VB2+VB3) of the first voltage VB1 of the first power source BT 1 , the second voltage VB2 of the second power source BT 2 , and the third voltage VB3 of the third power source BT 3 .

Thereby, for example, the power device 10 can be adapted easily to various systems by setting the number of the power sources and the number of the converter circuits which are adapted to the desired voltage range when the power device 10 is designed. Therefore, the controllable voltage range is enlarged, and thereby, the general versatility can be improved.

(First Variation)

In the embodiment described above, as a first variation illustrated in FIG. 2 , the power device 10 may include more than four power sources and more than three converter circuits without being limited to three power sources including the first to third power sources BT 1 to BT 3 and two converter circuits including the first and second converter circuits 11 and 12 .

For example, a power device 10 according to the first variation illustrated in FIG. 2 further includes a fourth power source BT 4 , a third converter circuit (CV 3 ) 30 , a seventh electrical potential point P 7 , and an eighth electrical potential point P 8 compared to the embodiment described above.

The seventh electrical potential point P 7 is connected with a negative electrode of the fourth power source BT 4 , and the eighth electrical potential point P 8 is connected with a positive electrode of the fourth power source BT 4 . The third converter circuit 30 is connected with the fifth electrical potential point P 5 , the sixth electrical potential point P 6 , the seventh electrical potential point P 7 , and the eighth electrical potential point P 8 .

As discussed later, the third converter circuit 30 includes at least step-down or step-up direct-current power converter circuit, and is controlled based on signals output from the control device 15 so that the third converter circuit 30 drives independently.

The third converter circuit 30 controls a voltage, applied between the fifth electrical potential point P 5 and the eighth electrical potential point P 8 , to be within a range from a third voltage VB3 of the third power source BT 3 or a fourth voltage VB4 of the fourth power source BT 4 to a summed voltage (VB3+VB4) of the third voltage VB3 of the third power source BT 3 and the fourth voltage VB4 of the fourth power source BT 4 , and/or controls the voltage, applied between the fifth electrical potential point P 5 and the eighth electrical potential point P 8 , to be equal to or more than the summed voltage (VB3+VB4) of the third voltage VB3 of the third power source BT 3 and the fourth voltage VB4 of the fourth power source BT 4 .

In other words, the power device 10 includes N power sources including first to N-th power sources BT 1 , . . . , BTN, (2*N) electrical potential points including first to (2*N)-th electrical potential points P 1 , . . . , P(2*N), and (N−1) converter circuits including first to (N−1)-th converter circuits CV 1 , . . . , CV(N−1). N is a natural number which is equal to or more than 3, K is an arbitrary natural number which is equal to or less than the natural number N (1≦K≦N), and L is an arbitrary natural number which is equal to or less than (the natural number N−1) (1≦L≦N−1).

As illustrated in FIG. 3A , a negative electrode of the K-th power source is connected with the (2*K−1)-th electrical potential point, and a positive electrode of the K-th power source is connected with the (2*K)-th electrical potential point.

As illustrated in FIG. 3B , the L-th converter circuit CVL is connected with the (2L−1)-th to (2L+2)-th electrical potential points. The L-th converter circuit CVL controls a voltage, applied between the (2L−1)-th electrical potential point and the (2L+2)-th electrical potential point, to be within a range from a voltage of the L-th power source BTL or a voltage of the (L+1)-th power source BT(L+1) to a summed voltage of the voltage of the L-th power source BTL and the voltage of the (L+1)-th power source BT(L+1), and/or controls the voltage, applied between the (2L−1)-th electrical potential point and the (2L+2)-th electrical potential point, to be equal to or more than the summed voltage of the voltage of the L-th power source BTL and the voltage of the (L+1)-th power source BT(L+1).

The power device 10 according to the first variation can sequentially perform any voltage control within a desired voltage range from any one of the voltages of the first to N-th power sources BT 1 , . . . , BTN to a voltage which is equal to or more than the summed voltage of the first to N-th power sources BT 1 , . . . , BTN.

Thereby, for example, the power device 10 can be adapted easily to various systems by setting the number of the power sources and the number of the converter circuits which are adapted to the desired voltage range when the power device 10 is designed. Therefore, the controllable voltage range is enlarged, and thereby, the general versatility can be improved.

(Second Variation)

In the embodiment and the first variation described above, the power device 10 may include, in addition to the load 13 , at least one second load 31 connected with at least one of the converter circuits in parallel.

For example, in a second variation illustrated in FIG. 4 , a second load 31 (LD 1 ) is connected with the first converter circuit 11 in parallel. In this case, a voltage applied to the load 13 is arbitrarily controllable based on the operations of the first and second converter circuits 11 and 12 , and a voltage applied to the load 31 is also arbitrarily controllable.

In more detail, for example, if the first to third voltages VB1 to VB3 are the same (VB1=VB2=VB3=VB), a voltage V123 applied to the load 13 is represented by V123=VB*(RT1+RT2−1), and a voltage V12 applied to the second load 31 is represented by V12=V1*RT1. RT1 is the step-up ratio of the first converter circuit 11 , and RT2 is the step-up ratio of the second converter circuit 12 . Thereby, the voltage V123 applied to the load 13 is controllable so that the step-up ratio of each power source BT 1 to BT 3 to the voltage VB is arbitrarily set within a range from 1 to 3, and the voltage V12 applied to the second load 31 is controllable so that the step-up ratio of each power source BT 1 to BT 3 to the voltage VB is arbitrarily set within a range from 1 to 2.

According to the second variation, for example, in a hybrid vehicle equipped with two electric motors including first and second electric motors, if the load 13 is the first electric motor and the second load 31 is the second electric motor, each of the voltages applied to the first and second electric motors is arbitrarily controllable.

(Third Variation)

In the embodiment and the first and second variations described above, the power device 10 may include, in addition to the load 13 , at least one third load 32 connected with at least one of the power sources in parallel.

For example, in a third variation illustrated in FIG. 5 , in addition to the first load 13 and the second load 31 connected with the first converter circuit 11 in parallel, a third load 32 (LD 2 ) is connected with the first power source BT 1 in parallel. According to the third variation, for example, in a hybrid vehicle which is equipped with the two electric motors including the first and second electric motors and is connectable with an external charger, the load 13 is the first electric motor, the second load 31 is the second electric motor, and the third load 32 is the external charger. By driving the power device 10 so that the step-up ratio of the first and second converter circuits 11 and 12 is equal to 1, charging power can be equally supplied to each power source BT 1 to BT 3 without the need to increase the output voltage of the external charger.

(Fourth Variation)

In the embodiment and the first, second, and third variations described above, the power device 10 may include a fourth load 33 in addition to the load 13 . One end of the fourth load 33 may be connected with a first of a pair among the several electrical potential points, and the other end of the fourth load 33 may be connected with a second of the pair.

For example, in a fourth variation illustrated in FIG. 6 , in addition to the load 13 , the second load 31 (LD 1 , LD 3 ) connected with each first and second converter circuit 11 and 12 in parallel, and the third load 32 (LD 2 ) connected with the first power source BT 1 in parallel, one end of a fourth load 33 (LD 4 ) is connected with the first electrical potential point P 1 and the other end of the fourth load 33 (LD 4 ) is connected with the third electrical potential point P 3 . In this case, the voltage applied to each load 13 , 31 , 32 , and 33 is arbitrarily controllable based on the operations of the first and second converter circuits 11 and 12 .

First Example

Hereinafter, a power device 10 according to a first example of the embodiment described above will be described with reference to the attached drawings.

The power device 10 according to the first example includes first and second converter circuits 11 and 12 as illustrated in FIGS. 7 and 8A . As illustrated in FIGS. 8A and 8B , the first and second converter circuits 11 and 12 are the same, and include first to third switching devices SW 1 to SW 3 such as IGBT (Insulated Gate Bipolar mode Transistor), first and second reactors L 1 and L 2 , and first to sixth nodes A to F.

A capacitor CA 1 is connected between a first electrical potential point P 1 and a fourth electrical potential point P 4 in the first converter circuit 11 , and a capacitor CA 2 is connected between a third electrical potential point P 3 and a sixth electrical potential point P 6 in the second converter circuit 12 . Each capacitor CA 1 and CA 2 may be omitted.

A positive electrode of the second power source BTb (the second power source BT 2 in the first converter circuit 11 , or the third power source BT 3 in the second converter circuit 12 ) is connected with the first node A (A 1 in the first converter circuit 11 , or A 2 in the second converter circuit 12 ), and a negative electrode of the second power source BTb is connected with the second node B (B 1 in the first converter circuit 11 , or B 2 in the second converter circuit 12 ).

A positive electrode of the first power source BTa (the first power source BT 1 in the first converter circuit 11 , or the second power source BT 2 in the second converter circuit 12 ) is connected with the third node C (C 1 in the first converter circuit 11 , or C 2 in the second converter circuit 12 ), and a negative electrode of the first power source BTa is connected with the fourth node D (D 1 in the first converter circuit 11 , or D 2 in the second converter circuit 12 ).

One end of the second reactor L 2 is connected with the fifth node E (E 1 in the first converter circuit 11 , or E 2 in the second converter circuit 12 ) and the other end of the second reactor L 2 is connected with the third node C (C 1 in the first converter circuit 11 , or C 2 in the second converter circuit 12 ).

One end of the first reactor L 1 is connected with the sixth node F (F 1 in the first converter circuit 11 , or F 2 in the second converter circuit 12 ) and the other end of the first reactor L 1 is connected with the second node B (B 1 in the first converter circuit 11 , or B 2 in the second converter circuit 12 ).

A collector and an emitter of the first switching device SW 1 are connected with the fifth node E and the sixth node F, respectively. A collector and an emitter of the second switching device SW 2 are connected with the sixth node F and the fourth node D, respectively. A collector and an emitter of the third switching device SW 3 are connected with the first node A and the fifth node E, respectively. Diodes D 1 to D 3 are connected between the emitter and collector of the switching devices SW 1 to SW 3 , respectively. The direction from the emitter to the collector of each switching device SW 1 to SW 3 is a forward direction of each diode D 1 to D 3 .

A first electrical potential point P 1 is the same as the fourth node D 1 , a second electrical potential point P 2 is the same as the third node C 1 , a third electrical potential point P 3 is the same as the second node B 1 and the fourth node D 2 , a fourth electrical potential point P 4 is the same as the first node A 1 and the third node C 2 , a fifth electrical potential point P 5 is the same as the second node B 2 , and a sixth electrical potential point P 6 is the same as the second node A 2 .

The first and second converter circuits 11 and 12 are controlled based on pulse-width-modulated signals (PWM signals) output from the control device 15 and input into a gate of each switching device SW 1 to SW 3 so that the first and second converter circuits 11 and 12 drive independently from each other.

In more detail, each first and second converter circuit 11 and 12 is controlled so that the first switching device SW 1 and the second and third switching devices SW 2 and SW 3 are switched. In this switching operation, close (ON) and open (OFF) of each switching device SW 1 to SW 3 are switched alternately.

For example, as illustrated in FIGS. 9A and 9B , in a power mode where direct-current power is supplied to the load 13 and in a regenerative mode where direct-current power is supplied from the load 13 , the first switching device SW 1 is turned off and the second and third switching devices SW 2 and SW 3 are turned on. Thereby, the first and second power sources BTa and BTb are connected in parallel between the first node A and the fourth node D. On the other hand, the first and second power sources BTa and BTb are connected in series between the first node A and the fourth node D by having the first switching device SW 1 tuned on and the second and third switching devices SW 2 and SW 3 turned off.

A connection switching control unit 22 included in the control device 15 controls a switching operation of each the first to third switching device SW 1 to SW 3 based on a duty DT. In the switching operation, the first switching device SW 1 and the second and third switching devices SW 2 and SW 3 are inverted and the alternative close and open (ON/OFF) switching operations of each switching device SW 1 to SW 3 are performed for each first and second converter circuit 11 and 12 . The duty is defined by ON time t(SW 1 ) of the first switching device SW 1 and ON time t(SW 2 &SW 3 ) of the second and third switching devices SW 2 and SW 3 . The connection switching control unit 22 arbitrarily controls a voltage V0, applied between the first node A and the fourth node D, to be between the voltage of the first power source BTa or the second power source BTb and the summed voltage of the first and second power sources BTa and BTb by increasing and decreasing the duty DT every the first and second converter circuits 11 and 12 .

Thereby, for example, if the first to third voltages VB1 to VB3 are the same (VB1=VB2=VB3=VB), the step-up ratio of the voltage applied to the load 13 is controlled to be set at an arbitrary value between 1 to 3.

Second Example

Hereinafter, a power device 10 according to a second example of the embodiment described above will be described with reference to the attached drawings.

The power device 10 according to the second example includes first and second converter circuits 11 and 12 as illustrated in FIGS. 10 and 11A . As illustrated in FIGS. 11A and 11B , the first and second converter circuits 11 and 12 are the same, and include first to fourth switching devices SW 1 to SW 4 such as IGBT, first and second reactors L 1 and L 2 , and first to sixth nodes A to F.

A capacitor CA 1 is connected between a first electrical potential point P 1 and a fourth electrical potential point P 4 in the first converter circuit 11 , and a capacitor CA 2 is connected between a third electrical potential point P 3 and a sixth electrical potential point P 6 in the second converter circuit 12 . Each capacitor CA 1 and CA 2 may be omitted.

A positive electrode of a second power source BTb (a second power source BT 2 in the first converter circuit 11 , or a third power source BT 3 in the second converter circuit 12 ) is connected with the first node A (A 1 in the first converter circuit 11 , or A 2 in the second converter circuit 12 ), and a negative electrode of the second power source BTb is connected with the second node B (B 1 in the first converter circuit 11 , or B 2 in the second converter circuit 12 ).

A positive electrode of the first power source BTa (a first power source BT 1 in the first converter circuit 11 , or the second power source BT 2 in the second converter circuit 12 ) is connected with the third node C (C 1 in the first converter circuit 11 , or C 2 in the second converter circuit 12 ), and a negative electrode of the first power source BTa is connected with the fourth node D (D 1 in the first converter circuit 11 , or D 2 in the second converter circuit 12 ).

One end of the second reactor L 2 is connected with the fifth node E (E 1 in the first converter circuit 11 , or E 2 in the second converter circuit 12 ) and the other end of the second reactor L 2 is connected with the third node C (C 1 in the first converter circuit 11 , or C 2 in the second converter circuit 12 ).

One end of the first reactor L 1 is connected with the sixth node F (F 1 in the first converter circuit 11 , or F 2 in the second converter circuit 12 ) and the other end of the first reactor L 1 is connected with the second node B (B 1 in the first converter circuit 11 , or B 2 in the second converter circuit 12 ).

A collector and an emitter of the first switching device SW 1 are connected with the third node C and the sixth node F, respectively. A collector and an emitter of the second switching device SW 2 are connected with the sixth node F and the fourth node D, respectively. A collector and an emitter of the third switching device SW 3 are connected with the first node A and the fifth node E, respectively. A collector and an emitter of the fourth switching device SW 4 are connected with the fifth node E and the second node B, respectively. Diodes D 1 to D 4 are connected between the emitter and collector of the switching devices SW 1 to SW 4 , respectively. The direction from the emitter to the collector of each switching device SW 1 to SW 4 is a forward direction of each diode D 1 to D 4 .

A first electrical potential point P 1 is the same as the fourth node D 1 , a second electrical potential point P 2 is the same as the third node C 1 , a third electrical potential point P 3 is the same as the second node B 1 and the fourth node D 2 , a fourth electrical potential point P 4 is the same as the first node A 1 and the third node C 2 , a fifth electrical potential point P 5 is the same as the second node B 2 , and a sixth electrical potential point P 6 is the same as the first node A 2 .

As illustrated in FIG. 11B , the first converter circuit 11 and the second converter circuit 12 include a first direct-current power converter circuit (REG 1 ) 41 and a second direct-current power converter circuit (REG 2 ) 42 , respectively.

The first direct-current power converter circuit (REG 1 ) 41 includes the first and second switching devices SW 1 and SW 2 , and the first reactor L 1 .

The second direct-current power converter circuit (REG 2 ) 42 includes the third and fourth switching devices SW 3 and SW 4 , and the second reactor L 2 .

The first and second converter circuits 11 and 12 are controlled so that the first and second converter circuits 11 and 12 drive independently from each other based on pulse-width-modulated signals (PWM signals) output from a control device 15 and input into a gate of each switching device SW 1 to SW 4 .

In more detail, each first and second converter circuit 11 and 12 is controlled so that a switching operation for at least one of a pair of the first and second switching devices SW 1 and SW 2 included in the first direct-current power converter circuit 41 and a pair of the third and fourth switching devices SW 3 and SW 4 included in the second direct-current power converter circuit 42 is performed. In this switching operation, close (ON) and open (OFF) of each switching device SW 1 to SW 4 are switched alternately.

For example, as illustrated in FIGS. 12A and 12B , a connection switching control unit 22 included in the control device 15 controls a switching operation of the first switching device SW 1 and the second switching device SW 2 included in the first direct-current power converter circuit 41 based on a first duty DT 1 . In the switching operation, the first switching device SW 1 and the second switching device SW 2 are inverted and the alternative close and open (ON/OFF) switching operations of each switching device SW 1 and SW 2 are performed for each first and second converter circuit 11 and 12 . The first duty DT 1 is defined by ON time t(SW 1 ) of the first switching device SW 1 and ON time t(SW 2 ) of the second switching device SW 2 . The connection switching control unit 22 can step down a first voltage VBa of the first power source BTa based on the first duty DT 1 and output the step-down voltage from the first direct-current power converter circuit 41 . The connection switching control unit 22 controls output voltage V10 of the first direct-current power converter circuit 41 (in other words, the voltage applied between a second node B and a fourth node D) as the product of the first voltage VBa and the first duty DT 1 (VBa*DT 1 =V10).

For example, as illustrated in FIGS. 12A and 12B , the connection switching control unit 22 controls a switching operation of the third switching device SW 3 and the fourth switching device SW 4 included in the second direct-current power converter circuit 42 based on a second duty DT 2 . In the switching operation, the third switching device SW 3 and the fourth switching device SW 4 are inverted and the alternative close and open (ON/OFF) switching operations of each switching device SW 3 and SW 4 are performed for each first and second converter circuit 11 and 12 . The second duty DT 2 is defined by ON time t(SW 3 ) of the third switching device SW 3 and ON time t(SW 4 ) of the fourth switching device SW 4 . The connection switching control unit 22 can step down a second voltage VBb of the second power source BTb based on the second duty DT 2 and output the step-down voltage from the second direct-current power converter circuit 42 . The connection switching control unit 22 controls output voltage V20 of the second direct-current power converter circuit 42 (in other words, the voltage applied between the first node A and the third node C) as the product of the second voltage VBb and the second duty DT 2 (VBb*DT 2 =V20).

Thereby, the connection switching control unit 22 controls arbitrarily the voltage V0, applied between the first node A and the fourth node D, every the first and second converter circuits 11 and 12 so that the voltage V0 is within a range from the first voltage BTa or the second voltage BTb to a summed voltage of the first voltage BTa or the second voltage BTb.

Thereby, for example, if the first to third voltages VB1 to VB3 are the same (VB1=VB2=VB3=VB), the step-up ratio of the voltage applied to the load 13 is controlled to be set at an arbitrary value between 1 to 3.

Third Example

Hereinafter, a power device 10 according to a third example of the embodiment described above will be described with reference to the attached drawings.

The power device 10 according to the third example includes first and second converter circuits 11 and 12 as illustrated in FIG. 13 . The first and second converter circuits 11 and 12 are the same. The first and second converter circuits 11 and 12 include first to sixth nodes A to F, a first direct-current power converter circuit (REG 1 ) 41 and a second direct-current power converter circuit (REG 2 ) 42 . The first direct-current power converter circuit (REG 1 ) 41 includes first and second switching devices SW 1 and SW 2 such as IGBT, and a first reactor L 1 . The second direct-current power converter circuit (REG 2 ) 42 includes the first switching device SW 1 and a third switching device SW 3 such as IGBT, and a second reactor L 2 .

A positive electrode of a second power source BTb (a second power source BT 2 in the first converter circuit 11 , or a third power source BT 3 in the second converter circuit 12 ) is connected with the first node A, a negative electrode of the second power source BTb is connected with the second node B, a positive electrode of a first power source BTa (a first power source BT 1 in the first converter circuit 11 , or a second power source BT 2 in the second converter circuit 12 ) is connected with the third node C, and a negative electrode of the first power source BTa is connected with the fourth node D. One end of the second reactor L 2 is connected with the fifth node E and the other end of the second reactor L 2 is connected with the second node B. One end of the first reactor L 1 is connected with the sixth node F and the other end of the first reactor L 1 is connected with the third node C.

A collector and an emitter of the first switching device SW 1 are connected with the fifth node E and the sixth node F, respectively. A collector and an emitter of the second switching device SW 2 are connected with the sixth node F and the fourth node D, respectively. A collector and an emitter of the third switching device SW 3 are connected with the first node A and the fifth node E, respectively. Diodes D 1 to D 3 are connected between the emitter and collector of the switching devices SW 1 to SW 3 , respectively. The direction from the emitter to the collector of each switching device SW 1 to SW 3 is a forward direction of each diode D 1 to D 3 .

As illustrated in FIGS. 14A and 1413 , a connection switching control unit 22 included in a control device 15 controls a switching operation of the first switching device SW 1 and the second switching device SW 2 included in the first direct-current power converter circuit 41 based on a first duty DT 1 . In the switching operation, the first switching device SW 1 and the second switching device SW 2 are inverted and the alternative close and open (ON/OFF) switching operations of each switching device SW 1 and SW 2 are performed for each first and second converter circuit 11 and 12 . The first duty DT 1 is defined by ON time t(SW 1 ) of the first switching device SW 1 and ON time t(SW 2 ) of the second switching device SW 2 . The connection switching control unit 22 can step up a first voltage VBa of the first power source BTa based on the first duty DT 1 and output the step-up voltage from the first direct-current power converter circuit 41 . The connection switching control unit 22 controls output voltage V10 of the first direct-current power converter circuit 41 (in other words, the voltage applied between a fifth node E and a fourth node D) based on the first voltage VBa and the first duty DT 1 .

As illustrated in FIGS. 14A and 14B , the connection switching control unit 22 controls a switching operation of the first switching device SW 1 and the third switching device SW 3 included in the second direct-current power converter circuit 42 based on a second duty DT 2 . In the switching operation, the first switching device SW 1 and the third switching device SW 3 are inverted and the alternative close and open (ON/OFF) switching operations of each switching device SW 1 and SW 3 are performed for each first and second converter circuit 11 and 12 . The second duty DT 2 is defined by ON time t(SW 1 ) of the first switching device SW 1 and ON time t(SW 3 ) of the third switching device SW 3 . The connection switching control unit 22 can step up a second voltage VBb of the second power source BTb based on the second duty DT 2 and output the step-up voltage from the second direct-current power converter circuit 42 . The connection switching control unit 22 controls output voltage V20 of the second direct-current power converter circuit 42 (in other words, the voltage applied between the first node A and the sixth node F) based on the second voltage VBb and the second duty DT 2 .

Thereby, the connection switching control unit 22 controls arbitrarily voltage V0, applied between the first node A and the fourth node D, every the first and second converter circuits 11 and 12 so that the voltage V0 is equal to or more than the summed voltage of the first voltage VBa and the second voltage VBb.

Thereby, the voltage applied to the load 13 is controlled to be set at an arbitrary value which is equal to or more than the summed voltage of the first to third voltage VB 1 to VB3 (VB1+VB2+VB3).

Fourth Example

Hereinafter, a power device 10 according to a fourth example of the embodiment described above will be described with reference to the attached drawings.

As illustrated in FIG. 15 , each first and second converter circuit 11 and 12 of the power device 10 according to the fourth example includes a switching device SW 1 which is a bidirectional switch, instead of the switching device SW 1 of the third example, and further includes fourth and fifth switching devices SW 4 and SW 5 .

A first direct-current power converter circuit (REG 1 ) 41 includes the first switching device SW 1 , a second switching device SW 2 , the fourth switching device SW 4 , and a first reactor L 1 .

A second direct-current power converter circuit (REG 2 ) 42 includes the first switching device SW 1 , a third switching device SW 3 , the fifth switching device SW 5 , and a second reactor L 2 .

For example, the first switching device SW 1 , which is a bidirectional switch, includes two switching devices SW 1 a and SW 1 b . These two switching devices SW 1 a and SW 1 b are connected in series to have opposite polarities.

A collector and an emitter of the fourth switching device SW 4 are connected with a fifth node E and a fourth node D, respectively. A collector and an emitter of the fifth switching device SW 5 are connected with a first node A and a sixth node F, respectively. A diode D 4 is connected between the emitter and collector of the fourth switching device SW 4 , and a diode D 5 is connected between the emitter and collector of the fifth switching device SW 5 . The direction from the emitter to the collector of each switching device SW 4 and SW 5 is a forward direction of each diode D 4 and D 5 .

As illustrated in FIGS. 16A and 16B , a connection switching control unit 22 included in a control device 15 controls a switching operation of the first switching device SW 1 and the fourth switching device SW 4 included in the first direct-current power converter circuit 41 based on a first step-down duty DT 11 . In the switching operation, the first switching device SW 1 and the fourth switching device SW 4 are inverted and the alternative close and open (ON/OFF) switching operations of each switching device SW 1 and SW 4 are performed for each first and second converter circuit 11 and 12 . The first step-down duty DT 11 is defined by ON time t(SW 1 ) of the first switching device SW 1 and ON time t(SW 4 ) of the fourth switching device SW 4 . The connection switching control unit 22 can step down a first voltage VBa based on the first step-down duty DT 11 and output the step-down voltage from the first direct-current power converter circuit 41 . The connection switching control unit 22 controls output voltage V10a of the first direct-current power converter circuit 41 (in other words, the voltage applied between the fifth node E and the fourth node D) as the product of the first voltage VBa and the first step-down duty DT 11 (VBa*DT 11 =V10a).

As illustrated in FIGS. 16A and 16B , the connection switching control unit 22 controls a switching operation of the first switching device SW 1 and the fifth switching device SW 5 included in the second direct-current power converter circuit 42 based on a second step-down duty DT 21 . In the switching operation, the first switching device SW 1 and the fifth switching device SW 5 are inverted and the alternative close and open (ON/OFF) switching operations of each switching device SW 1 and SW 5 are performed for each first and second converter circuit 11 and 12 . The second step-down duty DT 21 is defined by ON time t(SW 1 ) of the first switching device SW 1 and ON time t(SW 5 ) of the fifth switching device SW 5 . The connection switching control unit 22 can step down a second voltage VBb based on the second step-down duty DT 21 and output the step-down voltage from the second direct-current power converter circuit 42 . The connection switching control unit 22 controls output voltage V20a of the second direct-current power converter circuit 42 (in other words, the voltage applied between the first node A and the sixth node F) as the product of the second voltage VBb and the second step-down duty DT 21 (VBb*DT 21 =V20a).

Thereby, the connection switching control unit 22 controls arbitrarily a voltage V0, applied between the first node A and the fourth node D, to be between the voltage of the first power source BTa or the second power source BTb and the summed voltage of the first and second power sources BTa and BTb, every the first and second converter circuits 11 and 12 .

Thereby, for example, if the first to third voltages VB1 to VB3 are the same (VB1=VB2=VB3=VB), the step-up ratio of the voltage applied to a load 13 is controlled to be set at an arbitrary value between 1 to 3.

As illustrated in FIGS. 16C and 16D , the connection switching control unit 22 included in the control device 15 controls a switching operation of the first switching device SW 1 and the second switching device SW 2 included in the first direct-current power converter circuit 41 based on a first step-up duty DT 12 . In the switching operation, the first switching device SW 1 and the second switching device SW 2 are inverted and the alternative close and open (ON/OFF) switching operations of each switching device SW 1 and SW 2 are performed for each first and second converter circuit 11 and 12 . The first step-up duty DT 12 is defined by ON time t(SW 1 ) of the first switching device SW 1 and ON time t(SW 2 ) of the second switching device SW 2 . The connection switching control unit 22 can step up the first voltage VBa based on the first step-up duty DT 12 and output the step-up voltage from the first direct-current power converter circuit 41 . The connection switching control unit 22 controls output voltage V10b of the first direct-current power converter circuit 41 (in other words, the voltage applied between the fifth node E and the fourth node D) based on the first voltage VBa and the first step-up duty DT 12 .

As illustrated in FIGS. 16C and 16D , the connection switching control unit 22 included in the control device 15 controls a switching operation of the first switching device SW 1 and the third switching device SW 3 included in the second direct-current power converter circuit 42 based on a second step-up duty DT 22 . In the switching operation, the first switching device SW 1 and the third switching device SW 3 are inverted and the alternative close and open (ON/OFF) switching operations of each switching device SW 1 and SW 3 are performed for each first and second converter circuit 11 and 12 . The second step-up duty DT 22 is defined by ON time t(SW 1 ) of the first switching device SW 1 and ON time t(SW 3 ) of the third switching device SW 3 . The connection switching control unit 22 can step up the second voltage VBb based on the second step-up duty DT 22 and output the step-up voltage from the second direct-current power converter circuit 42 . The connection switching control unit 22 controls output voltage V20b of the second direct-current power converter circuit 42 (in other words, the voltage applied between the first node A and the sixth node F) based on the second voltage VBb and the second step-up duty DT 22 .

Thereby, the connection switching control unit 22 controls arbitrarily the voltage V0, applied between the first node A and the fourth node D, every the first and second converter circuits 11 and 12 so that the voltage V0 is equal to or more than the summed voltage of the first voltage VBa and the second voltage VBb.

Thereby, the voltage applied to the load 13 is controlled to be set at an arbitrary value which is equal to or more than the summed voltage of the first to third voltage V131 to VB3 (VB1+VB2+VB3).

Fifth Example

Hereinafter, a power device 10 according to a fifth example of the embodiment described above will be described with reference to the attached drawings.

The power device 10 according to the fifth example includes first and second converter circuits 11 and 12 , which are same each other, as illustrated in FIG. 17 . Each first and second converter circuit 11 and 12 includes first to sixth nodes A to F, a first direct-current power converter circuit (REG 1 ) 41 , and a second direct-current power converter circuit (REG 2 ) 42 . The first direct-current power converter circuit (REG 1 ) 41 includes first and second switching devices SW 1 and SW 2 such as IGBT, and a first reactor L 1 . The second direct-current power converter circuit (REG 2 ) 42 includes third and fourth switching devices SW 3 and SW 4 such as IGBT, and a second reactor L 2 .

A positive electrode of the second power source BTb (a second power source BT 2 in the first converter circuit 11 , or a third power source BT 3 in the second converter circuit 12 ) is connected with the first node A, a negative electrode of the second power source BTb is connected with the second node B, a positive electrode of the first power source BTa (a first power source BT 1 in the first converter circuit 11 , or a second power source BT 2 in the second converter circuit 12 ) is connected with the third node C, and a negative electrode of the first power source BTa is connected with the fourth node D. One end of the second reactor L 2 is connected with the fifth node E and the other end of the second reactor L 2 is connected with the second node B. One end of the first reactor L 1 is connected with the sixth node F and the other end of the first reactor L 1 is connected with the third node C.

A collector and an emitter of the first switching device SW 1 are connected with the second node B and the sixth node F, respectively. A collector and an emitter of the second switching device SW 2 are connected with the sixth node F and the fourth node D, respectively. A collector and an emitter of the third switching device SW 3 are connected with the first node A and the fifth node E, respectively. A collector and an emitter of the fourth switching device SW 4 are connected with the fifth node E and the third node C, respectively. Diodes D 1 to D 4 are connected between the emitter and collector of the switching devices SW 1 to SW 4 , respectively. The direction from the emitter to the collector of each switching device SW 1 to SW 4 is a forward direction of each diode D 1 to D 4 .

As illustrated in FIGS. 18A and 18B , a connection switching control unit 22 included in a control device 15 controls a switching operation of the first switching device SW 1 and the second switching device SW 2 included in the first direct-current power converter circuit 41 based on a first duty DT 1 . In the switching operation, the first switching device SW 1 and the second switching device SW 2 are inverted and the alternative close and open (ON/OFF) switching operations of each switching device SW 1 and SW 2 are performed for each first and second converter circuit 11 and 12 . The first duty DT 1 is defined by ON time t(SW 1 ) of the first switching device SW 1 and ON time t(SW 2 ) of the second switching device SW 2 . The connection switching control unit 22 can step up a first voltage VBa of the first power source BTa based on the first duty DT 1 and output the step-up voltage from the first direct-current power converter circuit 41 . The connection switching control unit 22 controls output voltage V10 of the first direct-current power converter circuit 41 (in other words, the voltage applied between the second node B and the fourth node D) based on the first voltage VBa and the first duty DT 1 .

As illustrated in FIGS. 18A and 18B , the connection switching control unit 22 controls a switching operation of the third switching device SW 3 and the fourth switching device SW 4 included in the second direct-current power converter circuit 42 based on a second duty DT 2 . In the switching operation, the third switching device SW 3 and the fourth switching device SW 4 are inverted and the alternative close and open (ON/OFF) switching operations of each switching device SW 3 and SW 4 are performed for each first and second converter circuit 11 and 12 . The second duty DT 2 is defined by ON time t(SW 3 ) of the third switching device SW 3 and ON time t(SW 4 ) of the fourth switching device SW 4 . The connection switching control unit 22 can step up a second voltage VBb of the second power source BTb based on the second duty DT 2 and output the step-up voltage from the second direct-current power converter circuit 42 . The connection switching control unit 22 controls output voltage V20 of the second direct-current power converter circuit 42 (in other words, the voltage applied between the first node A and the third node C) based on the second voltage VBb and the second duty DT 2 .

Thereby, the connection switching control unit 22 controls arbitrarily voltage V0, applied between the first node A and the fourth node D, every the first and second converter circuits 11 and 12 so that the voltage V0 is equal to or more than the summed voltage of the first voltage VBa and the second voltage VBb.

Thereby, the voltage applied to a load 13 is controlled to be set at an arbitrary value which is equal to or more than the summed voltage of the first to third voltage VB 1 to VB3 (VB1+VB2+VB3).

Sixth Example

Hereinafter, a power device 10 according to a sixth example of the embodiment described above will be described with reference to the attached drawings.

As illustrated in FIGS. 19 and 20 , each first and second converter circuit 11 and 12 of the power device 10 according to the sixth example includes first and fourth switching devices SW 1 and SW 4 , each of which is a bidirectional switch, instead of the switching devices SW 1 and SW 4 of the fifth example, and further includes fifth and sixth switching devices SW 5 and SW 6 .

As illustrated in FIG. 19 , each first and second converter circuit 11 and 12 according to the sixth example includes a first step-down direct-current power converter circuit (REG 11 ) 41 a and a second step-down direct-current power converter circuit (REG 21 ) 42 a . The first step-down direct-current power converter circuit (REG 11 ) 41 a includes a third switching device SW 3 , a fourth switching device SW 4 , a sixth switching device SW 6 , and a second reactor L 2 . The second step-down direct-current power converter circuit (REG 21 ) 42 a includes a first switching device SW 1 , a second switching device SW 2 , a fifth switching device SW 5 , and a first reactor L 1 .

As illustrated in FIG. 20 , each first and second converter circuit 11 and 12 includes a first step-up direct-current power converter circuit (REG 12 ) 41 b and a second step-up direct-current power converter circuit (REG 22 ) 42 b , instead of the first step-down direct-current power converter circuit 41 a and the second step-down direct-current power converter circuit 42 a . The first step-up direct-current power converter circuit (REG 12 ) 41 b includes a first switching device SW 1 , a second switching device SW 2 , a fifth switching device SW 5 , and a first reactor L 1 . The second step-up direct-current power converter circuit (REG 22 ) 42 b includes a third switching device SW 3 , a fourth switching device SW 4 , a sixth switching device SW 6 , and a second reactor L 2 .

For example, the first switching device SW 1 , which is a bidirectional switch, includes two switching devices SW 1 a and SW 1 b . These two switching devices SW 1 a and SW 1 b are connected in series to have opposite polarities. For example, the fourth switching device SW 4 , which is a bidirectional switch, includes two switching devices SW 4 a and SW 4 b . These two switching devices SW 4 a and SW 4 b are connected in series to have opposite polarities.

A collector and an emitter of the fifth switching device SW 5 are connected with a first node A and a sixth node F, respectively. A collector and an emitter of the sixth switching device SW 6 are connected with a fifth node E and a fourth node D, respectively. A fifth diode D 5 is connected between the emitter and collector of the fifth switching device SW 5 , and a sixth diode D 6 is connected between the emitter and collector of the sixth switching device SW 6 . The direction from the emitter to the collector of each switching device SW 5 and SW 6 is a forward direction of each diode D 5 and D 6 .

As illustrated in FIGS. 21A and 2113 , a connection switching control unit 22 included in a control device 15 controls a switching operation of the fourth switching device SW 4 and the sixth switching device SW 6 included in the first step-down direct-current power converter circuit 41 a based on a first step-down duty DT 11 . In the switching operation, the fourth switching device SW 4 and the sixth switching device SW 6 are inverted and the alternative close and open (ON/OFF) switching operations of each switching device SW 4 and SW 6 are performed for each first and second converter circuit 11 and 12 . The first step-down duty DT 11 is defined by ON time t(SW 4 ) of the fourth switching device SW 4 and ON time t(SW 6 ) of the sixth switching device SW 6 . The connection switching control unit 22 can step down a first voltage VB1 based on the first step-down duty DT 11 and output the step-down voltage from the first step-down direct-current power converter circuit 41 a . The connection switching control unit 22 controls output voltage V10a of the first step-down direct-current power converter circuit 41 a (in other words, the voltage applied between the second node B and the fourth node D) as the product of the first voltage VBa and the first step-down duty DT 11 (VBa*DT 11 =V10a).

As illustrated in FIGS. 21A and 21B , the connection switching control unit 22 controls a switching operation of the first switching device SW 1 and the fifth switching device SW 5 included in the second step-down direct-current power converter circuit 42 a based on a second step-down duty DT 21 . In the switching operation, the first switching device SW 1 and the fifth switching device SW 5 are inverted and the alternative close and open (ON/OFF) switching operations of each switching device SW 1 and SW 5 are performed for each first and second converter circuit 11 and 12 . The second step-down duty DT 21 is defined by ON time t(SW 1 ) of the first switching device SW 1 and ON time t(SW 5 ) of the fifth switching device SW 5 . The connection switching control unit 22 can step down a second voltage VBb based on the second step-down duty DT 21 and output the step-down voltage from the second step-down direct-current power converter circuit 42 a . The connection switching control unit 22 controls output voltage V20a of the second step-down direct-current power converter circuit 42 a (in other words, the voltage applied between the first node A and the third node C) as the product of the second voltage VBb and the second step-down duty DT 21 (VBb*DT 21 =V20a).

Thereby, the connection switching control unit 22 controls arbitrarily a voltage V0, applied between the first node A and the fourth node D, to be between the voltage of the first power source BTa or the second power source BTb and the summed voltage of the first and second power sources BTa and BTb, every the first and second converter circuits 11 and 12 .

Thereby, for example, if the first to third voltages VB 1 to VB3 are the same (VB1=VB2=VB3=VB), the step-up ratio of the voltage applied to a load 13 is controlled to be set at an arbitrary value between 1 to 3.

As illustrated in FIGS. 21C and 21D , the connection switching control unit 22 included in the control device 15 controls a switching operation of the first switching device SW 1 and the second switching device SW 2 included in the first step-up direct-current power converter circuit 41 b based on a first step-up duty DT 12 . In the switching operation, the first switching device SW 1 and the second switching device SW 2 are inverted and the alternative close and open (ON/OFF) switching operations of each switching device SW 1 and SW 2 are performed for each first and second converter circuit 11 and 12 . The first step-up duty DT 12 is defined by ON time t(SW 1 ) of the first switching device SW 1 and ON time t(SW 2 ) of the second switching device SW 2 . The connection switching control unit 22 can step up the first voltage VBa based on the first step-up duty DT 12 and output the step-up voltage from the first step-up direct-current power converter circuit 41 b . The connection switching control unit 22 controls output voltage V10b of the first step-up direct-current power converter circuit 41 b (in other words, the voltage applied between the second node B and the fourth node D) based on the first voltage VBa and the first step-up duty DT 12 .

As illustrated in FIGS. 21C and 21D , the connection switching control unit 22 controls a switching operation of the third device SW 3 and the fourth switching device SW 4 included in the second step-up direct-current power converter circuit 42 b based on a second step-up duty DT 22 . In the switching operation, the third switching device SW 3 and the fourth switching device SW 4 are inverted and the alternative close and open (ON/OFF) switching operations of each switching device SW 3 and SW 4 are performed for each first and second converter circuit 11 and 12 . The second step-up duty DT 22 is defined by ON time t(SW 3 ) of the third switching device SW 3 and ON time t(SW 4 ) of the fourth switching device SW 4 . The connection switching control unit 22 can step up a second voltage VBb based on the second step-up duty DT 22 and output the step-up voltage from the second step-up direct-current power converter circuit 42 b . The connection switching control unit 22 controls output voltage V20b of the second step-up direct-current power converter circuit 42 b (in other words, the voltage applied between the first node A and the third node C) based on the second voltage VBb and the second step-up duty DT 22 .

Thereby, the connection switching control unit 22 controls arbitrarily the voltage V0, applied between the first node A and the fourth node D, every the first and second converter circuits 11 and 12 so that the voltage V0 is equal to or more than the summed voltage of the first voltage VBa and the second voltage VBb.

Thereby, the voltage applied to the load 13 is controlled to be set at an arbitrary value which is equal to or more than the summed voltage of the first to third voltage VB1 to VB3 (VB1+VB2+VB3).

Seventh Example

Hereinafter, a power device 10 according to a seventh example of the embodiment described above will be described with reference to the attached drawings.

As illustrated in FIG. 22 , each first and second converter circuit 11 and 12 of the power device 10 according to the seventh example further includes seventh and eighth nodes G and H, and fifth to eighth switching devices SW 5 to SW 8 compared to the fifth example described above.

Each first and second converter circuit 11 and 12 according to the seventh example includes a first direct-current power converter circuit (REG 1 ) 41 and a second direct-current power converter circuit (REG 2 ) 42 . The first direct-current power converter circuit (REG 1 ) 41 includes a first switching device SW 1 , a second switching device SW 2 , a fifth switching device SW 5 , and a sixth switching device SW 6 , and a first reactor L 1 . The second direct-current power converter circuit (REG 2 ) 42 includes a third switching device SW 3 , a fourth switching device SW 4 , a seventh switching device SW 7 , and an eighth switching device SW 8 , and a second reactor L 2 .

The seventh node G is provided between a second node B and the second reactor L 2 . The eighth node H is provided between a third node C and the first reactor L 1 .

A collector and an emitter of the fifth switching device SW 5 are connected with the third node C and the eighth node H, respectively. A collector and an emitter of the sixth switching device SW 6 are connected with the eighth node H and a fourth node D, respectively. A collector and an emitter of the seventh switching device SW 7 are connected with a first node A and the seventh node G, respectively. A collector and an emitter of the eighth switching device SW 8 are connected with the seventh node G and the second node B, respectively. Fifth to eighth diodes D 5 to D 8 are connected between the emitter and collector of the switching devices SW 5 to SW 8 , respectively. The direction from the emitter to the collector of each switching device SW 5 to SW 8 is a forward direction of each diode D 5 to D 8 .

As illustrated in FIGS. 23A and 23B , a connection switching control unit 22 included in a control device 15 controls a switching operation of the fifth switching device SW 5 and the sixth switching device SW 6 included in the first direct-current power converter circuit 41 based on a first step-down duty DT 11 . In the switching operation, the fifth switching device SW 5 and the sixth switching device SW 6 are inverted and the alternative close and open (ON/OFF) switching operations of each switching device SW 5 and SW 6 are performed for each first and second converter circuit 11 and 12 . The first step-down duty DT 11 is defined by ON time t(SW 5 ) of the fifth switching device SW 5 and ON time t(SW 6 ) of the sixth switching device SW 6 . The connection switching control unit 22 can step down a first voltage VBa based on the first step-down duty DT 11 and output the step-down voltage from the first direct-current power converter circuit 41 . The connection switching control unit 22 controls output voltage V10a of the first direct-current power converter circuit 41 (in other words, the voltage applied between the second node B and the fourth node D) as the product of the first voltage VBa and the first step-down duty DT 11 (VBa*DT 11 =V10a).

As illustrated in FIGS. 23A and 23B , the connection switching control unit 22 controls a switching operation of the seventh switching device SW 7 and the eighth switching device SW 8 included in the second direct-current power converter circuit 42 based on a second step-down duty DT 21 . In the switching operation, the seventh switching device SW 7 and the eighth switching device SW 8 are inverted and the alternative close and open (ON/OFF) switching operations of each switching device SW 7 and SW 8 are performed for each first and second converter circuit 11 and 12 . The second step-down duty DT 21 is defined by ON time t(SW 8 ) of the eighth switching device SW 8 and ON time t(SW 7 ) of the seventh switching device SW 7 . The connection switching control unit 22 can step down a second voltage VBb based on the second step-down duty DT 21 and output the step-down voltage from the second direct-current power converter circuit 42 . The connection switching control unit 22 controls output voltage V20a of the second direct-current power converter circuit 42 (in other words, the voltage applied between the first node A and the third node C) as the product of the second voltage VBb and the second step-down duty DT 21 (VBb*DT 21 =V20a).

Thereby, the connection switching control unit 22 controls arbitrarily voltage V0, applied between the first node A and the fourth node D, every the first and second converter circuits 11 and 12 so that the voltage V0 is between the voltage of the first power source BTa or the second power source BTb and the summed voltage of the first and second power sources BTa and BTb.

Thereby, for example, if the first to third voltages VB1 to VB3 are the same (VB1=VB2=VB3=VB), the step-up ratio of the voltage applied to a load 13 is controlled to be set at an arbitrary value between 1 to 3.

As illustrated in FIGS. 23C and 23D , the connection switching control unit 22 included in the control device 15 controls a switching operation of the first switching device SW 1 and the second switching device SW 2 included in the first direct-current power converter circuit 41 based on a first step-up duty DT 12 . In the switching operation, the first switching device SW 1 and the second switching device SW 2 are inverted and the alternative close and open (ON/OFF) switching operations of each switching device SW 1 and SW 2 are performed for each first and second converter circuit 11 and 12 . The first step-up duty DT 12 is defined by ON time t(SW 1 ) of the first switching device SW 1 and ON time t(SW 2 ) of the second switching device SW 2 . The connection switching control unit 22 can step up the first voltage VBa based on the first step-up duty DT 12 and output the step-up voltage from the first direct-current power converter circuit 41 . The connection switching control unit 22 controls output voltage V10b of the first direct-current power converter circuit 41 (in other words, the voltage applied between the second node B and the fourth node D) based on the first voltage VBa and the first step-up duty DT 12 .

As illustrated in FIGS. 23C and 23D , the connection switching control unit 22 controls a switching operation of the third device SW 3 and the fourth switching device SW 4 included in the second direct-current power converter circuit 42 based on a second step-up duty DT 22 . In the switching operation, the third switching device SW 3 and the fourth switching device SW 4 are inverted and the alternative close and open (ON/OFF) switching operations of each switching device SW 3 and SW 4 are performed for each first and second converter circuit 11 and 12 . The second step-up duty DT 22 is defined by ON time t(SW 3 ) of the third switching device SW 3 and ON time t(SW 4 ) of the fourth switching device SW 4 . The connection switching control unit 22 can step up a second voltage VBb based on the second step-up duty DT 22 and output the step-up voltage from the second direct-current power converter circuit 42 . The connection switching control unit 22 controls output voltage V20b of the second direct-current power converter circuit 42 (in other words, the voltage applied between the first node A and the third node C) based on the second voltage VBb and the second step-up duty DT 22 .

Thereby, the connection switching control unit 22 controls arbitrarily the voltage V0, applied between the first node A and the fourth node D, every the first and second converter circuits 11 and 12 so that the voltage V0 is equal to or more than the summed voltage of the first voltage VBa and the second voltage VBb.

Thereby, the voltage applied to the load 13 is controlled to be set at an arbitrary value which is equal to or more than the summed voltage of the first to third voltage VB 1 to VB3 (VB1+VB2+VB3).

The technical scope of the present invention is not limited to the embodiments described above, and includes variations where a variety of modifications are made in the embodiments described above without departing from the spirit or scope of the present invention. In other words, the embodiments described above are illustrative only, and modifications may be made accordingly in the embodiments.

For example, the power source ST is not limited to a dischargeable and chargeable battery. The power source BT may be a fuel cell or a power generator which is only capable of discharging power.