Power supply system

This application claims priority from Korean Patent Application No. 10-2016-0090782 filed on Jul. 18, 2016 in the Korean Intellectual Property Office, and all the benefits accruing therefrom under 35 U.S.C. 119, the contents of which in its entirety are herein incorporated by reference.

1. Technical Field

Example embodiments of the inventive concepts relate to a power supply system.

2. Description of the Related Art

Generally, in order to stably supply power to semiconductor production equipment for reliable and continuous operation, an uninterruptible power supply (UPS) may be installed and operated as a buffer between a commercial power supply and production equipment. The UPS may primarily generate a DC power by AC-DC converting an AC power supplied to a power system to the DC power, and output an AC power by performing DC-AC converting the DC power to AC power via an inverter.

Meanwhile, by using an inverter for motor control in semiconductor manufacturing equipment, a load supplied with AC power is used to perform AC/DC conversion and DC/AC conversion in order to change the voltage and frequency of the AC power provided by the UPS. Therefore, there may be problems such as a reduction in power conversion efficiency due to an increase in the number of power conversion steps and an increase in maintenance burden due to an increase in the number of power conversion devices.

Example embodiments of the inventive concepts provide a power supply system capable of reducing the maintenance burden and increasing the power conversion efficiency by reducing the number of power conversion steps.

In some example embodiments of the inventive concepts, a power supply system may include a first rectifier configured to receive a first input AC power from a first input AC power source, to convert the first input AC power into a first DC power, and to output the first DC power to a connection node; one or more motors connected in parallel to the connection node, each of the one or more motors being connected to a respective one of one or more inverters, the one or more inverters configured to convert the DC power at the connection node into converted AC power, the one or more motors configured to receive the converted AC power; and an auxiliary power source configured to supply a second DC power to the connection node based on one or more of an interrupt in a supply of the first DC power and an overload condition of the one or more motors.

In some example embodiments of inventive concepts, a power supply system may include a first rectifier configured to receive an AC power from a first input AC power source, to convert the AC power into a first DC power, and to output the first DC power to a connection node; an auxiliary power source including a battery connected to the connection node through a chopper, the auxiliary power source configured to supply a second DC power to the connection node; one or more motors connected in parallel to the connection node through one or more inverters, respectively; and a controller configured to, determine whether to provide the first DC power and the second DC power to the connection node via the first rectifier and the chopper, respectively, and control a frequency and an output voltage of the one or more inverters.

In some example embodiments of inventive concepts, a power supply system includes a first rectifier connected to a connection node via a first switch, the first rectifier configured to perform AC-DC conversion on AC power generated by an AC power source to generate first DC power; an inverter connected to the connection node via a second switch, the inverter configured to perform DC-AC conversion on the first DC power or second DC power to generate converted AC power having one or more of a different voltage and frequency from the AC power, and to provide the converted AC power to a motor; and a controller configured to, selectively transmit the first DC power from the first rectifier to the connection node by closing the first switch, and selectively enable the inverter to convert the one or more of the first DC power and the second DC power to the converted AC power by closing the second switch.

However, example embodiments of the inventive concepts are not restricted to the one set forth herein. The above and other aspects of the example embodiments of the inventive concepts will become more apparent to one of ordinary skill in the art to which the inventive concepts pertains by referencing the detailed description of some example embodiments of the inventive concepts given below.

The above and other aspects and features of the present inventive concept will become more apparent by describing in detail some example embodiments thereof with reference to the attached drawings, in which:

FIG. 1 is a circuit diagram illustrating a power supply system according to an example embodiment of the inventive concepts;

FIGS. 2 to 6 are circuit diagrams illustrating an operation of the power supply system of FIG. 1 ;

FIG. 7 is a circuit diagram of a power supply system according to another example embodiment of the inventive concepts;

FIG. 8 is a circuit diagram of a power supply system according to still another example embodiment of the inventive concepts;

FIG. 9 is a circuit diagram of a power supply system according to still another example embodiment of the inventive concepts; and

FIG. 10 is a circuit diagram of a power supply system according to still another example embodiment of the inventive concepts.

FIG. 1 is a circuit diagram of a power supply system according to an example embodiment of the inventive concepts.

Referring to FIG. 1 , a power supply system 1 according to an example embodiment of the inventive concepts may include a first rectifier 10 , a second rectifier 11 , an auxiliary power source 20 , one or more loads (motors) 30 connected in parallel to a connection node N 1 and a power source 45 .

The first rectifier 10 may convert an AC power supplied from a first input AC power source 50 into a first DC power and supply the first DC power to the connection node N 1 . The first rectifier 10 may include, e.g., a pulse-width modulated (PWM) or thyristor rectifier, but the present inventive concept is not limited thereto.

A first switch S 1 connected to one end of the rectifier 10 may be turned on (short-circuited) to transmit the AC power supplied from a first transformer 100 to the rectifier 10 . Further, in the case of failing to provide DC power to the connection node N 1 due to an abnormal operation of the rectifier 10 and/or the transformer 100 , the first switch S 1 may be turned off (opened) to prevent AC power from being supplied to the rectifier 10 .

The auxiliary power source 20 may include a chopper 21 and a battery 22 . The chopper 21 may be a DC/DC converter configured to transform a second DC power supplied from the battery 22 according to the voltage level of the connection node N 1 , or provide a third DC power for charging the battery 22 by transforming the voltage level of the DC power provided to the connection node N 1 .

The battery 22 may be connected to one end of the chopper 21 to provide power to be supplied to the motors 30 . The battery 22 may include a group of battery cells containing a lithium-ion battery. In some example embodiments of the inventive concepts, the battery 22 may be included as an energy storage device in an energy storage system (ESS).

If the supply of AC power from the first input AC power source 50 is interrupted, or the supply of the first DC power to the connection node N 1 is interrupted due to an abnormal operation of the first rectifier 10 or the transformer 100 , the auxiliary power source 20 may supply the second DC power to the connection node N 1 .

Meanwhile, if all of first to third motors 30 _ 1 to 30 _ 3 are operated to cause an overload in the motors 30 , it may be impossible to provide enough power to drive the first to third motors 30 _ 1 to 30 _ 3 only with the first DC power generated by the first rectifier 10 . Therefore, in this case, the auxiliary power source 20 may supply the second DC power to the connection node N 1 . A specific operation of the auxiliary power source 20 will be described in more detail later with reference to FIGS. 2 to 5 .

If the supply of the first DC power from the first rectifier 10 and the third DC power from the auxiliary power source 20 are interrupted, a switch S 5 may be closed such that the second rectifier 11 may convert an AC power received from a second input AC power source 60 into a DC power and output the DC power to the connection node N 1 .

Further, if the first transformer 100 is operating abnormally while the first rectifier 10 is operating normally such that the first rectifier 10 can still convert AC power, a short-circuit switch SW may be switched to connect the AC power supplied from the second transformer 110 to the connection node N 1 .

To the connection node N 1 , in addition to the first rectifier 10 , the second rectifier 11 and the auxiliary power source 20 , one or more of the motors 30 may be connected through inverters INV 1 to INV 3 , switches S 2 to S 4 and automatic transfer switches (ATS) 31 . The motors 30 may include, for example, a first motor 30 _ 1 which rotates at the first number of revolutions, a second motor 30 _ 2 which rotates at the second number of revolutions, and a third motor 30 _ 3 which rotates at the third number of revolutions. The first to third numbers of revolutions may be the same or different from each other.

In order to rotate the first to third motors 30 _ 1 to 30 _ 3 at the first to third numbers of revolutions, the first to third inverters may provide AC powers having first to third frequencies to the first to third motors 30 _ 1 to 30 _ 3 , respectively. In other words, the first to third inverters INV 1 to INV 3 may convert the first or second DC power provided to the connection node N 1 into AC powers having first to third frequencies by DC/AC conversion and, then, provide the AC powers having the first to third frequencies to the first to third motors 30 _ 1 to 30 _ 3 .

Meanwhile, if the operation of the first to third motors 30 _ 1 to 30 _ 3 is stopped or the number of revolutions is reduced, that is, if an induced electromotive force is generated by regenerative braking, the first to third inverters INV 1 to INV 3 may provide a third DC power to the connection node N 1 by AC/DC conversion.

Although not shown in detail, the AC power provided from the input AC power source 50 to the rectifier 10 through the transformer 100 is a three-phase AC power, and accordingly a circuit between the input AC power source 50 and the rectifier 10 may also be a three-phase circuit.

If a voltage of the DC power supplied from the inverters INV 1 to INV 3 falls below a reference value, the ATS 31 may automatically serve as a backup power source to supply the power of a constant voltage to the motors 30 .

The power source 45 may produce and supply power to the connection node N 1 separately from the power supplied from the first power source 50 and the second power source 60 . For example, the power source 45 may include a new and renewable energy source such as solar or wind power.

FIGS. 2 to 6 are circuit diagrams illustrating an operation of the power supply system according to example embodiments of the inventive concepts.

Referring to FIG. 2 , when an abnormal condition or operation does not occur in the input AC power source 50 , the transformer 100 and the rectifier 10 , the switch S 1 is turned on, and the AC power AC 1 supplied from the input AC power source 50 and transformed by the transformer 100 is transmitted to the rectifier 10 through the switch S 1 . The rectifier 10 may convert the AC power AC 1 into a first DC power DC 1 and output the first DC power DC 1 to the connection node N 1 .

The first DC power DC 1 provided to the connection node N 1 may be converted into AC power to drive the motors 30 . For example, if the first and second motors 30 _ 1 and 30 _ 2 are required to be driven, only a second switch S 2 and a third switch S 3 may be turned on such that the first DC power DC 1 is provided to only the first and second inverters INV 1 and INV 2 . The first and second inverters INV 1 and INV 2 may convert portions DC 1 _ 1 and DC 1 _ 2 of the first DC power into AC powers AC 2 _ 1 and AC 2 _ 2 , and provide the AC powers AC 2 _ 1 and AC 2 _ 2 to the first and second motors 30 _ 1 and 30 _ 2 , respectively.

In this case, since the first DC power DC 1 is provided from the rectifier 10 and an overload does not occur in the motors 30 , the auxiliary power source 20 is disabled and the switch S 5 is open such that the DC power provided from the auxiliary power source 20 and the second rectifier 11 to the connection node N 1 is absent.

In the power supply system 1 according to an example embodiment of the inventive concepts, the AC power provided from the input AC power source 50 is AC-DC converted into the first DC power DC 1 primarily by the rectifier 10 . Then, the first DC power DC 1 is transmitted as direct current to the connection node N 1 . Further, the motors 30 may receive the AC power obtained by DC-AC converting the first DC power DC provided to the connection node N 1 via the inverters INV 1 to INV 3 . Thus, AC/DC conversion and DC/AC conversion are performed only once in order to provide the AC power AC 1 provided from the input AC power source 50 to the motors 30 _ 1 and 30 _ 2 through voltage and frequency conversion.

Accordingly, it is possible to reduce the power efficiency loss due to the AC/DC and DC/AC conversions which are repeated several times. Meanwhile, since the circuit elements can be used commonly for AC/DC and DC/AC conversions, it is possible to reduce the installation area and cost and facilitate the maintenance.

Referring to FIG. 3 , the first DC power DC 1 (see FIG. 2 ) may not be provided to the connection node N 1 due to an abnormal condition or operation in the input AC power source 50 , the transformer 100 and/or the rectifier 10 .

Also in this case, since the motors 30 should be driven continuously, the auxiliary power source 20 is enabled such that a second DC power DC 2 is provided from the auxiliary power source 20 to the connection node N 1 , and the first and second inverters INV 1 and INV 2 receive portions DC 2 _ 1 and DC 2 _ 2 of the second DC power, respectively.

Therefore, the first and second motors 30 _ 1 and 30 _ 2 can be driven by receiving AC powers AC 2 _ 1 and AC 2 _ 2 converted by the inverters INV 1 and INV 2 without interruption of power supply.

Meanwhile, the second DC power DC 2 provided from the auxiliary power source 20 to the connection node N 1 may be transmitted in the form of DC power to the inverters INV 1 to INV 3 . Thus, since the DC/AC conversion is unnecessary for transmission, when the supply of the first DC power DC 1 from the rectifier 10 is interrupted, the second DC power DC 2 may be provided immediately to the connection node N 1 .

Referring to FIG. 4 , while all of the first to third motors 30 _ 1 to 30 _ 3 are operated, an overload may occur in the motors 30 . In this case, the first DC power DC 1 provided by the first rectifier 10 may not be a sufficient to meet the power required by the first to third motors 30 _ 1 to 30 _ 3 .

Therefore, in one or more example embodiments, the auxiliary power source 20 may be enabled such that the auxiliary power source 20 may provide the second DC power DC 2 from the batter 22 to the connection node N 1 . The sum DC 3 of the first DC power DC 1 and the second DC power DC 2 may be transmitted to the inverters INV 1 to INV 3 , and AC powers AC 2 _ 1 to AC 2 _ 3 generated by DC/AC conversion may be transmitted to the first to third motors 30 _ 1 to 30 _ 3 , respectively.

Also in this case, similarly, since the first DC power DC 1 provided by the rectifier 10 and the second DC power DC 2 provided by the auxiliary power source 20 do not need to be converted into AC power by DC/AC conversion for transmission to the inverters INV 1 to INV 3 , it is possible to reduce the power loss due to the DC/AC conversion.

Referring to FIG. 5 , an induced electromotive force generated by regenerative braking due to a reduction in the number of revolutions or an interruption of rotation of the first to third motors 30 _ 1 to 30 _ 3 is transmitted, as first to third regenerative braking energies RE 1 to RE 3 , to the inverters INV 1 to INV 3 , respectively. The first to third inverters INV 1 to INV 3 generate a third DC power DC 4 by AC-DC converting the first to third regenerative braking energies RE 1 to RE 3 , respectively, and provide the third DC power DC 4 to the connection node N 1 .

The auxiliary power supply 20 may utilize the third DC power DC 4 to charge the battery 22 . That is, the third DC power is supplied to the chopper 21 and is stepped up or down to the charging voltage of the battery 22 to charge the battery 22 .

The auxiliary power supply 20 may have priority over the rectifier 10 in regards to receiving the third DC power DC 4 . If the charging of the battery 20 is completed, the third DC power DC 4 may be DC-AC converted via the rectifier 10 and provided as an AC power AC 3 to the input AC power source 50 . The AC power AC 3 provided to the input AC power source 50 may be returned to the power supply system.

According to the power supply system according to an example embodiment of the inventive concepts, the regenerative braking energies RE 1 to RE 3 generated by the first to third motors 30 _ 1 to 30 _ 3 may be AC-DC converted via the inverters INV 1 to INV 3 and transmitted to the connection node N 1 by direct current transmission. In other words, since there is no need to perform the voltage and frequency conversion for alternating current transmission of the first to third regenerative braking energies RE 1 to RE 3 to the connection node N 1 , it is possible to increase the power transmission efficiency of the energy generated by regenerative braking of the motors 30 and the charging efficiency of the battery 22 .

Separately from the regenerative braking of the motors 30 , the power generated from the power source 45 may be provided to the connection node N 1 . When the DC power generated from the power source 45 is provided to the connection node N 1 , the power supply system 1 may transmit the DC power to the auxiliary power source 20 , or transmit the DC power to the input AC power source 50 through the first rectifier 10 .

Referring to FIG. 6 , if the supply of DC power from the first rectifier 10 and the auxiliary power source 20 is interrupted, the switch S 5 may be closed such that the second rectifier 11 may receive an AC power AC 4 from the second input AC power source 60 and output a fifth DC power DC 5 to the connection node N 1 .

In other words, if the supply of DC power from the first rectifier 10 is interrupted, the supply of DC power from the auxiliary power source 20 is started primarily. However, the auxiliary power source 20 which outputs the charged power may fail to provide the power required to drive the motors 30 because of, for example, the capacity limit of the battery cell.

Accordingly, if the supply of DC power from the first rectifier 10 and the auxiliary power source 20 is interrupted, the switch S 5 is turned on and the fifth DC power DC 5 may be provided to the connection node N 1 through AC/DC conversion of the second rectifier 11 . Since the fifth DC power DC 5 provided to the connection node N 1 by the second rectifier 11 also does not need to be converted into AC power by DC/AC conversion for transmission to the inverters INV 1 to INV 3 , it is possible to increase the power transmission efficiency.

The second rectifier 11 may include a different configuration from the first rectifier 10 . That is, the second rectifier 11 may include a configuration in consideration of the characteristics of the second rectifier 11 whose driving time is shorter than that of the first rectifier 10 .

Although not shown in detail, the AC power provided from the second input AC power source 60 to the second rectifier 11 through a second transformer 110 is a three-phase AC power, and accordingly a circuit between the second input AC power source 60 and the rectifier 11 may also be a three-phase circuit.

Alternatively, although not shown, the short-circuit switch SW may be used to provide the AC power from the second input AC power source 60 to the first rectifier 10 such that the first rectifier 10 provides the DC current to the connection node N 1 after AC/DC conversion. In other words, if there is no problem in the operation of the first rectifier 10 although an abnormal operation occurs in the first transformer 100 , the AC power supplied from the second transformer 110 may be inputted through the short-circuited switches SW and S 1 and provided to the connection node N 1 .

FIG. 7 is a circuit diagram of a power supply system according to another example embodiment of the inventive concepts.

Referring to FIG. 7 , a power supply system 2 according to another example embodiment of the inventive concepts may further include first and second loads L 1 and L 2 additionally connected to the connection node N 1 , choppers or inverters 121 and 122 for supplying DC or AC power to the first and second loads L 1 and L 2 , first and second rectifiers 10 and 11 , an auxiliary power source 20 , motors 30 and a controller 150 for controlling the first and second loads L 1 and L 2 .

The first and second loads L 1 and L 2 additionally connected to the connection node N 1 may be electric devices which are supplied with DC or AC power. The following description will be given on the assumption that the first load L 1 is supplied with AC power and the second load L 2 is supplied with DC power, but example embodiments of the inventive concepts are not limited thereto.

The first load L 1 may be a lighting device which is driven by being supplied with AC power. If the first load L 1 is a motor, the fifth switch S 5 and the inverter 121 may be connected between the first load L 1 and the connection node N 1 . The inverter 121 may be supplied with DC power from the connection node N 1 , and may convert the DC power into AC power and supply the AC power to the first load L 1 . In this case, the frequency of the AC power supplied to the first load L 1 may be different from the frequency of the power supplied to the motors 30 .

The second load L 2 may be, for example, an electronic device which is driven by being supplied with DC power. If the second load L 2 is a computer that is driven by DC power, a sixth switch S 6 and the chopper 122 may be connected between the second load L 2 and the connection node N 1 . The chopper 122 may be supplied with DC power from the connection node N 1 , and may provide the DC power to the second load L 2 after converting the magnitude of the DC power.

The controller 150 may include a first controller 151 for controlling the first and second rectifiers 10 and 11 and the auxiliary power source 20 which supply DC power to the connection node N 1 , and a second controller 152 for controlling inverters 35 which are connected to one or more motors 30 connected in parallel to the connection node N 1 , the inverter 121 which supplies the AC power to the first load L 1 and the chopper 122 which supplies the DC power to the second load L 2 .

However, example embodiments are not limited thereto, for example in some example embodiments a same common controller 150 may control the entire power supply system 2 .

The first controller 151 may control the first rectifier 10 by generating and transmitting a first rectifier control signal REC 1 . For example, the first controller 151 may monitor whether the input AC power source 50 normally supplies the AC power and whether the first transformer 100 is operated normally, and determines whether the first rectifier 10 performs an AC/DC conversion operation. That is, if the input AC power is not provided due to a problem of the input AC power source 50 or a problem of the first transformer 100 , the first controller 151 may control the first rectifier 10 by instructing the first switch S 1 to cut off an electric connection between the first transformer 100 and the first rectifier 10 to stop the operation of the first rectifier 10 .

Meanwhile, the first controller 151 may control the auxiliary power source 20 by using a chopper control signal CHOP_CON and a battery control signal BAT_CON. For example, the first controller 151 may instruct the chopper 21 to convert the voltage charged in the battery based on the chopper control signal CHOP_CON and to provide the converted voltage to the connection node N 1 . Further, the first controller 151 may monitor the voltage and current levels of the battery 22 while controlling the charging and discharging of the battery and an operation of absorbing the regenerative braking energy based on the battery control signal BAT_CON.

If the AC/DC conversion operation is not performed by the first rectifier 10 , the first controller 151 may instruct the auxiliary power supply 20 to provide the second DC power DC 2 (see FIG. 3 ) from the battery 22 to the connection node N 1 by using the battery control signal BAT_CON. In this case, the first controller 151 may control the chopper 21 by using the chopper control signal CHOP_CON, thereby generating the second DC power DC 2 by converting the voltage of the DC power supplied from the battery 22 .

Meanwhile, as a result of monitoring the level of the voltage charged in the battery 22 , if the voltage level of the battery 22 falls below a desired (or, alternatively, a predetermined) level, the first controller 151 may control the second rectifier 11 and the fifth switch S 5 , thereby converting the second AC power from the second input AC power source 60 and providing the converted AC power to the connection node N 1 . At the same time, the first controller 151 may interrupt the supply of the second DC power from the auxiliary power source 20 by using the chopper control signal CHOP_CON and the battery control signal BAT_CON.

The second controller 152 may control the inverter 35 by using a motor control signal MOT_CON, and determine the frequency and the magnitude of the voltage of the AC power provided to the motors 30 by DC/AC conversion of the inverters 35 . According to the motor control signal MOT_CON, the frequency and the magnitude of the voltage of the AC power provided to the motors 30 by DC/AC conversion of the inverters INV 1 to INV 3 may be different. Further, the second controller 152 may control the first inverter INV 1 such that the first inverter INV 1 outputs the AC power having a frequency r 1 at a first time point and outputs the AC power having a frequency r 2 at a second time point.

Meanwhile, if the operation of the first to third motors 30 _ 1 to 30 _ 3 is stopped or the number of revolutions is reduced, that is, if an induced electromotive force is generated by regenerative braking, the second controller 152 may control the first to third inverters INV 1 to INV 3 to provide the third DC power to the connection node N 1 by AC/DC conversion of the AC power caused by the generated induced electromotive force.

FIG. 8 is a circuit diagram of a power supply system according to still another example embodiment of the inventive concepts.

Referring to FIG. 8 , a power supply system 3 according to still another embodiment of the present inventive concept may include a plurality of DC power supply systems 15 _ 1 to 15 _ 3 .

The first to third DC power supply systems 15 _ 1 to 15 _ 3 may include first rectifiers 10 _ 1 to 10 _ 3 which are connected to the first transformer 100 , and second rectifiers 11 _ 1 to 11 _ 3 and auxiliary power sources 20 _ 1 to 20 _ 3 which are connected to the second transformer 110 , respectively.

The DC power supply systems 15 _ 1 to 15 _ 3 may supply DC powers from the first rectifiers 10 _ 1 to 10 _ 3 , the second rectifiers 11 _ 1 to 11 _ 3 or the auxiliary power sources 20 _ 1 to 20 _ 3 to connection nodes N 1 _ 1 to N 1 _ 3 , respectively.

That is, while each of the power supply systems 1 and 2 according to the above-described embodiments includes only one DC power supply system having the first rectifier 10 , the second rectifier 11 and the auxiliary power source 20 , in the present embodiment, the power supply system 3 may include the DC power supply systems 15 _ 1 to 15 _ 3 connected in parallel.

The first DC power supply system 15 _ 1 and the second DC power supply system 15 _ 2 may simultaneously supply DC powers to the motors 30 . That is, as switches S 1 _ 1 and S 1 _ 2 are short-circuited, DC powers can be simultaneously supplied to the motors 30 from the first rectifiers 10 _ 1 and 10 _ 2 in the DC power supply systems connected in parallel.

In this case, the third DC power supply system 15 _ 3 may operate differently from the other DC power supply systems 15 _ 1 and 15 _ 2 . In other words, the third DC power supply system 15 _ 3 may operate only when the operations of the first and second DC power supply systems 15 _ 1 and 15 _ 2 are stopped to supply the power to the motors 30 without operating at the same time with the first and second DC power supply systems 15 _ 1 and 15 _ 2 .

The power supply system illustrated in FIG. 8 is merely exemplary, and the power supply system 3 may include, for example, n+1 DC power supply systems such that n DC power supply systems are operated simultaneously and the other one is operated preliminarily.

FIG. 9 is a circuit diagram of a power supply system according to still another example embodiment of the inventive concepts.

Referring to FIG. 9 , a power supply system 4 according to still another embodiment of the present inventive concept may include an emergency rectifier 16 connected to the first transformer 100 in place of the third DC power supply system 15 _ 3 included in the power supply system 3 illustrated in FIG. 8 .

The emergency rectifier 16 may operate similarly to the third DC power supply system 15 _ 3 of FIG. 8 . That is, generally, the first and second DC power supply systems 15 _ 1 and 15 _ 2 are operated simultaneously, and the emergency rectifier 16 may not operate at the same time with the first and second DC power supply systems 15 _ 1 and 15 _ 2 . The emergency rectifier 16 may be supplied with AC power from the input AC power source 50 , only when the operations of the first and second DC power supply systems 15 _ 1 and 15 _ 2 are stopped, to supply the power to the motors 30 .

In this respect, the emergency rectifier 16 may supply the DC power of the capacity greater than the rectifiers 10 _ 1 , 10 _ 2 , 11 _ 1 and 11 _ 2 included in the first and second DC power supply systems 15 _ 1 and 15 _ 2 .

Similarly to the power supply system 3 of FIG. 8 , the power supply system 4 of FIG. 9 may include two or more DC power supply systems. The power supply system 4 may be configured such that n DC power supply systems are connected in parallel to the first input AC power sources 50 and the second input AC power source 60 and the emergency rectifier 16 is connected to the input AC power source 50 .

FIG. 10 is a circuit diagram of a power supply system according to still another example embodiment of the present inventive concepts.

Referring to FIG. 10 , a power supply system 5 according to still another example embodiment of the inventive concepts may include a third input AC power source 70 and a third transformer 120 connected to the ATS 31 .

That is, if the voltage of the AC power received from the inverters INV 1 to INV 3 does not reach the voltage required by the first to third motors 30 _ 1 to 30 _ 3 for any reason, the first to third motors 30 _ 1 to 30 _ 3 may not operate normally. In this case, the ATS 31 may receive power from the third input AC power source 70 serving as a backup power source and supply the power to the first to third motors 30 _ 1 to 30 _ 3 after cutting off the connection between the inverters INV 1 to INV 3 and the first to third motors 30 _ 1 to 30 _ 3 .

Some example embodiments of the present inventive concepts have been described with reference to the attached drawings, but it may be understood by one of ordinary skill in the art that example embodiments of the inventive concepts may be performed one of ordinary skill in the art in other specific forms while keeping with the spirit of the inventive concepts. Further, the above-described example embodiments are merely examples and do not limit the scope of the rights of the inventive concepts.