TWI740506B - Power conversion device and power supply system - Google Patents

Abstract

A power conversion device includes a power source, a converter, a current detection circuit, and a control circuit. The power source includes positive and negative terminals. The converter includes a primary side and a secondary side. The converter is configured to output a first current to the load. The primary side is electrically connected to the positive terminal and the negative terminal of the power source in parallel. The secondary side is electrically connected to the positive terminal of the power source and the load in series. The current detection circuit is coupled between the secondary side and the load, and is configured to detect the first current to output a current detection signal. The control circuit is coupled to the detection circuit for outputting a control signal to the converter according to the current detection signal and a reference current signal.

Description

Power conversion device and power supply system

The present disclosure relates to a power conversion device and a power supply system, and more particularly to a power conversion device using a transformer and a power supply system including a plurality of power conversion devices.

When multiple batteries are used in parallel, due to the difference in internal resistance, capacity and aging of each battery, the output current of each battery cannot be shared, and the discharge time will be limited by the lowest capacity of these batteries. One.

Generally speaking, in order to achieve current sharing, a DC converter is connected to the output terminal of each battery, and the output current is consistent by controlling the output voltage. However, in order to achieve high-power discharge, the DC converter requires a relatively high component specification, a large volume, low conversion efficiency, and is prone to overheating.

Therefore, how to maintain current sharing and solve the above-mentioned problems is one of the important issues in this field.

One aspect of the present disclosure relates to a power conversion device. The power conversion device is used to provide output voltage and output current to the load, and it includes a power supply and a converter. The power supply is used to provide the first voltage. The converter includes a switch and a transformer, and the transformer includes a primary winding and a secondary winding. The primary winding is connected to the switch in series and used to receive the first voltage, wherein the primary winding and the switch are connected in parallel to the power source. The secondary winding connects the power source and the load in series. The switch is used for switching according to the control signal, so that the secondary winding generates the second voltage according to the voltage of the primary winding. The sum of the first voltage and the second voltage is used as the output voltage.

Another aspect of the present disclosure relates to a power supply system. The power supply system includes a plurality of power conversion devices for respectively providing output voltage and output current to the load. Each of the power conversion devices includes a power supply, an inverter, and a control circuit. The power supply is used to output the first voltage. The converter includes a switch and a transformer, and the transformer includes a primary winding and a secondary winding. The primary winding is connected to the switch in series and used to receive the first voltage, wherein the primary winding and the switch are connected in parallel to the power source. The secondary winding connects the power source and the load in series. The switch is used for switching according to the control signal, so that the secondary winding generates the second voltage according to the voltage of the primary winding. The control circuit is used for generating a control signal according to the current detection signal and the reference current signal of the corresponding output current, so as to control the switch to adjust the second voltage so that the output voltages of the power conversion devices are equal.

In summary, by electrically connecting the DC power supply to the secondary winding of the transformer, the transformer only needs to convert the voltage difference between the supply voltage of the DC power supply and the target output voltage, which can reduce the cost of components, reduce the volume of the finished product, and Improve conversion efficiency, reduce over-temperature problems, and effectively extend the overall discharge time.

The following is a detailed description of the embodiments in conjunction with the accompanying drawings. However, the specific embodiments described are only used to explain the case, and are not used to limit the case. The description of the structural operations is not used to limit the order of its execution. The recombined structures and the devices with equal effects are all within the scope of this disclosure.

Unless otherwise specified, the terms used in the entire specification and the scope of the patent application usually have the usual meaning of each term used in this field, in the content disclosed here, and in the special content. Some terms used to describe the present disclosure will be discussed below or elsewhere in this specification to provide those skilled in the art with additional guidance on the description of the present disclosure.

In addition, the terms "include", "include", "have", "contain", etc. used in this article are all open terms, meaning "including but not limited to". In addition, the "and/or" used in this article includes any one or more of the related listed items and all combinations thereof.

In this text, when an element is referred to as "connection" or "coupling", it can refer to "electrical connection" or "electrical coupling". "Connected" or "coupled" can also be used to mean that two or more components cooperate or interact with each other. In addition, although terms such as “first”, “second”, etc. are used to describe different elements in this document, the terms are only used to distinguish elements or operations described in the same technical terms. Unless the context clearly indicates, the terms do not specifically refer to or imply order or sequence, nor are they used to limit the present invention.

Please refer to Figure 1. FIG. 1 is a schematic diagram of a power supply system 100a according to some embodiments of the present disclosure. As shown in Fig. 1, the power supply system 100a includes a plurality of power conversion devices MOD1 to MODn. The power conversion devices MOD1 to MODn are connected in parallel with each other, and are all electrically connected to the load LOAD, and respectively provide output currents to the load LOAD.

As shown in FIG. 1, the power conversion device MOD1 includes a power supply B1, an inverter 111, a current detection circuit 141, a voltage detection circuit 181, and a control circuit CON1. The power supply B1 includes a positive terminal and a negative terminal. The inverter 111 includes a primary side Np1 and a secondary side Ns1. In some embodiments, the power source B1 may be a DC power source and implemented by a battery, but this case is not limited to this. In this embodiment, the converters 111 to 110n are used to provide positive voltage compensation to the output voltages of the respective power conversion devices MOD1 to MODn, and the specific circuit structure can also refer to FIG. 2A.

Structurally, the positive terminal of the power source B1 is connected to the node Na11 through the resistor R1, and the negative terminal of the power source B1 is connected to the node Na21 and grounded. The first end of the primary side Np1 is connected to the node Na11, and the second end of the primary side Np1 is connected to the node Na21. In other words, the primary winding side Np1 is connected to the power source B1 in parallel. The first end of the secondary side Ns1 is connected to the node Nb11, and the second end of the secondary side Ns1 is connected to the node Nb21. In other words, the secondary winding Ns1 connects the power source B1 and the load LOAD in series. The current detection circuit 141 and the voltage detection circuit 181 are both connected between the node Nb21 and the load LOAD.

In operation, the primary side Np1 of the converter 111 is used to receive the first voltage, and the secondary side Ns1 is used to generate the second voltage according to the voltage of the primary side Np1. Since the secondary side Ns1 of the converter 111 is connected to the power source B1 in series, the first voltage of the power source B1 is superimposed on the second voltage generated by the secondary side of the converter 111 and is collectively provided as an output voltage to the load LOAD current. The detection circuit 141 is used for detecting the first current I1 (that is, the output current) output by the output terminal (that is, the node Nb21) of the secondary side Ns1 to output the current detection signal DI1 to the control circuit CON1. The voltage detection circuit 181 is used to detect the voltage (ie, the output voltage) of the output terminal (ie, the node Nb21) of the secondary side Ns1 to output a voltage detection signal DV1 to the control circuit CON1. The control circuit CON1 is used to receive and output a control signal CS1 to the converter 111 according to the current detection signal DI1, the reference current signal RI1 and the voltage detection signal DV1. The converter 111 is used for receiving and operating according to the control signal CS1.

In addition, the structure of the power conversion device MOD2 to MODn is similar to the structure of the power conversion device MOD1, which will not be repeated here.

Wherein, the reference current signals RI1 to RIn are the average values of the first currents I1 to In. In other words, the control circuits CON1 to CONn add and average the first currents I1 to In output by each of the converters 111 to 110n, and then transmit the average current value to each of the control circuits CON1 to CONn. In this way, each of the power conversion devices MOD1 to MODn uses the current average value as a reference to regulate the first current I1 to In that it outputs, so as to achieve the purpose of current sharing. At the same time, the output voltages provided to the load LOAD by the respective power conversion devices MOD1 to MODn are made the same.

In some embodiments, the control circuits CON1 to CONn can be implemented by various processing circuits, digital signal processors (DSP), complex programmable logic devices (CPLD), and field programmable gate arrays ( Field-programmable gate array, FPGA) and other methods are implemented.

Generally speaking, if the output voltage to be generated is 10 volts, and the first voltage output by the DC power supply is 8 volts, the converter of the conventional power conversion device needs to convert 8 volts into 10 volts through switching. . However, since the power supply B1～Bn of this case and the secondary side Ns1～Ns of the converter 111～110n are directly connected in series, the second voltage generated by the secondary side Ns1～Ns and the first voltage of the DC power supply B1～Bn are used together as the output voltage . Therefore, it is only necessary to control the converters 111 to 110n to generate a second voltage of 2 volts (instead of 10 volts), and the output voltage can still reach 10 volts.

In this way, since the converters 111-110n only need to convert the voltage difference between the first voltage and the target output voltage, the requirements for the components of the converters 111-110n are lower, which can reduce the cost, reduce the volume of the finished product, and convert The efficiency is higher and the problem of over-temperature can be alleviated.

For further details, please refer to Figure 2A. FIG. 2A is a schematic circuit diagram of the power conversion device MOD1 according to an embodiment of FIG. 1. FIG. Since the connection modes and operations of each of the power conversion devices MOD1 to MODn are similar, in order to simplify the description, the power conversion device MOD1 will be used as an example for description in FIG. 2A. In other words, the power conversion devices MOD2 to MODn in Figure 1 can all be implemented based on the power conversion device MOD1a in Figure 2A.

As shown in FIG. 2A, in some embodiments, the converter 111 can be implemented by a Flyback converter, but it is not necessary to limit this case. In other words, those skilled in the art can implement other converter circuits including transformers according to actual needs, such as forward converters, push-pull converters, and so on.

In this embodiment, the converter 111 includes a transformer (including a primary winding Np1 and a secondary winding Ns1), a switch SW0, a diode D1, and a capacitor C1. Structurally, the first end of the primary winding Np1 is connected to the node Na11. The second end of the primary winding Np1 is connected to the node Na21 through the switch SW0. The first end of the secondary winding Ns1 is connected to the anode end of the diode D1. The cathode end of the diode D1 is connected to the load LOAD through the node Nb11. The second end of the secondary winding Ns1 is connected to the node Na11 (that is, the positive terminal of the power source B1) via the node Nb21. The capacitor C1 is connected between the node Nb11 and the node Nb21.

In operation, the switch SW0 receives the control signal CS1 and switches according to the control signal CS1 to adjust the second voltage on the secondary winding Ns1. In this embodiment, the negative potential of the second voltage is on the node Nb21 and the secondary winding Ns1 is connected to the power source B1 in series via the nodes Nb21 and Na11, so the second voltage can be used as a positive voltage compensation of the output voltage. In other words, the output voltage provided by the power conversion device MOD1a can be greater than or equal to the first voltage provided by the power B1, and the control circuit CON1 can adjust the second voltage through the control signal CS1 so that the output voltage reaches the target voltage required by the load LOAD.

In addition, as shown in FIG. 2A, the control circuit CON1 includes a current sharing loop 161, a compensator 121, and a controller 131. Structurally, the current sharing loop 161 is coupled to the current detecting circuit 141 and current sharing loops of other power conversion devices. The compensator 121 is coupled to the voltage detection circuit 181 and the current sharing circuit 161. The controller 131 is coupled to the compensator 121 and the switch SW0.

In operation, the current sharing circuit 161 is used to receive the current detection signal DI1 and the reference current signal RI1, and generate a current difference DE1 according to the current detection signal DI1 and the reference current signal RI1. The compensator 121 is used to receive the voltage detection signal DV1 and the current difference DE1, and generate a compensation signal CC1 according to the voltage detection signal DV1 and the current difference DE1 to output to the controller 131. The controller 131 is used for receiving the compensation signal CC1 and generating a control signal CS1 according to the compensation signal CC1. In some embodiments, the control signal CS1 is a pulse width modulation signal (Pulse Width Modulation, PWM).

For example, when the current detection signal DI1 is greater than the reference current signal RI1, the compensator 121 generates a negative compensation signal CC1 according to the current difference DE1 greater than zero, so that the controller 131 adjusts the control according to the negative compensation signal CC1 The duty cycle of the signal CS1 is used to reduce the first current I1 (that is, the output current) and the voltage of the secondary winding Ns1 (that is, the second voltage). Conversely, when the current detection signal DI1 is less than the reference current signal RI1, the compensator 121 generates a positive compensation signal CC1 according to the current difference DE1 less than zero, so that the controller 131 increases the control signal CS1 according to the positive compensation signal CC1 The duty cycle to increase the first current I1 and the second voltage.

In addition, as shown in Figures 3B and 3C, when the first voltages V1 to Vn decrease as the discharge time increases, the second voltage (that is, the cross voltage V1b to Vnb) will increase as the discharge time increases to minimize It is possible to maintain the output voltage. For example, if the target voltage is 10 volts, when the first voltage Vn of the power source Bn is 8 volts, the second voltage Vnb needs to be 2 volts. When the first voltage Vn of the power source Bn decreases to 6 volts as the discharge time increases, the second voltage Vnb needs to be 4 volts. In other words, as the discharge time increases, the duty cycle of the control signal can be adjusted by the control circuits CON1 to CONn to control the first current I1 to In and the output voltage.

In this way, by detecting the respective first current I1~In and output voltage of each power conversion device MOD1~MODn, and performing compensation and regulation through the respective control circuits CON1~CONn, the first current I1~ In remains consistent with each other, as shown in Figure 3A.

Please refer to Figure 4. FIG. 4 is a schematic diagram showing another power supply system 100b according to some embodiments of the present disclosure. In the embodiment shown in Fig. 4, similar elements to those in the embodiment shown in Fig. 1, Fig. 2A and Fig. 2B are denoted by the same element symbols. The operations have been described in the previous paragraphs and will not be omitted here. Go into details. In this embodiment, the converters 111 to 110n are used to provide negative voltage compensation to the output voltages of the respective power conversion devices MOD1 to MODn, and the specific circuit structure can also refer to FIG. 2B.

As shown in FIG. 2B, the inverter 111 still uses a flyback inverter as an example. Structurally, the first end of the secondary winding Ns1 is connected to the anode end of the diode D1. The cathode terminal of the diode D1 is connected to the node Na11 (that is, the positive terminal of the power source B1) via the node Nb11. The second end of the secondary winding Ns1 is connected to the load LOAD via the node Nb21. The capacitor C1 is connected between the node Nb11 and the node Nb21. In this embodiment, the positive potential of the second voltage is on the node Nb11 and the secondary winding Ns1 is connected to the power supply B1 in series via the nodes Nb11 and Na11, so the second voltage can be used as a negative voltage compensation of the output voltage. In other words, the output voltage provided by the power conversion device MOD1b may be less than or equal to the first voltage provided by the power B1.

Please refer to Figure 5. FIG. 5 is a schematic diagram showing another power supply system 100c according to some embodiments of the present disclosure. In the embodiment shown in Fig. 5, the components similar to those in the embodiment of Fig. 1, Fig. 2A, Fig. 2B, and Fig. 4 are denoted by the same element symbols, and the operations have been described in the previous paragraphs. I will not repeat them here. The embodiment in FIG. 5 is based on a further variation of the architecture of FIG. 1. At least one of the power conversion devices MOD1 to MODn further includes a set of full bridge circuits. This embodiment takes as an example that all the power conversion devices MOD1 to MODn include a full-bridge circuit, but it is not limited to this. As shown in FIG. 5, the full bridge circuit is coupled to the secondary windings Ns1 to Nsn of the transformer (not shown) of each of the converters 111 to 110n.

Taking the power conversion device MOD1 as an example, the full bridge circuit includes a switch SW11, a switch SW21, a switch SW31, and a switch SW41. The first end of the switch SW11 is coupled to the node Nb11 (ie, the first end of the secondary winding Ns1). The second end of the switch SW11 is coupled to the node Na11. The first end of the switch SW21 is coupled to the node Na11. The second end of the switch SW21 is coupled to the node Nb21 (ie, the second end of the secondary winding Ns1). The first end of the switch SW31 is coupled to the node Nb11 (ie, the first end of the secondary winding Ns1). The second end of the switch SW31 is coupled to the load LOAD. The first end of the switch SW41 is coupled to the load LOAD. The second end of the switch SW41 is coupled to the node Nb21 (ie, the second end of the secondary winding Ns1).

In operation, when the positive voltage compensation is to be performed, the switch SW11 and the switch SW41 are closed (ie, turned on), and the switch SW21 and the switch S31 are turned on (ie, turned off). On the other hand, when the negative voltage compensation is to be performed, the switch SW21 and the switch S31 are closed (ie, turned on), and the switch SW11 and the switch SW41 are turned on (ie, turned off). In this way, by adding a full-bridge circuit, it is possible to realize positive or negative voltage compensation with a single topology. Similarly, a full-bridge circuit can also be added to the architecture of Figure 4 to realize a single topology for positive or negative voltage compensation. The specific details are similar to those described above and will not be repeated here.

Please refer to Figure 6. FIG. 6 is a schematic diagram showing another power supply system 100d according to some embodiments of the present disclosure. In the embodiment shown in Fig. 6, the components similar to those in the embodiment shown in Fig. 1, Fig. 2A, Fig. 2B, Fig. 4, and Fig. 5 are denoted by the same reference numerals, and their operations have been previously The description of the paragraph will not be repeated here. Compared with the embodiment in FIG. 5, in the embodiment in FIG. 6, the converters 111 to 110n in each power conversion device MOD1 to MODn are based on bi-directional isolated converters. Implement.

In this embodiment, the power conversion devices MOD1 to MODn further include switches 171 to 170n, respectively. The converters 111 to 110n are respectively used to receive the second currents S1 to Sn from the load LOAD to charge the power sources B1 to Bn. Specifically, taking the power conversion device MOD1 as an example, one end of the switch 171 is connected to the node Nb21 (that is, the second end of the secondary winding), and the other end is grounded. When the power supply B1 is to be charged, the switch SW31 and the switch 171 will be closed (ie, turned on), and the switch SW11, the switch SW21, and the switch SW41 will be turned on (ie, turned off). In this way, the converter 111 can receive the energy from the load LOAD and adjust the output voltage according to the demand of the power supply B1.

Please refer to Figure 7. FIG. 7 is a schematic diagram showing another power supply system 100e according to some embodiments of the present disclosure. In the embodiment of FIG. 7, the power supply system 100e includes power conversion devices MOD1 to MODn and power supply modules PSU1 to PSUn. The power conversion devices MOD1 to MODn and the power supply modules PSU1 to PSUn are connected in parallel with each other, and are electrically connected to the load LOAD. Each of the power conversion devices MOD1 to MODn can be implemented by any one of the power conversion devices shown in FIG. 1, FIG. 4, FIG. 5, and FIG. 6. In other words, the power conversion devices MOD1 to MODn are used to output the first currents I1 to In according to the reference current signals RI1 to RIn, or to receive the second currents S1 to Sn, respectively.

In addition, the power supply modules PSU1 to PSUn are respectively used to provide third currents Ip1 to Ipn according to the reference current signals RIp1 to RIpn. In some embodiments, each of the reference current signals RI1 ˜RIn and the reference current signals RIp1 ˜RIpn may be an average value of the first current I1 ˜In and the third current Ip1 ˜Ipn. Each power conversion device MOD1 to MODn and each power supply module PSU1 to PSUn uses the current average value as a reference to regulate the first or third current output to the load LOAD, so as to achieve current sharing.

In other embodiments, each of the reference current signals RI1 to RIn may be an average value of the third currents Ip1 to Ipn. The power supply modules PSU1 to PSUn provide the third currents Ip1 to Ipn to the load LOAD and the power conversion devices MOD1 to MODn according to the reference current signals RIp1 to RIpn, so that the power conversion devices MOD1 to MODn receive the second currents S1 to Sn for charging.

In other words, the power supply system 100e can implement positive voltage compensation, negative voltage compensation, and/or charging and discharging functions under a single topology, and can be applied in parallel with other power supply modules.

It is worth noting that although the power supply systems 100a, 100b, 100c, 100d, and 100e show a load LOAD, n power conversion devices MOD1～MODn, and n power supply modules PSU1～PSUn, where n is a positive integer , But the number is only an example for the convenience of description, and is not intended to limit the content of this disclosure. In some other embodiments, the power supply system may also include multiple loads. In addition, those with ordinary knowledge in the art can set the respective numbers of power conversion devices and power supply modules in the power supply system according to actual needs.

It should be noted that, in the case of no conflict, the features and circuits in the various drawings, embodiments, and embodiments of the present disclosure can be combined with each other. The circuit shown in the drawing is only an example, and is simplified to make the description concise and easy to understand, and is not intended to limit the case. In addition, the various devices, units, and components in the foregoing embodiments can be implemented by various types of digital or analog circuits, and can also be implemented by different integrated circuit chips, or integrated into a single chip. The foregoing is only an example, and the present disclosure is not limited thereto.

In summary, by applying the above embodiments, the power supplies B1 to Bn are electrically connected in series to the secondary sides Ns1 to Nsn of the converters 111 to 110n, so that the converters 111 to 110n only need to convert the power source B1. The voltage difference between the supply voltage of ~Bn and the target output voltage can reduce the cost of components, reduce the volume of the finished product, improve the conversion efficiency, reduce the over-temperature problem, and effectively extend the overall discharge time. In addition, the power supply system in this case can be applied to DC power supplies with different internal resistances and different degrees of aging, and can be compatible with other power supply modules or backup devices.

Although the content of this disclosure has been disclosed in the above manner, it is not intended to limit the content of this disclosure. Those with ordinary knowledge in the technical field can make various changes and modifications without departing from the spirit and scope of this disclosure. Therefore, this The scope of protection of the disclosed content shall be subject to the scope of the attached patent application.

100a, 100b, 100c, 100d, 100e: power supply system MOD1, MOD1a, MOD1b, MOD2, MODn: power conversion device CON1, CON2, CONn: control circuit B1, B2, Bn: power supply R1, R2, Rn: resistance Na11, Na21, Nb11, Nb21, Na12, Na22, Nb12, Nb22, Na1n, Na2n, Nb1n, Nb2n: node Np1, Np2, Npn: primary winding/primary side Ns1, Ns2, Nsn: secondary winding/secondary side 111, 112, 110n: converter 121, 122, 120n: compensator 131, 132, 130n: Controller 141, 142, 140n: Current detection circuit 161,162,160n: current sharing loop 181, 182, 180n: voltage detection circuit I1, I2, In: first current DI1, DI2, DIn: current detection signal DV1, DV2, DVn: voltage detection signal RI1, RI2, RIn, RIp1, RIp2, RIpn: reference current signal CS1, CS2, CSn: control signal LOAD: load SW0, SW11, SW21, SW31, SW41, SW12, SW22, SW32, SW42, SW1n, SW2n, SW3n, SW4n, 171, 172, 170n: switch V1a, V1b: cross voltage D1: Diode C1, C2, Cn: Capacitance DE1, DE2, DEn: current difference CC1: Compensation signal S1, S2, Sn: second current PSU1, PSU2, PSUn: power supply module Ip1, Ip2, Ipn: third current

FIG. 1 is a schematic diagram of a power supply system according to some embodiments of the present disclosure. FIG. 2A is a schematic circuit diagram of the power conversion device according to an embodiment of FIG. 1. FIG. FIG. 2B is a schematic circuit diagram of the power conversion device according to another embodiment of FIG. 1. FIG. FIG. 3A is a schematic diagram illustrating the output current of a power supply system according to some embodiments of the present disclosure. FIG. 3B is a schematic diagram of a DC power supply of a power supply system according to some embodiments of the present disclosure. FIG. 3C is a schematic diagram illustrating the induced voltage of a power supply system according to some embodiments of the present disclosure. Figures 4 to 7 are schematic diagrams respectively showing another power supply system according to some embodiments of the present disclosure.

100a: power supply system

MOD1, MOD2, MODn: power conversion device

CON1, CON2, CONn: control circuit

B1, B2, Bn: power supply

R1, R2, Rn: resistance

Na11, Na21, Nb11, Nb21, Na12, Na22, Nb12, Nb22, Na1n, Na2n, Nb1n, Nb2n: node

Np1, Np2, Npn: primary winding

Ns1, Ns2, Nsn: secondary winding

111, 112, 110n: converter

141, 142, 140n: Current detection circuit

181, 182, 180n: voltage detection circuit

I1, I2, In: first current

DI1, DI2, DIn: current detection signal

DV1, DV2, DVn: voltage detection signal

RI1, RI2, RIn: Reference current signal

CS1, CS2, CSn: control signal

LOAD: load

Claims (19)

A power conversion device for providing an output voltage and an output current to a load. The power conversion device includes: a power supply for providing a first voltage; a converter including: a switch; and a transformer including : A primary winding connected in series to the switch to receive the first voltage, wherein the primary winding and the switch are connected in parallel to the power supply; a secondary winding is connected in series to the power supply and the load; wherein the switch is used to control Signal switching, so that the secondary winding generates a second voltage according to the voltage of the primary winding; and a control circuit for generating the control signal for adjustment according to a current detection signal and a reference current signal corresponding to the output current The second voltage; wherein the sum of the first voltage and the second voltage is used as the output voltage. The power conversion device according to claim 1, further comprising a current detection circuit electrically connected to an output terminal of the secondary winding for detecting the current of the output terminal of the secondary winding to generate the current detection Signal to the control circuit. The power conversion device according to claim 1, further comprising a voltage detection circuit electrically connected to an output terminal of the secondary winding for detecting The voltage of the output terminal of the secondary winding is measured to generate a voltage detection signal to the control circuit. The power conversion device according to claim 3, wherein the control circuit includes: a current equalizing circuit for generating a current difference based on the current detection signal and the reference current signal; and a compensator for generating a current difference based on the current The difference and the voltage detection signal generate a compensation signal; and a controller for generating the control signal according to the compensation signal. The power conversion device according to claim 1, further comprising a full bridge circuit, the full bridge circuit comprising: a first switch, a first end of the first switch is electrically connected to a first end of the secondary winding , A second end of the first switch is electrically connected to a first end of the power supply; a second switch, a first end of the second switch is electrically connected to the first end of the power supply, the second switch A second end of the secondary winding is electrically connected to a second end; a third switch, a first end of the third switch is electrically connected to the first end of the secondary winding, and the third switch A second end is electrically connected to the load; and a fourth switch, a first end of the fourth switch is electrically connected to the load, and a second end of the fourth switch is electrically connected to the second end of the secondary winding Two ends. The power conversion device according to claim 5, wherein the control circuit turns on the first switch and the fourth switch, and turns off the second switch and the third switch, so that the second voltage is used as a positive voltage compensation. The power conversion device according to claim 5, wherein the control circuit turns off the first switch and the fourth switch, and turns on the second switch and the third switch, so that the second voltage is used as a negative voltage compensation. The power conversion device according to claim 5, wherein the converter is a bidirectional converter, and the power conversion device further includes a fifth switch, and a first end of the fifth switch is electrically connected to the secondary winding The second end, and a second end of the fifth switch is grounded. The power conversion device according to claim 8, wherein the control circuit turns on the third switch and the fifth switch, and turns off the first switch, the second switch, and the fourth switch, so that the converter automatically The load receives energy to charge the power source. The power conversion device according to claim 1, wherein the converter further comprises: a diode having: an anode terminal electrically connected to the secondary winding; and a cathode terminal electrically connected to the power source; and A capacitor has: a first terminal electrically connected to the cathode terminal; and a second terminal electrically connected to the load. The power conversion device according to claim 1, wherein the converter further comprises: a diode having: an anode terminal electrically connected to the secondary winding; and a cathode terminal electrically connected to the load; and a capacitor , Having: a first end electrically connected to the cathode end; and a second end electrically connected to the power supply. A power supply system includes a plurality of power conversion devices for respectively providing an output voltage and an output current to a load. Each of the power conversion devices includes: a power supply for providing a first voltage; and a conversion The device includes: a switch; and a transformer, including: a primary winding connected in series to the switch to receive the first voltage, wherein the primary winding and the switch are connected in parallel to the power source; and the secondary winding is connected to the power source in series And the load; wherein the switch is used to switch according to a control signal, so that the secondary bypass The group generates a second voltage according to the voltage of the primary winding; and a control circuit for generating the control signal according to a current detection signal and a reference current signal corresponding to the output current, so as to control the switch to adjust the second Voltage, so that the output voltages of the power conversion devices are equal. The power supply system according to claim 12, wherein the reference current signal is an average value of the output currents of the power conversion devices. The power supply system of claim 12 further includes a voltage detection circuit for detecting the voltage of an output terminal of the secondary winding to generate a voltage detection signal to the control circuit. The power supply system according to claim 14, wherein the control circuit generates a current difference value according to the current detection signal and the reference current signal, generates a compensation signal according to the current difference value and the voltage detection signal, and according to The compensation signal generates the control signal. The power supply system according to claim 12, wherein at least one of the power conversion devices includes a full-bridge circuit, the full-bridge circuit includes: a first switch, and a first end of the first switch is coupled A first end of the secondary winding, a second end of the first switch is coupled to a first end of the power supply A second switch, a first end of the second switch is coupled to the first end of the power supply, a second end of the second switch is coupled to a second end of the secondary winding; a third Switch, a first end of the third switch is coupled to the first end of the secondary winding, a second end of the third switch is coupled to the load; and a fourth switch, a first end of the fourth switch One end is coupled to the load, and a second end of the fourth switch is coupled to the second end of the secondary winding. The power supply system according to claim 16, wherein the converter of the at least one of the power conversion devices is a bidirectional converter, and the at least one of the power conversion devices further includes a fifth switch A first end of the fifth switch is electrically connected to the second end of the secondary winding, and a second end of the fifth switch is grounded. The power supply system according to claim 17, wherein the control circuit turns on the third switch and the fifth switch, and turns off the first switch, the second switch, and the fourth switch, so that the converter automatically The load receives energy to charge the power source. The power supply system according to claim 12, further comprising a power supply module for receiving the reference current signal and outputting a third current to the load, wherein the reference current signal is the power supplies The average value of the output currents of the conversion device and the third current.

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