A parallel current-sharing circuit for distributed power supply system

Abstract

The present invention discloses a distributed power system parallel current balancing circuit in the field of distributed power system parallel connection, including N automatic current balancing circuits connected one-to-one with N parallel module power supplies, the automatic current balancing circuit including a detection unit for detecting a signal proportional to the output current of the module power supply and converting it into a voltage signal proportional to the output current; a comparison unit for comparing the voltage signal detected by its own detection unit with the voltage signal of the main module; and an adjustment unit for receiving the output result of the comparison unit and adjusting the output voltage of its own module power supply according to the output result. The present invention can correct and balance the load current of each power module used in parallel in the distributed power system, has a small load dynamic response, a small current balancing accuracy, which can be controlled within 1%, a small current distribution error in the entire load range, can achieve redundancy, and prevent a large current from being fed back to the power supply when a power failure occurs in the parallel system, thereby protecting the power supply system.

Description

Technical Field

[0001] The invention relates to the field of parallel connection of distributed power supply systems, and in particular to a parallel current sharing circuit of a distributed power supply system. Background Art

[0002] In the fields of aerospace, aviation, shipbuilding, weapons, communications, etc. where switching power supplies are widely used, it is an effective way to connect multiple small and medium power modules in parallel to jointly bear high-power output and form a distributed power system. Compared with the traditional centralized power supply system, it can meet the high-power requirements of the load by changing the number of parallel modules without redesigning the power supply system. The parallel operation of power supplies is an effective way to modularize and increase the power of power products. In order to achieve the purpose and effect of output voltage, output current, and output power expansion, the problem of current sharing after the power modules are connected in parallel must be solved. Different solutions have a great impact on the stability and reliability of the entire power expansion system. Since the module output voltages of each parallel unit are not exactly the same and the output impedance is not consistent, if they are directly connected in parallel, they will bear unbalanced loads, resulting in some power modules shortening their life due to large output currents, or even failures due to overcurrent. Therefore, current sharing measures must be taken to balance the output currents of each parallel power module.

[0003] A complete parallel current-sharing circuit for a distributed power supply system should meet the following three conditions: when the input voltage or load changes, the output voltage of each parallel power supply remains stable and has good load transient response characteristics; the output current borne by each parallel power supply is evenly distributed; and current balancing is combined with redundancy technology.

[0004] At present, the commonly used current sharing methods for parallel connection of power modules are: output impedance method, designated master-slave method, average current automatic current sharing method, thermal stress automatic current sharing method, automatic master-slave method, etc.

[0005] The output impedance method is difficult to achieve current sharing for parallel modules with different rated powers.

[0006] The biggest problem with the designated master-slave method is the irreplaceability of the master module. If it fails, the entire system will be completely paralyzed. It is not suitable for redundant parallel systems. At the same time, any change in error voltage caused by non-load current will cause the current of each parallel power module to be redistributed, thereby reducing the current sharing accuracy and being susceptible to external noise interference.

[0007] The average current automatic current balancing method can accurately achieve current balancing. One of its disadvantages is that when the current balancing bus is short-circuited or when any module connected to the bus fails to work, the bus voltage drops, causing the voltage of each module to decrease, even to its lower limit, causing power system failure.

[0008] The problem with the thermal stress automatic current equalization method is that due to the different positions of the modules in the power supply system, the external conditions such as convection and heat dissipation are different, and the temperature is different. The relationship between the temperature change and the current of each module cannot be accurately matched, so it is seldom used.

[0009] The automatic master-slave method is that among n parallel power modules, the power module with the largest output current is automatically determined as the master module, and the remaining power modules are slave modules. Its current balancing accuracy is generally within 5%, which meets the national standard requirements, has good load dynamic response, can achieve redundancy and other technical characteristics, and is widely used. However, in general, the current distribution error is large when working under lighter loads. The present invention belongs to a current balancing circuit, which aims to improve the above technical problems. Summary of the invention

[0010] The object of the present invention is to provide a parallel current sharing circuit for a distributed power supply system to solve the problems raised in the above background technology.

[0011] To achieve the above object, the present invention provides the following technical solutions:

[0012] A parallel current balancing circuit for a distributed power supply system includes N automatic current balancing circuits connected one-to-one with N parallel module power supplies, and the automatic current balancing circuit includes:

[0013] A detection unit for detecting a signal proportional to the output current of a module power supply and converting it into a voltage signal proportional to the output current, wherein the module power supply with the largest voltage signal among the N module power supplies is a master module, and the rest are slave modules, the master module and the slave modules are connected through a current sharing bus, and a diode V3 is connected between the detection unit of each module power supply and the current sharing bus, the cathode of the diode V3 is connected to the current sharing bus, and the anode is connected to the detection unit;

[0014] A comparison unit for comparing a voltage signal detected by the self-detection unit with a voltage signal of a main module;

[0015] An adjustment unit is used to receive the output result of the comparison unit and adjust the output voltage of its own module power supply according to the output result.

[0016] As an improved solution of the present invention, a redundant protection circuit is connected between the automatic current balancing circuit and the output load terminal LOAD(+) of the module power supply, and the redundant protection circuit includes a field effect transistor, and a driving control unit for sampling the on-resistance inside the field effect transistor, comparing the sampling signal with the reference signal and generating a logic level, and driving the field effect transistor on and off through the logic level.

[0017] As an improved solution of the present invention, in the redundant protection circuit, the drive control unit N1 is respectively connected to one end of the resistors RUV, ROV, RRSET, RVDD and the capacitors CA, CBYP, CFLTR, and CVDD, the other ends of the resistors RUV, ROV, and RRSET are simultaneously connected to the ground, the other end of the resistor RVDD is connected to the second power supply circuit, the other ends of the capacitors CBYP and CFLTR are connected to the source of the field effect transistor V5, the source of the field effect transistor V5 is connected to the automatic current equalization circuit, the other ends of the capacitors CA and CVDD are connected to the ground, the gate and drain of the field effect transistor V5 are both connected to the drive control unit N1, and the drain of the field effect transistor V5 is connected to the output load terminal LOAD(+) of the module power supply.

[0018] As an improved solution of the present invention, the detection unit includes a resistor R0, amplifiers A1, A2, A6 and a diode V3. The resistor R0 is connected in series to the main power output voltage terminal +OUT of the module power supply. The two input terminals of the amplifier A1 are respectively connected in parallel with the resistor R0 through resistors R11 and R12. The output terminal of the amplifier A1 is connected to the ground through a capacitor C2 and a resistor R13 connected in parallel, and the other is connected to the in-phase input terminal of the amplifier A2; the inverting input terminal of the amplifier A2 is connected to the output terminal, and the output terminal is connected to the in-phase input terminal of the amplifier A6 through the resistor R1, and the other is connected to the in-phase input terminal of the amplifier A6. The inverting input terminal of the amplifier A6 is connected to the SHARE end of the current sharing bus through the resistor R8 in one way, and is grounded in the other way through the resistor R7; the R7 is also connected to one end of the undervoltage protection voltage and bias circuit in parallel, and the other end of the undervoltage protection circuit and the bias circuit is connected to the first power supply circuit through the resistor R10 in one way, and is connected to the cathode of the Zener diode V1 in the other way. The anode of the Zener diode V1 is grounded, and the two ends of the Zener diode V1 are connected in parallel with a capacitor C1; the output end of the amplifier A6 is connected to the anode of the diode V3, and the cathode of the diode V3 is connected to the SHARE end of the current sharing bus.

[0019] As an improved solution of the present invention, the comparison unit includes amplifiers A3 and A4, wherein the in-phase input terminal of the amplifier A3 is connected to the SHARE end of the current sharing bus through a resistor R4, and is grounded through a resistor R3 in another way; the inverting input terminal of the amplifier A3 is grounded through a resistor R5 in one way, and is connected to its own output terminal and the in-phase input terminal of the amplifier A4 through a resistor R6 in another way; the inverting input terminal of the amplifier A4 is connected to the inverting input terminal of the amplifier A2, and its output terminal is divided into three paths, the first path is connected to the adjustment unit, the second path is connected to the cathode of the Zener diode V2, the anode of the Zener diode V2 is grounded, and the third path is connected in series with a capacitor C5 and a resistor R14 and then grounded.

[0020] As an improved solution of the present invention, the adjustment unit includes an amplifier A5, a transistor V4 and a resistor R9, the in-phase input end of the amplifier A5 is connected to the output end of the amplifier A4, the inverting input end is grounded after passing through the resistor R9, and the other end is connected to the emitter of the transistor V4, the base of the transistor V4 is connected to the output end of the amplifier A5, the collector is connected to the output positive sensing end +OUT_SENSE of the module power supply, and the other end is connected to the output load end LOAD(+) of the module power supply through the resistor R15.

[0021] Beneficial effects: The circuit structure of the present invention is simple, the volume is small, and the integration is high. It can correct and balance the load current of each power module used in parallel in the distributed power supply system within the entire load range, and prevent the large current from being fed back to the power supply when a power failure occurs in the parallel system, thereby protecting the power supply system. The present invention has important use value in realizing high-power power supply systems and improving reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a principle block diagram of the present invention;

[0023] Figure 2 For the present invention Figure 1 Circuit diagram of redundant protection circuit;

[0024] Figure 3 For the present invention Figure 1 Circuit diagram of the automatic current equalizing circuit. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Example 1, see Figure 1 A parallel current balancing circuit for a distributed power supply system includes N automatic current balancing circuits connected one-to-one with N parallel module power supplies, the automatic current balancing circuit is respectively connected to the main power output voltage terminal +OUT, the output positive induction terminal +OUT_SENSE and the output load terminal LOAD(+) of the module power supply, and is also connected to a first power supply circuit and an output ground, and the first power supply circuit provides a working voltage for the automatic current balancing circuit.

[0027] The automatic current sharing circuit includes a detection unit for detecting a signal proportional to the output current of the module power supply and converting it into a voltage signal proportional to the output current, wherein the module power supply with the largest voltage signal among the N module power supplies is a master module, and the rest are slave modules, the master module and the slave modules are connected through a current sharing bus, and a diode V3 is connected between the detection unit of each module power supply and the current sharing bus, the cathode of the diode V3 is connected to the current sharing bus, and the anode is connected to the detection unit;

[0028] A comparison unit for comparing a voltage signal detected by the self-detection unit with a voltage signal of a main module;

[0029] An adjustment unit is used to receive the output result of the comparison unit and adjust the output voltage of its own module power supply according to the output result.

[0030] The specific implementation steps of this embodiment include:

[0031] S1: The detection unit detects a signal proportional to the output current of the module power supply and converts it into a voltage signal proportional to the output current. The module power supply with the largest voltage signal, that is, the largest output current, among the N module power supplies is determined as the master module, and the remaining module power supplies are determined as slave modules;

[0032] S2: The voltage signal of the master module determines the current-sharing bus voltage proportional to its output current. The slave module uses the current-sharing bus voltage as a reference and reads the current-sharing bus voltage through the comparison unit, and compares it with the voltage signal of its own module power supply to output an error signal.

[0033] S3: The adjustment unit of the slave module receives the error signal, adjusts the output voltage of its own module power supply according to the error signal, realizes current sharing between the master module and the slave module, and achieves the purpose of load balancing for each module.

[0034] In this embodiment, the slave module operates as a current-controlled current source.

[0035] In this embodiment, the determination of the master module and the slave module and the adjustment of the output voltage of the slave module are not affected by the load, that is, when there is no load, light load or heavy load, the above steps are used to achieve the current distribution between the module power supplies. Since each module power supply can adjust itself based on the actual current sharing bus voltage, the current distribution is precise and reasonable, and the current sharing accuracy can be controlled within 1%, which can make the current distribution error in the entire load range (including light load) reach a smaller level.

[0036] In Example 2, a redundant protection circuit is connected between the automatic current balancing circuit and the output load terminal LOAD (+) of the module power supply. The redundant protection circuit is respectively connected to the second power supply circuit and the output ground, and provides an operating voltage through the second power supply circuit. The redundant protection circuit includes a field effect transistor, and a driving control unit for sampling the on-resistance inside the field effect transistor, comparing the sampling signal with a reference signal and generating a logic level, and driving the field effect transistor on and off through the logic level.

[0037] The function of the redundant protection circuit is that when a module power supply fails in the distributed power supply system, the drive control unit in the redundant protection circuit connected to the module power supply controls the field effect tube to shut down by sampling the on-resistance of the field effect tube to prevent the current from being fed back to the unobstructed power supply, thereby playing a protective role and avoiding the operation of the entire power supply system being affected by the failure of a module power supply.

[0038] Further, see Figure 2 One implementation of the redundant protection circuit is that the drive control unit N1 is respectively connected to one end of the resistors RUV, ROV, RRSET, RVDD and the capacitors CA, CBYP, CFLTR, and CVDD, the other ends of the resistors RUV, ROV, and RRSET are simultaneously connected to the ground, the other end of the resistor RVDD is connected to the second power supply circuit, the other ends of the capacitors CBYP and CFLTR are connected to the source of the field effect transistor V5, the source of the field effect transistor V5 is connected to the automatic current balancing circuit, the other ends of the capacitors CA and CVDD are connected to the ground, the gate and drain of the field effect transistor V5 are both connected to the drive control unit N1, and the drain of the field effect transistor V5 is connected to the output load terminal LOAD(+) of the module power supply.

[0039] The driving control unit N1 mainly includes a field effect tube driver, a resistor RUV is an undervoltage protection point voltage setting resistor, a resistor ROV is an overvoltage protection point voltage setting resistor, a resistor RRSET is a reset resistor, a resistor RVDD is a pull-up resistor for the power supply voltage of the driving control unit N1, and capacitors CA, CBYP, CFLTR, and CVDD are all filter capacitors.

[0040] The current detection unit inside the drive control unit N1 samples and amplifies the on-resistance of the field effect tube V5 itself. The comparator inside the drive control unit N1 compares and processes the sampling signal with the reference voltage, generates a driving level with a corresponding logical relationship to the gate of the field effect tube V5, controls the field effect tube V5 to be turned on or off, and turns off the field effect tube V5 when a short circuit or other fault occurs in a power supply in the system, preventing the current from being fed back to the fault-free power supply, thereby protecting the power supply system.

[0041] Example 3, see Figure 3One implementation of the automatic current balancing circuit is that the detection unit includes a resistor R0, amplifiers A1, A2, A6 and a diode V3. The resistor R0 is connected in series to the main power output voltage terminal +OUT of the module power supply. The two input terminals of the amplifier A1 are connected in parallel with the resistor R0 through resistors R11 and R12 respectively. One output terminal of the amplifier A1 is grounded through a capacitor C2 and a resistor R13 connected in parallel, and the other output terminal of the amplifier A1 is connected to the same phase input terminal of the amplifier A2.

[0042] The inverting input terminal of the amplifier A2 is connected to the output terminal, and the output terminal is connected to the non-inverting input terminal of the amplifier A6 through the resistor R1 in one way and connected to the resistor R2 in the other way and then grounded.

[0043] The inverting input terminal of the amplifier A6 is connected to the SHARE end of the current sharing bus through a resistor R8 in one way, and is grounded in the other way through a resistor R7; R7 is also connected to one end of the undervoltage protection voltage and bias circuit in parallel, and the other end of the undervoltage protection circuit and the bias circuit is connected to the first power supply circuit through a resistor R10 in one way, and is connected to the cathode of the Zener diode V1 in the other way. The anode of the Zener diode V1 is grounded, and a capacitor C1 is connected in parallel at both ends of the Zener diode V1; the output terminal of the amplifier A6 is connected to the anode of the diode V3, and the cathode of the diode V3 is connected to the SHARE end of the current sharing bus.

[0044] Resistor R0 detects a signal proportional to the output current of the module power supply at the output end +OUT of the module power supply, and sends it to amplifier A1. The output of amplifier A1 is proportional to the output current of the module power supply. Amplifier A2 acts as a follower, and its main function is to isolate the signal. Its output follows the output of the current detection amplifier A1, and is supplied to the in-phase input end of amplifier A6 as an input signal. The gain of amplifier A6 is 1, so the output voltage of amplifier A6 is equal to that of amplifier A1. When the output voltage is the highest relative to the potential of all module power supplies, the power supply module is called the master module. The output of amplifier A6 of the master module determines the current sharing bus voltage, and other module power supplies become slave modules. Due to the effect of diode V3 connected in series at the output end of amplifier A6, the output of amplifier A6 of the slave module is not connected to the current sharing bus.

[0045] The voltage regulator V1 stabilizes the working voltage of the automatic current equalization circuit 1. Resistors R1, R2, R7, R8, R11, and R12 are all current limiting resistors. Resistor R10 is a pull-up resistor connected to the first power supply circuit. The function of resistor R13 is to adjust the gain of amplifier A1. Capacitors C3 and C4 are respectively connected to the two input terminals of amplifier A1, and the other ends of capacitors C3 and C4 are grounded. Capacitors C1, C2, C3, and C4 are filter capacitors, all used to remove signal noise.

[0046] The comparison unit includes amplifiers A3 and A4. The in-phase input terminal of amplifier A3 is connected to the current sharing bus SHARE terminal through resistor R4 and is grounded through resistor R3. The inverting input terminal of amplifier A3 is grounded through resistor R5 and is connected to its own output terminal and the in-phase input terminal of amplifier A4 through resistor R6.

[0047] The inverting input terminal of amplifier A4 is connected to the inverting input terminal of amplifier A2, and its output terminal is divided into three paths. The first path is connected to the adjustment unit, the second path is connected to the cathode of the Zener diode V2, the anode of the Zener diode V2 is grounded, and the third path is connected in series with capacitor C5 and resistor R14 and then grounded.

[0048] The adjustment unit includes an amplifier A5, a transistor V4 and a resistor R9. The in-phase input terminal of the amplifier A5 is connected to the output terminal of the amplifier A4, the inverting input terminal is grounded after passing through the resistor R9, and the other terminal is connected to the emitter of the transistor V4. The base of the transistor V4 is connected to the output terminal of the amplifier A5, the collector terminal is connected to the output positive sensing terminal +OUT_SENSE of the module power supply, and the other terminal is connected to the output load terminal LOAD(+) of the module power supply through the resistor R15.

[0049] Amplifier A3 reads the current-sharing bus voltage, transmits the signal of the current-sharing bus voltage to the in-phase input terminal of amplifier A4, and compares it with the output voltage of amplifier A1. The error voltage output by amplifier A4 is output to amplifier A5, which is used to adjust the output voltage of the module power supply to balance the load current of all parallel module power supplies.

[0050] Specifically, the output voltage of amplifier A4 in the stable state is a function of the output voltage difference between amplifier A1 and amplifier A3, and the voltage difference is zero when working in the master module state. To ensure the correct output state of amplifier A4, a bias voltage of tens of millivolts is connected in series at the inverting input terminal of A4 to increase the conversion margin between the master and slave module power supplies. At the same time, it is ensured that the output of amplifier A4 working in the master module state is zero, but all slave modules generate non-zero error voltages, which are proportional to the difference between the output of amplifier A1 of each module power supply and the bus voltage. The error voltage is used to adjust the output voltage of the module power supply to balance the load current of all parallel module power supplies, which is mainly achieved by amplifier A5 and transistor V4. Amplifier A5 drives the on and off of transistor V4 according to the error signal, and adjusts the output voltage of the module power supply by changing the voltage on resistor R9 through the error signal, thereby achieving current sharing between the module power supplies.

[0051] The voltage regulator V2 is used to stabilize the output voltage of the amplifier A4. The resistors R3, R4, R5 and R6 are all current limiting resistors. The resistor R14 and the capacitor C5 form a compensation network connected between the amplifier A4 and the ground wire to increase the phase margin of the load current sharing loop. The resistor R15 is the induction resistor between the module power supply positive sensing terminal +OUT_SENSE and the output positive load terminal LOAD(+).

[0052] The present invention adopts a simple circuit structure to achieve the purpose of load balancing of various DC / DC module power supplies used in parallel in the power supply system, with high current balancing accuracy and comprehensive design considerations for various functional units, thus providing a guarantee for improving the stability, safety and reliability of the power supply system.

[0053] Although this specification is described according to implementation modes, not every implementation mode includes only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0054] In the description of the present invention, it should be noted that relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0055] In the description of the present invention, it is also necessary to explain that the orientations or positional relationships indicated by the terms "upper", "lower", "inside", "outside", etc. are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is usually placed when used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0056] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0057] Therefore, the above description is only a preferred embodiment of the present application and is not intended to limit the scope of implementation of the present application; that is, all equivalent changes made according to the scope of the claims of the present application are within the protection scope of the claims of the present application.

Claims

1. A parallel current sharing circuit for a distributed power system, characterized in that: The invention comprises N automatic current balancing circuits connected one-to-one with N parallel module power supplies, wherein the automatic current balancing circuits comprise: A detection unit for detecting a signal proportional to the output current of a module power supply and converting it into a voltage signal proportional to the output current, wherein the module power supply with the largest voltage signal among the N module power supplies is a master module, and the rest are slave modules, the master module and the slave modules are connected through a current sharing bus, and a diode V3 is connected between the detection unit of each module power supply and the current sharing bus, the cathode of the diode V3 is connected to the current sharing bus, and the anode is connected to the detection unit; A comparison unit for comparing a voltage signal detected by the self-detection unit with a voltage signal of a main module; An adjustment unit for receiving an output result of the comparison unit and adjusting the output voltage of its own module power supply according to the output result; The detection unit includes a resistor R0, amplifiers A1, A2, A6 and a diode V3, wherein the resistor R0 is connected in series to the main power output voltage terminal +OUT of the module power supply, and the two input terminals of the amplifier A1 are connected in parallel with the resistor R0 through resistors R11 and R12 respectively, and the output terminal of the amplifier A1 is connected to the ground through a capacitor C2 and a resistor R13 connected in parallel, and the other terminal is connected to the in-phase input terminal of the amplifier A2; the inverting input terminal of the amplifier A2 is connected to the output terminal, and the output terminal is connected to the in-phase input terminal of the amplifier A6 through the resistor R1, and the other terminal is connected to the resistor R2 and then grounded; The inverting input end of the amplifier A6 is connected to the SHARE end of the current sharing bus through a resistor R8, and is grounded through a resistor R7; the resistor R7 is also connected to one end of the undervoltage protection voltage and bias circuit in parallel, and the other end of the undervoltage protection circuit and the bias circuit is connected to the first power supply circuit through a resistor R10, and is connected to the cathode of the voltage zener diode V1 in another way, the anode of the voltage zener diode V1 is grounded, and the two ends of the voltage zener diode V1 are connected in parallel with a capacitor C1; the output end of the amplifier A6 is connected to the anode of the diode V3, and the cathode of the diode V3 is connected to the SHARE end of the current sharing bus; The comparison unit includes amplifiers A3 and A4, wherein the in-phase input terminal of the amplifier A3 is connected to the SHARE terminal of the current sharing busbar through a resistor R4, and is grounded through a resistor R3 in another way; the inverting input terminal of the amplifier A3 is grounded through a resistor R5 in one way, and is connected to its own output terminal and the in-phase input terminal of the amplifier A4 in another way through a resistor R6; the inverting input terminal of the amplifier A4 is connected to the inverting input terminal of the amplifier A2, and its output terminal is divided into three ways, the first way is connected to the adjustment unit, the second way is connected to the cathode of the voltage zener diode V2, the anode of the voltage zener diode V2 is grounded, and the third way is connected in series with a capacitor C5 and a resistor R14 in sequence and then grounded; The adjustment unit includes an amplifier A5, a transistor V4 and a resistor R9. The in-phase input end of the amplifier A5 is connected to the output end of the amplifier A4, the inverting input end is grounded after passing through the resistor R9, and the other end is connected to the emitter of the transistor V4. The base of the transistor V4 is connected to the output end of the amplifier A5, the collector is connected to the output positive sensing end +OUT_SENSE of the module power supply, and the other end is connected to the output load end LOAD(+) of the module power supply through the resistor R15.

2. A distributed power system parallel current sharing circuit according to claim 1, characterized in that: A redundant protection circuit is connected between the automatic current balancing circuit and the output load terminal LOAD(+) of the module power supply. The redundant protection circuit includes a field effect tube and a driving control unit for sampling the on-resistance inside the field effect tube, comparing the sampling signal with the reference signal and generating a logic level, and driving the field effect tube on and off through the logic level.

3. A distributed power system parallel current sharing circuit according to claim 2, characterized in that: In the redundant protection circuit, the drive control unit N1 is respectively connected to one end of the resistors RUV, ROV, RRSET, RVDD and the capacitors CA, CBYP, CFLTR, and CVDD, the other ends of the resistors RUV, ROV, and RRSET are simultaneously connected to the ground, the other end of the resistor RVDD is connected to the second power supply circuit, the other ends of the capacitors CBYP and CFLTR are connected to the source of the field effect transistor V5, the source of the field effect transistor V5 is connected to the automatic current balancing circuit, the other ends of the capacitors CA and CVDD are connected to the ground, the gate and drain of the field effect transistor V5 are both connected to the drive control unit N1, and the drain of the field effect transistor V5 is connected to the output load terminal LOAD(+) of the module power supply.

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