Power storage apparatus, connection apparatus, power storage system, electronic device, motor-driven vehicle, and electric power system

The present application claims priority to Japanese Priority Patent Application JP 2010-274381 filed in the Japan Patent Office on Dec. 9, 2010, the entire content of which is hereby incorporated by reference.

The present application relates to a power storage apparatus having a plurality of power storage elements housed in a case, to a connection apparatus that can be applied to the power storage apparatus, and to a power storage system, a motor-driven vehicle, an electronic device, and an electric power system that use electric power from the power storage apparatus.

In recent years, secondary batteries, such as lithium-ion batteries, have found a wide range of applications in power storage apparatuses for storing electric power, automobile batteries, and the like, in combination with new energy systems, such as solar batteries and wind power generation. In order to generate large output, in a case where many power storage elements, for example, unit batteries (also called cells, in the following description, simply referred to as batteries as appropriate) are used, a configuration in which a plurality of power storage modules are connected in series with one another is adopted. A power storage module is formed such that a plurality of (for example, eight) batteries are connected in parallel and/or in series with one another, thereby constituting a battery block. Many battery blocks are housed in an exterior case, and thus, a power storage module (also called an assembled battery) is formed.

As an example, the output voltage of the single body of the power storage apparatus is set at several tens of Volts. A plurality of such power storage apparatuses are connected in series with one another, so that an output voltage of several hundreds of Volts is obtained. In particular, in a case where a high voltage is generated as described above, it is necessary that consideration is given to the prevention of electric shock. A configuration is described in, for example, PTL 1 below, in which, to prevent electric shock when a battery for an automobile is to be replaced, an isolating switch is turned off when a positioning pin is fitted into a hole when a spent battery is to be replaced. When the isolating switch is turned off, supply of electricity to the connection terminal of a connector is shut off, and thereby safety is ensured.

The disclosure disclosed in PTL 1 above uses the movement of an actuator that moves up and down when the battery is to be replaced. However, there is a problem in that the disclosure disclosed in PTL 1 does not apply to a power storage apparatus that does not have such an up/down mechanism. In addition, in a case where a plurality of power storage apparatuses are to be connected and used, a common controller is provided with respect to a plurality of power storage apparatuses. Communication is performed between a battery monitoring unit and a common controller, so that the charging operation, the discharging operation, and the like of each power storage apparatus are controlled by the controller.

An address for identification is assigned to each power storage apparatus for the purpose of a process in which a controller receives information, such as a voltage, from a plurality of power storage apparatuses and controls each power storage apparatus. The configuration of the power storage apparatus is made the same, and a unique address is set to each power storage apparatus by a user. If electronic parts for which setting of an address is performed are provided inside a case, it becomes necessary to open the lid of the case for the purpose of a setting operation of electronic parts, resulting in decreased work efficiency and electric shock. The same problem occurs also in a case where electronic parts are set through an opening provided in the case without opening the lid thereof. Therefore, exposing electronic parts outside the case is desirable from the viewpoint of work efficiency. However, with the configuration, also, if a voltage output terminal nearby is touched, there is a risk of electric shock, which is problematical in terms of safety.

Accordingly, an object of the present application is to provide a power storage apparatus that enables access to electronic parts from outside a case and further reliably enables the prevention of the risk of electric shock when a setting operation is performed for electronic parts, a connection apparatus that can be applied to the power storage apparatus, and a power storage system, an electronic device, a motor-driven vehicle, and an electric power system that use electric power from the power storage apparatus.

In order to solve the above-mentioned problems, a power storage apparatus of the present application is a power storage apparatus having a battery unit housed in a case, the power storage apparatus including: external terminals of positive and negative poles for providing, from outside the case, electrical connection to corresponding positive and negative poles of the battery unit; and electronic parts, wherein only when a connection with the battery unit is cut from at least one of the external terminals of both the poles, the electronic part can be accessed.

According to an embodiment, there is provided a power storage apparatus having a battery unit and electronic parts housed in a same case the power storage apparatus including: external terminals of positive and negative poles for providing, from outside the case, electrical connection to corresponding positive and negative poles of the battery unit; and a connection unit configured to switch a connected state between at least one of the external terminals of both the poles and the battery unit, wherein the connection unit enables the electronic parts to be accessed only when the connected state is a disconnected state.

According to another embodiment, there is provided a connection apparatus including first and second conductors that are inserted into a power-supply line; a connection unit by which a state in which the first and second conductors contact with each other and a state in which at least one of the first and second conductors is separated from the other; and a cover that is formed integrally with a support part that supports the connection unit and that blocks access to the electronic parts in the vicinity of the first and second conductors.

According to at least one embodiment, a cover that is integral with a connection unit is designed to block access to electronic parts. To access electronic parts, the connection unit is pulled out so that the cover is removed. When the connection unit is pulled out, the connection between first and second conductors is cut, and a voltage is not output to an external terminal. Therefore, it is possible to prevent a risk of receiving an electrical shock from an external terminal.

Additional features and advantages are described herein, and will be apparent from the following Detailed Description and the figures.

FIG. 1 is a block diagram illustrating the overview of a power storage module.

FIG. 2 is a block diagram illustrating the electrical configuration of the power storage module.

FIG. 3 is a perspective view illustrating a state in which a bus bar has been removed.

FIG. 4 is a perspective view illustrating a state in which a bus bar has been mounted.

FIG. 5 is a back view of the power storage module.

FIG. 6 is a plan view of a power storage module in which a portion of a case has been cut out.

FIGS. 7A and 7B are perspective views of a bus bar.

FIG. 8 is a perspective view illustrating a state in which a bus bar has been mounted in a connector.

FIG. 9 is a block diagram illustrating an application example of a power storage system.

FIG. 10 is a block diagram illustrating an application example of a power storage system.

The present application will be described below with reference to the drawings according to the embodiment.

“Overview of Power Storage Module”

In a case where many power storage elements, for example, secondary battery cells (hereinafter referred to as batteries) are to be used to generate large output, a configuration is adopted in which a plurality of power storage apparatuses (hereinafter referred to as power storage modules) are connected, and a control device is provided in common with respect to the plurality of power storage modules. Such a configuration will be referred to as a battery system. The power storage module is a unit in which a plurality of battery cells and a controller are combined.

As shown in FIG. 1 , a power storage module 1 has housed therein batteries BT 1 to BTN that are connected in series with one another in a case. The terminals on the positive pole side of the batteries BT 1 to BTN are connected to a connector 3 a serving as a first conductor through a fuse. Another connector 3 b is provided in the vicinity of the connector 3 a . The connector 3 b is connected to an external terminal 4 on the positive pole side. The terminals on the negative pole side of the batteries BT 1 to BTN are connected to an external terminal 5 on the negative pole side. Inside the case, a metal plate for connection, for example, a bus bar, is used to make series connection between batteries or between battery blocks including a plurality of batteries. A bus bar is a metal in the shape of a long bar.

A detachable bus bar 11 is provided as a connection unit with respect to the connectors 3 a and 3 b . The bus bar 11 has a configuration in which a conduction plate is bent so as to have a pair of plate-shaped projections 12 a and 12 b and the base part of the conduction plate is mounted on one surface of a support plate 13 . A cover 14 is formed as a result of one end of the support plate 13 being extended. Furthermore, a knob 15 is formed on the other surface of the support plate 13 . The support plate 13 having the cover 14 and the knob 15 is, for example, a molded product of synthetic resin.

For example, the connector 3 a and the 3 b have a gap (slit) in which their spring contact plates are made to face each other. As a result of the plate-shaped projections 12 a and 12 b of the bus bar 11 being inserted in the gap of the connectors, the connector 3 a and the connector 3 b are connected (conduct) through the bus bar 11 . On the other hand, as a result of the plate-shaped projections 12 a and 12 b of the bus bar 11 being pulled out from the gap of the connectors, the connector 3 a and the connector 3 b are disconnected (non-conduct). As described above, it is possible to switch between a connected state in which the bus bar 11 has been inserted into the connectors 3 a and 3 b and a non-connected state in which the bus bar 11 has been pulled out from the connectors 3 a and 3 b.

In FIG. 1 , though the illustration is omitted, electronic parts for which, for example, setting of an address of a power storage module is performed, are arranged in the vicinity of the connectors 3 a and 3 b . In the connected state in which the bus bar 11 has been inserted into the connectors 3 a and 3 b , the cover 14 blocks the window on the front side of the operation surface of the electronic parts. That is, in the connected state, access to the electronic parts is blocked. On the other hand, when the bus bar 11 is pulled out from the connectors 3 a and 3 b , the window on the front side of the operation surface of the setting unit opens, making it possible to set, for example, the address of the power storage module by operating the operation surface through the window.

Only when the bus bar 11 is removed and the window on the front side of the operation surface is opened, access to the operation surface becomes possible, and a setting operation of electronic parts becomes possible. By performing a setting operation from outside the case, work efficiency can be improved when compared to operating electronic parts inside the case, and also safety can be increased. In particular, in a case where a plurality of power storage modules are connected in series with one another, the electrical potential of the internal circuit of the high-order power storage module becomes higher than the electrical potential of the internal circuit of the low-order power storage module as a whole. As a result of not providing electronic parts in the inside, safety can be improved. In addition, since a high voltage is not output to the external terminal 4 , the risk of electric shock due to contact with the external terminal 4 at the time of a setting operation can be eliminated.

“Example of Power Storage Module”

FIG. 2 illustrates an example of the electrical configuration of the power storage module 1 . FIGS. 3 and 4 are perspective views illustrating the exterior of the power storage module 1 . The exterior case of the power storage module 1 is constituted by a metal-made lower exterior case 22 a and a metal-made upper exterior case 22 b , which have been subjected to plate sheet processing. The lower exterior case 22 a of the case has a box-shaped configuration, and the upper exterior case 22 b is provided so as to cover the opening thereof. For the material of the lower exterior case 22 a and the upper exterior case 22 b , it is preferable that a material having high thermal conductivity and emissivity be used. It is possible to obtain an excellent housing heat dissipation effect, and thus, it is possible to suppress a temperature increase in the case. Since an excellent housing heat dissipation effect is provided, it is possible to minimize or discard the opening part of the case, and thus, a high degree of dust/splash proofing can be realized. For example, the material of the lower exterior case 22 a and the upper exterior case 22 b is aluminum, an aluminum alloy, copper, or a copper alloy.

Inside the case, as shown in FIG. 2 , battery blocks B 1 to B 16 , in each of which 8 batteries are connected in parallel with one another, are connected in series with one another, are housed. One battery block is such that, for example, 8 cylindrical lithium ion secondary batteries are connected in parallel with one another. For example, 16 battery blocks B 1 to B 16 are each connected to a control block, and charging/discharging is controlled. Charging/discharging is performed through the external positive pole terminal 4 and the external negative pole terminal 5 . A voltage of 16× Vbat is output from one power storage module. Vbat is a voltage of one battery block.

A rear surface plate 21 of the case is provided with the external positive pole terminal 4 and the external negative pole terminal 5 for charging/discharging with respect to the power storage module 1 . On both sides of the external positive pole terminal 4 , short-circuit prevention walls for preventing short-circuit between terminals are provided. On both sides of the external negative pole terminal 5 , short-circuit prevention walls for preventing short-circuit between terminals are provided.

In addition, on the rear surface plate 21 of the power storage module 1 , windows 25 and 26 are formed in such a manner as to be in proximity with each other. In addition, the rear surface plate 21 is provided with a connector 27 for communication with the controller. Inside the power storage module 1 , a control block for performing monitoring of the voltage, the electrical current, and the temperature of the batteries are provided. Information from the control block is transmitted to an external controller through communication. The controller performs charging management, electrical discharge management, management for deterioration suppression, and the like.

For the communication between the control block of the power storage module 1 and the controller, which is performed through a communication connector 27 , for example, a serial interface is used. For the serial interface, specifically, a system management (SM) bus or the like is used. For example, an I2C bus can be used. An I2C bus is for synchronous serial communication in which communication is performed using a serial clock (SCL) and two signal lines of bi-directional SDA (serial data).

The connectors 3 a and 3 b are vertically provided inside a window 26 formed on the rear surface plate 21 . The connectors 3 a and 3 b have two spring contact plates that are arranged opposed with each other, so that plate-shaped projections 12 a and 12 b of the bus bar 11 are inserted through the window 26 into the opposing gap of the two spring contact plates. In addition, the window 26 is blocked by the cover 14 integral with the support plate 13 of the bus bar 11 . Since both the plate-shaped projections 12 a and 12 b are grasped by the two spring contact plates of the connectors 3 a and 3 b , it is possible to maintain the state in which the bus bar 11 is inserted with respect to the connectors 3 a and 3 b.

Electronic parts to be set or connected are arranged inside the window 26 formed on the rear surface plate 21 . As shown in FIG. 5 , electronic parts include, for example, a slide switch 28 , a rotary switch 29 , and a JTAG connector 30 . An address for the power storage module 1 is set using the rotary switch 29 . It is made possible that a plurality of power storage modules 1 are connected and used. In a case where a plurality of the power storage modules 1 are connected, an address for identification is set to each power storage module. An external controller performs a control process on the basis of the address. The slide switch 28 is used to increase the number of addresses that are specified using the rotary switch 29 .

The JTAG connector 30 is a standard connector, which has been proposed by JTAG (Joint European Test Action). For the purpose of inspection of a microprocessing unit (MPU), an integrated circuit (IC), and the like of the control block inside the case through the JTAG connector 30 , test data is input and output, and also rewriting of the firmware of the internal MPU is performed. For the electronic parts, switching parts, connectors, and the like other than the above-mentioned elements may be used.

FIG. 6 includes a top plan view of the bus bar 11 and a top plan view in which part of the upper exterior case 22 b is cut out. As shown in FIG. 7 , the plate-shaped projections 12 a and 12 b of the bus bar 11 are surrounded by a bus bar cover 16 whose periphery is in the shape of a box. Holes 17 a and 17 b for screwing are provided at corresponding end portions of the support plate 13 and the cover 14 of the bus bar 11 .

A fuse 2 is mounted in the base part 31 that is fixed to the lower exterior case 22 a . A bus bar (not shown) inside the case is connected at both ends of the fuse. The connector 3 a is provided inside a connector cover 32 a , and the connector 3 b is provided inside a connector cover 32 b.

When the bus bar cover 16 of the bus bar 11 is inserted into the case through the window 26 , the connector covers 32 a and 32 b are inserted into the bus bar cover 16 , the plate-shaped projections 12 a and 12 b are inserted into the slit of the connectors 3 a and 3 b , and the connectors 3 a and 3 b are placed in a connected state through the bus bar 11 . When the bus bar 11 is pulled out by grasping the knob 15 , the connectors 3 a and 3 b enter a non-connected state. In the non-connected state, the window 26 is opened, and access to the internal electronic parts (the slide switch 28 , the rotary switch 29 , and the JTAG connector 30 ) for which setting is performed becomes possible through the window 26 . Then, processing, such as setting of addresses, testing of internal ICs, and rewriting of the firmware of the internal MPU, is performed.

According to the above-mentioned present disclosure, by performing the setting operation of electronic parts from outside the case, work efficiency can be improved when compared to operating electronic parts inside the case, and also safety can be increased. In particular, in a case where a plurality of power storage modules are connected in series with one another, the electrical potential of the internal circuit of the power storage module on a higher side increases. In addition, only in a case where the bus bar 11 is removed and the window on the front side of the operation surface is opened, access to the electronic parts becomes possible. In this case, since a high voltage is not output to the external terminal 4 , the risk of electric shock due to contacting the external terminal 4 at the time of a setting operation can be eliminated.

In the above-mentioned description, a lithium ion secondary battery is used as a power storage element. However, a secondary battery other than a lithium ion secondary battery may be used. In addition, a power storage element other than a secondary battery, for example, an electric double layer capacitor, may be used. Furthermore, access to the setting unit is blocked by blocking the window by using the cover of the bus bar 11 . Alternatively, a configuration is also possible in which the bus bar 11 has a shape by which permission/nonpermission of lid opening/closing can be specified and a lid that covers the setting unit does not open unless the bus bar 11 is removed.

The present application is a power storage system that is charged by a power generation apparatus in which the above-mentioned power storage apparatus performs power generation from renewable energy.

The present application is a power storage system that has the above-mentioned power storage apparatus and that supplies electric power to an electronic device that is connected to the power storage apparatus.

The present application is an electronic device that receives the supply of electric power from the above-mentioned power storage apparatus.

The electronic device and the electric power system are implemented as, for example, an electric power supply system for housing. In addition, the electronic device and the electric power system are implemented as a system that provides, in cooperation with an external electric power supply network, efficient supply of electric power.

In addition, the present application is a motor-driven vehicle including a conversion device that receives supply of electric power from the above-mentioned power storage apparatus and converts the electric power into a driving force for the vehicle, and a control device that performs information processing for vehicle control on the basis of the information on the power storage apparatus.

The present application is an electric power system that includes an electric power information transmitting/receiving unit configured to transmit and receive a signal to and from another apparatus through a network and that performs charging/discharging control of the above-mentioned power storage apparatus on the basis of the information received by the transmitting/receiving unit.

The present application is an electric power system that receives supply of electric power from the above-mentioned power storage apparatus or supplies electric power to the power storage apparatus from a power generation apparatus or an electric power network.

“Power Storage System in Housing as Application Example”

A description will be given, with reference to FIG. 9 , of an example in which the present application is applied to a power storage system for housing. For example, in a power storage system 100 for a housing 101 , electric power is supplied from a centralized power system 102 , such as thermal power generation 102 a , atomic power generation 102 b , and wind power generation 102 c , to a power storage apparatus 103 through an electric power network 109 , an information network 112 , a smart meter 107 , a power hub 108 , and the like. Along with this, electric power is supplied to the power storage apparatus 103 from an independent power supply, such as an in-house power generation device 104 . The electric power supplied to the power storage apparatus 103 is stored. By using the power storage apparatus 103 , electric power used in the housing 101 is supplied. Not limited to the housing 101 , the same power storage system can be used with regard to a building.

The housing 101 is provided with the power generation device 104 , a power consumption apparatus 105 , a power storage apparatus 103 , a control device 110 that controls each device, a smart meter 107 , and sensors 111 that obtain various information. The devices are connected to one another through the electric power network 109 and the information network 112 . For the power generation device 104 , a solar battery, a fuel battery, or the like is used, and the generated electric power is supplied to the power consumption apparatus 105 and/or the power storage apparatus 103 . Examples of the power consumption apparatus 105 include a refrigerator 105 a , an air-conditioning device 105 b , a television receiver 105 c , and a bath 105 d . In addition, the power consumption apparatus 105 includes a motor-driven vehicle 106 . Examples of the motor-driven vehicle 106 include an electric automobile 106 a , a hybrid car 106 b , and an electric bicycle 106 c.

The above-mentioned power storage apparatus of the present application is applied to the power storage apparatus 103 . The power storage apparatus 103 is constituted by a secondary battery or a capacitor. The power storage apparatus 103 is, for example, constituted by a lithium-ion battery. The lithium-ion battery may be of a stationary type or may be that used in the motor-driven vehicle 106 . The smart meter 107 has functions of measuring the used amount of commercial electric power and transmitting the measured used amount to an electric power company. The electric power network 109 may be any one of DC power feeding, AC power feeding, and noncontact supply of electricity, or may be such that two or more of them are combined.

Examples of various sensors 111 include a human detection sensor, an illumination sensor, an object detection sensor, a power consumption sensor, a vibration sensor, a contact sensor, a temperature sensor, and an infrared sensor. The information obtained by the various sensors 111 is transmitted to the control device 110 . The state of the weather conditions, the state of a person, and the like are understood on the basis of the information from the sensors 111 , and the power consumption apparatus 105 can be automatically controlled to minimize energy consumption. In addition, it is possible for the control device 110 to transmit information on the housing 101 to an external electric power company and the like through the Internet.

Processing, such as branching of electric power lines and DC/AC conversion, is performed by using a power hub 108 . Examples of a communication scheme for an information network 112 that is connected with the control device 110 include a method of using a communication interface, such as UART (Universal Asynchronous Receiver-Transceiver: transmission and reception circuit for asynchronous serial communication), and a method of using a sensor network based on a wireless communication standard, such as Bluetooth, ZigBee, or WiFi. The Bluetooth method can be applied to multimedia communication, so that one-to-many connection communication can be performed. ZigBee uses the physical layer of IEEE (Institute of Electrical and Electronics Engineers) 802.16.4. IEEE 802.16.4 is the title of the short-distance wireless network standard called personal area network (PAN) or wireless (W) PAN.

The control device 110 is connected to an external server 113 . The server 113 may be managed by one of the housing 101 , an electric power company, and a service provider. The information that is transmitted and received by the server 113 is, for example, information on power consumption information, life pattern information, an electric power fee, weather information, natural disaster information, and electricity transaction. These pieces of information may be transmitted and received from an power consumption apparatus (for example, television receiver) inside a household. Alternatively, the pieces of information may be transmitted and received from an out-of-home device (for example, a mobile phone, etc.). These pieces of information may be displayed on a device having a display function, for example, a television receiver, a mobile phone, or a personal digital assistant (PDA).

The control device 110 that controls each unit is constituted by a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), and the like. In this example, the control device 110 is stored in the power storage apparatus 103 . The control device 110 is connected to the power storage apparatus 103 , the in-house power generation device 104 , the power consumption apparatus 105 , the various sensors 111 , and the server 113 through the information network 112 , and has functions of adjusting the use amount of the commercial electric power, and the amount of power generation. In addition, the control device 110 may have a function of performing electricity transaction in the electric power market.

As described above, not only the centralized power system 102 in which power is thermal power 102 a , atomic power 102 b , wind power 102 c , or the like, but also the generated power of the in-house power generation device 104 (solar power generation, wind power generation) can be stored in the power storage apparatus 103 . Therefore, even if the generated power of the in-house power generation device 104 varies, it is possible to perform control such that the amount of electric power to be sent to the outside is made constant or electric discharge is performed by only a necessary amount. For example, usage is possible in which electric power obtained by the solar power generation is stored in the power storage apparatus 103 , late night power whose fee is low during nighttime is stored in the power storage apparatus 103 , and the electric power stored by the power storage apparatus 103 is discharged and used in a time zone in which the fee during daytime is high.

In this example, an example has been described in which the control device 110 is stored in the power storage apparatus 103 . Alternatively, the control device 110 may be stored in the smart meter 107 or may be configured singly. In addition, the power storage system 100 may be used by targeting a plurality of households in a block of apartments or may be used by targeting a plurality of single-family detached houses.

“Power Storage System in Vehicle as Application Example”

A description will be given, with reference to FIG. 10 , of an example in which the present application is applied to a power storage system for vehicle. FIG. 10 schematically shows an example of the configuration of a hybrid vehicle adopting a series hybrid power system to which the present application is applied. A series hybrid power system is a car that runs using an electric power driving force transducer by using electric power generated by a power generator that is driven by an engine or by using electric power that is temporarily stored in a battery.

A hybrid vehicle 200 is mounted with an engine 201 , a power generator 202 , an electric power driving force transducer 203 , a driving wheel 204 a , a driving wheel 204 b , a wheel 206 a , a wheel 206 b , a battery 208 , a vehicle control device 209 , various sensors 210 , and a charging slot 211 . The above-mentioned power storage apparatus of the present application is applied to the battery 208 .

The hybrid vehicle 200 runs by using the electric power driving force transducer 203 as a power source. An example of the electric power driving force transducer 203 is a motor. The electric power driving force transducer 203 operates using the electric power of the battery 208 , and the rotational force of the electric power driving force transducer 203 is transferred to the driving wheels 204 a and 204 b . By using direct current-alternating current (DC-AC) or inverse conversion (AC-DC conversion) at a necessary place, the electric power driving force transducer 203 can use any of an AC motor and a DC motor. The various sensors 210 control the engine revolution speed through the vehicle control device 209 or controls the opening (throttle opening) of a throttle valve (not shown). The various sensors 210 include a speed sensor, an acceleration sensor, an engine revolution speed sensor, and the like.

The rotational force of the engine 201 is transferred to the power generator 202 , and the electric power generated by the power generator 202 by using the rotational force can be stored in the battery 208 .

When a hybrid vehicle decelerates by a braking mechanism (not shown), the resistance force at the time of the deceleration is added as a rotational force to the electric power driving force transducer 203 , and the regenerative electric power that is generated by the electric power driving force transducer 203 by using the rotational force is stored in the battery 208

The battery 208 , as a result of being connected to an external power supply of the hybrid vehicle, receives supply of electric power by using a charging slot 211 as an input slot from the external power supply, and can store the received electric power.

Although not shown in the figures, the present application may include an information processing apparatus that performs information processing for vehicle control on the basis of information on a secondary battery. Examples of such information processing apparatuses include an information processing apparatus that performs display of the remaining amount of a battery on the basis of the information on the remaining amount of the battery.

In the foregoing, a description has been given by using, as an example, a series hybrid car that runs using a motor by using electric power generated by a power generator that is driven by an engine or by using electric power that had once been stored in a battery. However, the present application can be effectively applied to a parallel hybrid car in which the outputs of both the engine and the motor are used as a driving source and in which switching between three methods, that is, running using only an engine, running using only a motor, and running using an engine and a motor, is performed as appropriate. In addition, the present application can be effectively applied to a so-called motor-driven vehicle that runs by driving using only a driving motor without using an engine.

It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.