Silicon carbide MOSFET parallel current sharing system and method for pulse power supply

Abstract

The invention discloses a silicon carbide MOSFET parallel current sharing system and method for a pulse power supply, and belongs to the technical field of SiC MOSFET parallel current sharing, the system comprises a main power circuit connected with a plurality of SiC MOSFETs in parallel and an active driving circuit, when the SiC MOSFETs are turned on, a source inductor generates an induced voltage in direct proportion to the current rising rate, and when the SiC MOSFETs are turned on, the active driving circuit drives the main power circuit to rotate; current sharing when a plurality of SiC MOSFETs are connected in parallel is realized through an in-phase amplification circuit used for detecting and amplifying an induced voltage, a differential amplification circuit used for detecting and comparing an induced voltage value, and a proportional current source circuit is controlled to extract a SiC MOSFET gate drive current. By adopting the method, the unbalanced current can be suppressed, the balance of the current flowing through each branch of the parallel SiC MOSFETs is ensured, the SiC MOSFET device in the high-voltage pulse power supply is effectively protected, and the working reliability of the circuit is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to SiC MOSFET parallel current sharing technical field, especially to a kind of silicon carbide MOSFET parallel current sharing system and method for pulse power supply. BACKGROUND

[0002] With the development of power electronics technology, wide bandgap power semiconductor devices are widely used in high frequency, high temperature and high power power electronics fields, and SiC MOSFETT (silicon carbide metal oxide semiconductor field effect transistor) is often used instead of traditional non-solid-state switch in all-solid-state high-voltage pulse power supply field. When high-voltage pulse power supply forms pulse output, the current flowing through SiC MOSFET device is large, but the current level of commercial mass production SiC MOSFET is low, so multiple SiC MOSFET discrete devices need to be connected in parallel to improve the current level of the entire circuit in power pulse output occasions. However, due to the difference in parasitic parameters of parallel discrete branches and the immaturity of SiC MOSFET device preparation process, the on-resistance, threshold voltage, parasitic inductance and parasitic capacitance of SiC MOSFET device will have certain differences, which inevitably causes dynamic and static current imbalance problems of SiC MOSFET device in parallel operation. Unbalanced current will cause uneven loss between parallel devices, which is easy to produce higher current overshoot on the weakest device, endangering the safe operation of other parallel devices, and thus affecting the working reliability of the entire pulse circuit system.

[0003] To solve the problem of current imbalance caused by SiC MOSFET parallel application, in order to reduce the current imbalance degree of SiC MOSFET parallel, many scholars propose to add coupling inductance, that is, to increase the coupling inductance in the circuit to reduce the current imbalance degree of SiC MOSFET parallel. However, the added coupling inductance will increase with the increase of power, and the volume of the coupling inductance itself will also increase. Moreover, the parasitic parameters caused by coupling inductance may exacerbate high-frequency switching transient oscillation at high frequency, which affects the output pulse waveform of high-voltage pulse power supply and reduces the electromagnetic compatibility of the entire system. SUMMARY

[0004] The purpose of the present application is to provide a kind of silicon carbide MOSFET parallel current sharing system and method for pulse power supply, which reduces the imbalance degree of parallel SiC MOSFET current, protects each SiC MOSFET device in parallel, and improves the working reliability of the entire high-voltage pulse power supply system.

[0005] To achieve the above purpose, the present application provides a kind of silicon carbide MOSFET parallel current sharing system for pulse power supply, comprising main power circuit and active drive circuit connected in parallel with multiple SiC MOSFET.

[0006] The inductance at the source of the plurality of SiC MOSFETs generates an induced voltage proportional to the current rise rate when the plurality of SiC MOSFETs are turned on in parallel;

[0007] The active drive circuit includes a non-inverting amplification circuit for detecting and amplifying the induced voltage, a differential amplification circuit for detecting and comparing the induced voltage values, and a proportional current source circuit for extracting the gate current of the SiC MOSFET, and by detecting the induced voltage, amplifying the induced voltage, comparing the induced voltage, and extracting the gate current, the current balance of the plurality of SiC MOSFETs in parallel is realized.

[0008] Preferably, the main power circuit has two SiC MOSFETs in parallel, the two SiC MOSFETs are SiC MOSFET M1 and SiC MOSFET M2 respectively, and the main power circuit further includes a first DC power supply V dc , a DC bus capacitor C dc , a load inductor L d , a diode D3, the sources of the two SiC MOSFETs are connected to each other and grounded after being connected to each other at one end of the DC bus capacitor C dc , the negative electrode of the first DC power supply V dc , the gates of the two SiC MOSFETs are connected to each other after being connected in series with a resistor, and the positive electrode of the drive signal source V gs , the drains of the two SiC MOSFETs are connected to each other and connected to the anode of the diode D3 and one end of the load inductor L d , the other end of the load inductor L d , the positive electrode of the first DC power supply V dc , and the cathode of the diode D3 are connected to each other at the other end of the DC bus capacitor C dc ; the source of the SiC MOSFET M1 is connected in series with one end of the inductor L1, and the voltage at the source of the SiC MOSFET M1, the non-inverting input terminal of U1 in the first non-inverting amplification circuit, one end of R5 in the first differential amplification circuit, and one end of R 12 in the second differential amplification circuit are equal; the source of the SiC MOSFET M2 is connected in series with one end of the inductor L2, and the voltage at the source of the SiC MOSFET M2, the non-inverting input terminal of U3 in the second non-inverting amplification circuit, one end of R3 in the first differential amplification circuit, and one end of R 14 in the second differential amplification circuit are equal.

[0009] Preferably, the active drive circuit includes a conventional drive circuit, and the conventional drive circuit includes a drive signal source V gs , a resistor R g1 , a resistor Rg2 The positive pole of the drive signal source V gs The one end of the resistance R g1 The one end of the resistance R g2 The negative pole of the drive signal source V gs The other end of the inductor L1, the other end of the inductor L2, the negative pole of the first direct current source V dc The one end of the direct bus capacitor C dc The one end of the direct bus capacitor C gs The drive signal source V L1 The inductor L1 generates an induced voltage V L2 .

[0010] Preferably, the same-phase amplification circuit comprises a first same-phase amplification circuit and a second same-phase amplification circuit, the first same-phase amplification circuit is composed of an operational amplifier U1, a resistance R1, and a resistance R2, the one end of the resistance R1 is grounded, the other end of the resistance R1, the one end of the resistance R2, and the inverting input terminal of the operational amplifier U1 are connected with each other; the second same-phase amplification circuit is composed of an operational amplifier U3, a resistance R 10 , and a resistance R 11 , the one end of the resistance R 11 is grounded, the other end of the resistance R 11 , the one end of the resistance R 10 , and the inverting input terminal of the operational amplifier U3 are connected with each other; the differential amplification circuit comprises a first differential amplification circuit and a second differential amplification circuit, the first differential amplification circuit is composed of an operational amplifier U2, a resistance R3, a resistance R4, a resistance R5, and a resistance R6, the one end of the resistance R3, the one end of the resistance R4, and the inverting input terminal of the operational amplifier U2 are connected with each other, the one end of the resistance R6 is grounded, the one end of the resistance R5, the other end of the resistance R6, and the non-inverting input terminal of the operational amplifier U2 are connected with each other; the second differential amplification circuit is composed of an operational amplifier U4, a resistance R 12 , a resistance R 13 , a resistance R 14 , and a resistance R 15 , the one end of the resistance R 12 , the one end of the resistance R 13 , and the inverting input terminal of the operational amplifier U4 are connected with each other, the one end of the resistance R 15 is grounded, the one end of the resistance R 14 , the other end of the resistance R 15 , and the non-inverting input terminal of the operational amplifier U4 are connected with each other; the same-phase input terminal of the operational amplifier U1 in the first same-phase amplification circuit, the same-phase input terminal of the operational amplifier U2 in the first differential amplification circuit, and the induced voltage value of the source electrode of the SiC MOSFET M1 are equal and are VL1 The in-phase input end of the operational amplifier U3 in the second in-phase amplification circuit, the in-phase input end of the operational amplifier U4 in the second differential amplification circuit, and the induced voltage value of the source of the SiC MOSFET M2 are equal and are V L2 The V L1 is calculated by the following formula: The V L2 is calculated by the following formula: L1 is the inductance in series with the source of the SiC MOSFET M1 in the main power circuit, L2 is the inductance in series with the source of the SiC MOSFET M2 in the main power circuit, di1 / dt represents the current change rate per unit time through the SiC MOSFET M1, and di2 / dt represents the current change rate per unit time through the SiC MOSFET M2.

[0011] Preferably, the proportional current source circuit includes a first proportional current source circuit and a second proportional current source circuit. The first proportional current source circuit includes an NPN transistor Q1, an NPN transistor Q2, an NPN transistor Q3, a resistor R7, a resistor R8, a resistor R9, a diode D1, a second DC power supply V CC The base of the NPN transistor Q1 is the input end of the first proportional current source circuit, and the anode of the diode D1 is the output end of the first proportional current source circuit. The collector of the NPN transistor Q1 is connected to the power supply V CC The emitter of the NPN transistor Q1 is connected to one end of the resistor R7, and the other end of the resistor R7, the collector of the NPN transistor Q2, the base of the NPN transistor Q2, and the base of the NPN transistor Q3 are connected to each other. The emitter of the NPN transistor Q2 is connected to one end of the resistor R8, the collector of the NPN transistor Q3 is connected to the cathode of the diode D1, the emitter of the NPN transistor Q3 is connected to one end of the resistor R9, and the other end of the resistor R8 and the other end of the resistor R9 are connected to each other and grounded. The anode of the diode D1, the gate of the SiC MOSFET M1, and the other end of the resistor R g1 The second proportional current source circuit includes an NPN transistor Q4, an NPN transistor Q5, an NPN transistor Q6, a resistor R 16 , a resistor R 17 , a resistor R 18 , a diode D2, and a power supply Vcc. The base of the NPN transistor Q4 is the input end of the second proportional current source circuit, and the anode of the diode D2 is the output end of the second proportional current source circuit. The collector of the NPN transistor Q4 is connected to the power supply V CC The emitter of the NPN transistor Q4 is connected to one end of the resistor R 16 , and the other end of the resistor R16 The other end of the resistor R 17 , the anode of the diode D2, the gate of the SiC MOSFET M2 and the other end of the resistor R 18 are connected with each other, and the other end of the resistor R 17 is grounded. 18 The other end of the resistor R g2 is connected with the other end of the resistor R

[0012] Preferably, a method for parallel current sharing system of SiC MOSFET for pulse power supply comprises the following steps:

[0013] Step 1: Working process A is the initial current sharing state when two SiC MOSFETs are turned on, when the SiC MOSFET M1 and the SiC MOSFET M2 are turned on, the inductor L1 connected in series with the source of the SiC MOSFET M1 generates an induced voltage V L1 , the inductor L2 connected in series with the source of the SiC MOSFET M2 generates an induced voltage V L2 , the detected induced voltage V L1 is amplified through a first same-phase amplification circuit and then a current is extracted from the branch of the gate of the SiC MOSFET M1 through a first proportional current source circuit; the detected induced voltage V L2 is amplified through a second same-phase amplification circuit and then a current is extracted from the branch of the gate of the SiC MOSFET M2 through a second proportional current source circuit.

[0014] Step 2: under the condition of working process A, the amplified induced voltage is compared through a differential amplification circuit, when V L1 is greater than V L2 , working process B is entered, at this time, the first differential amplification circuit acts on the first proportional current source circuit and controls the triode Q1 in the first proportional current source circuit to be turned on, and then a current is extracted from the gate branch of the SiC MOSFET M1 for current sharing; when VL1 is less than VL2, working process C is entered, at this time, the second differential amplification circuit acts on the second proportional current source circuit and controls the triode Q4 in the second proportional current source circuit to be turned on, and then a current is extracted from the gate branch of the SiC MOSFET M2 for current sharing.

[0015] Therefore, the SiC MOSFET parallel current sharing system and method for pulse power supply have the beneficial effects that:

[0016] 1) By designing an active drive circuit, the present invention effectively improves the problem of parallel current imbalance in SiC MOSFETs caused by differences in parasitic parameters of parallel discrete branches, immature SiC MOSFET device manufacturing processes, and certain differences in parameters such as on-resistance, threshold voltage, parasitic inductance, and parasitic capacitance. This reduces current imbalance and improves the reliability of the entire high-voltage pulse system.

[0017] 2) Compared with the existing commonly used series coupled inductor method, the present invention effectively reduces the imbalance of the parallel current of SiC MOSFET while reducing other problems such as system volume increase, pulse output waveform distortion and other electromagnetic interference caused by coupled inductors, thereby further improving the service life and reliability of the high-voltage pulse power supply.

[0018] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a circuit diagram of a parallel current-sharing system of silicon carbide MOSFETs for a pulse power supply of the present invention.

[0020] Figure 2 A circuit diagram of the working process A of the present invention;

[0021] Figure 3 A circuit diagram of working process B of the present invention;

[0022] Figure 4 A circuit diagram of working process C of the present invention;

[0023] Figure 5 3 is a schematic diagram comparing the current balancing of the present invention with the active drive circuit SiC MOSFET during the turn-on phase. DETAILED DESCRIPTION

[0024] In order to make the purposes, technical solutions and advantages disclosed in the embodiments of the present invention clearer, the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention and are not intended to limit the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, where the same or similar numbers throughout represent the same or similar elements or elements with the same or similar functions.

[0025] It should be noted that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or server that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products or devices.

[0026] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0027] The embodiment of the present invention provides a parallel current sharing system and method for silicon carbide MOSFETs for pulse power supply, wherein the main power circuit is composed of n SiC MOSFETs (Mn, Mn -1 , ..., M1, n ≥ 2) are connected in parallel, each SiC MOSFET source branch is connected in series with an inductor, each SiC MOSFET gate branch is connected in series with a resistor, and the n parallel SiC MOSFETs are commonly connected to a loop consisting of a load inductor Ld, a DC bus capacitor Cdc, and a first DC power supply Vdc, as shown in FIG. Figure 1 As shown, the main power circuit consists of SiC MOSFET M1 and SiC MOSFET M2, a load inductor Ld, a DC bus capacitor Cdc, a first DC power supply Vdc, and two inductive inductors L1 and L2. The active drive circuit consists of a conventional drive circuit, a first non-inverting amplifier circuit, a first differential amplifier circuit, a first proportional current source circuit, a second non-inverting amplifier circuit, a second differential amplifier circuit, and a second proportional current source circuit. The conventional drive circuit consists of a drive voltage signal Vgs and two resistors Rg1 and Rg2. The first non-inverting amplifier circuit consists of two resistors E1 and E2 and an operational amplifier U1. The first differential amplifier circuit consists of four resistors R3 to R6 and an operational amplifier U2. The first proportional current source circuit consists of three transistors Q1 to Q3, three resistors R7 to R9, and a diode D1. The second non-inverting amplifier circuit consists of two resistors R 10 and R 11 , an operational amplifier U3, the second differential amplifier circuit consists of four resistors R 12 ~R 15 , an operational amplifier U4, the second proportional current source structure consists of three transistors Q4~Q6, three resistors R 16 ~R 18, a diode D2 is constituted. For the proportional current source circuit, the input is the second DC power supply VCC, and the output end acts on the gate of the SiC MOSFET. Specifically, the input of the first proportional current source circuit and the second proportional current source circuit is the second DC power supply VCC, and the output end respectively acts on the gate of the SiC MOSFET M1 and the gate of the SiC MOSFET M2 in the main power circuit. The base of Q1 in the first proportional current source circuit is the input end, the base of Q1, the output end of U1 in the first non-inverting amplifier circuit and the output end of U2 in the first differential amplifier circuit are connected with each other, the anode of diode D1 in the first proportional current source circuit is the output end, the anode of D1, the gate of the SiC MOSFET M1 in the main power circuit and the positive electrode of Vgs in the conventional drive circuit are connected with each other, the base of Q4 in the second proportional current source circuit is the input end, the base of Q4, the output end of U3 in the second non-inverting amplifier circuit and the output end of U4 in the second differential amplifier circuit are connected with each other, the anode of diode D2 in the second proportional current source circuit is the output end, the anode of diode D2, the gate of the SiC MOSFET M2 in the main power circuit and the positive electrode of Vgs in the conventional drive circuit are connected with each other; the first proportional current source circuit and the second proportional current source circuit are respectively used to extract the gate current when the SiC MOSFET M1 and the SiC MOSFET M2 are turned on, so as to balance the current difference when the two SiC MOSFETs are connected in parallel.

[0028] As Figure 2As shown, working process A is the initial current sharing state when SiC MOSFET is turned on. In working process A, when SiC MOSFET M1 and SiC MOSFET M2 are turned on, the current flowing through SiC MOSFET M1 and SiC MOSFET M2 starts to rise from 0. Under the action of the current flowing through the inductor L1, the inductor L1 generates an induced electromotive force at the source of SiC MOSFET M1. This induced electromotive force causes the inductor L1 to form an induced voltage VL1. The first non-inverting amplifier circuit detects and amplifies the induced voltage VL1. The amplified induced voltage VL1 is transmitted to the first proportional current source circuit in the form of an electrical signal, and then the current is extracted from the gate branch of SiC MOSFET M1 through the first proportional current source circuit. This process is the initial current sharing of the current flowing through SiC MOSFET M1 when SiC MOSFET M1 is turned on; under the action of the current flowing through the inductor L2, the inductor L2 generates an induced electromotive force at the source of SiC MOSFET M1. An induced electromotive force is generated at the source of M2, which causes the inductor L2 to form an induced voltage VL2. The second non-inverting amplifier circuit detects and amplifies the induced voltage VL2. The amplified induced voltage VL2 is transmitted to the second proportional current source circuit in the form of an electrical signal. The current is then extracted from the gate branch of SiC MOSFET M2 through the second proportional current source circuit. This process is the initial current sharing of the current flowing through SiC MOSFET M2 when SiC MOSFET M2 is turned on. The initial current sharing of SiC MOSFET M1 and SiC MOSFET M2 occurs simultaneously.

[0029] like Figure 3 As shown in FIG, under the condition of working process A, after SiC MOSFET M1 and SiC MOSFET M2 are turned on, the magnitudes of VL1 and VL2 are compared through the differential amplifier circuit. When it is detected that VL1 is greater than VL2, working process B is entered, and the first differential amplifier circuit starts to work and acts on the transistor Q1 in the first proportional current source circuit, controlling the transistor Q1 to turn on, and then using the first proportional current source circuit to extract current from the gate branch of SiC MOSFET M1, thereby improving the working state of SiC MOSFET M1. On the contrary, as Figure 4 As shown, under the condition that working process A exists, when it is detected that VL1 is less than VL2, working process C is entered, the second differential amplifier circuit starts to work, and acts on the transistor Q4 in the second proportional current source circuit to control the transistor Q4 to turn on, and then the second proportional current source circuit is used to extract current from the gate branch of SiC MOSFET M2, thereby improving the working state of SiCMOSFET M2. The role of working process B and working process C is to once again share the current of the SiC MOSFETs working in parallel.

[0030] In an ideal case, the induced voltages are equal, at this time, the turn-on and turn-off of the proportional current source circuit is only controlled by the in-phase amplification circuit, and in the actual working process, due to the difference of the parasitic parameters of the parallel discrete branches and the immature preparation process of the SiC MOSFET device, the on-resistance, threshold voltage, parasitic inductance, parasitic capacitance and other parameters of the SiC MOSFET will exist certain difference, which leads to the change of the value of the induced voltage with the change of the working condition, therefore, the dynamic and static current imbalance phenomenon inevitably occurs when the SiC MOSFET device works in parallel, for the SiC MOSFET source induced larger voltage, due to the earlier turn-on time, the corresponding proportional current source circuit extraction current time is longer, this characteristic is conducive to the current flowing through the SiC MOSFET.

[0031] Figure 5 As shown, taking the working condition of 20A load current as an example, the four curves in the figure present different current states from top to bottom, the uppermost curve shows the state of the current I1 extracted from the gate branch of the SiC MOSFET M1 before current sharing, at this time, the current presents a certain degree of fluctuation; the second curve is the state curve of the current I1 extracted from the gate branch of the SiC MOSFET M1 after current sharing, it can be seen that the current I1 after current sharing becomes relatively stable; the third curve represents the state of the current I2 extracted from the gate branch of the SiC MOSFET M2 before current sharing, the current also has fluctuation; the lowermost curve is the state curve of the current I2 extracted from the gate branch of the SiC MOSFET M2 after current sharing, the current I2 after current sharing also tends to be stable, from Figure 5 It can be clearly seen that the current I1 and the current I2 can realize current sharing faster after control and become more stable after current sharing. Therefore, using the current sharing control method in the application, the current imbalance problem in the turn-on process of the multiple SiC MOSFETs in parallel is effectively improved, the current imbalance degree of the multiple SiC MOSFETs in parallel is reduced, and the device working reliability is further improved.

[0032] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application but not to limit it, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A parallel current sharing system for silicon carbide MOSFETs in a pulsed power supply, characterized by: The main power circuit includes a plurality of SiC MOSFETs in parallel, and an active drive circuit; When the main power circuit is turned on with the plurality of SiC MOSFETs in parallel, the inductance at the source of the plurality of SiC MOSFETs generates an induced voltage proportional to the current rise rate; The active drive circuit includes a non-inverting amplifier circuit for detecting and amplifying the induced voltage, a differential amplifier circuit for detecting and comparing the value of the induced voltage, and a proportional current source circuit for extracting the gate current of the SiC MOSFET, and by detecting the induced voltage, amplifying the induced voltage, comparing the induced voltage, and extracting the gate current, the current balance of the plurality of SiC MOSFETs in parallel is realized.

2. The parallel current sharing system for silicon carbide MOSFETs of claim 1, wherein: The main power circuit has two SiC MOSFETs connected in parallel, namely SiC MOSFET M1 and SiC MOSFET M2. The main power circuit also includes a first DC power supply V dc , DC bus capacitor C dc , load inductance L d , diode D3, the sources of the two SiCMOSFETs are connected in series with an inductor and connected to the DC bus capacitor C dc One end, the first DC power supply V dc The negative electrodes of the two SiC MOSFETs are connected to each other and then to the ground. A resistor is connected in series to the gates of the two SiC MOSFETs and then to the driving signal source V gs The positive electrodes of the two SiC MOSFETs are connected to each other, and the drains of the two SiC MOSFETs are connected to each other and to the anode of the diode D3 and the load inductor L d One end of the load inductor L is connected to each other. d The other end of the first DC power supply V dc The positive electrode of the diode D3, the cathode of the diode D3 and the DC bus capacitor C dc The other ends of the SiC MOSFET M1 are connected to each other; the source of the SiC MOSFET M1 is connected in series with one end of the inductor L1, and the source voltage of the SiC MOSFET M1, the non-inverting input end of U1 in the first non-inverting amplifier circuit, one end of R5 in the first differential amplifier circuit, and R in the second differential amplifier circuit are connected in series. 12 The voltage at one end of the SiC MOSFET M2 is equal; the source of the SiC MOSFET M2 is connected in series with one end of the inductor L2, and the source voltage of the SiC MOSFET M2, the non-inverting input end of U3 in the second non-inverting amplifier circuit, one end of R3 in the first differential amplifier circuit, and R in the second differential amplifier circuit are all connected in series. 14 The voltage at one end is equal.

3. The parallel current sharing system for SiC MOSFETs of claim 2, wherein: The active drive circuit includes a conventional drive circuit, which is driven by a drive signal source V gs , resistor R g1 , resistor R g2 Composition, driving signal source V gs The positive electrode, resistor R g1 One end and resistor R g2 One end of each is connected to each other, driving signal source V gs The negative electrode of the inductor L1, the other end of the inductor L2, the first DC power supply V dc The negative electrode and DC bus capacitor C dc One end is connected to each other and grounded, driving the signal source V gs Drive SiC MOSFET M1 and SiC MOSFET M2 to turn on, and inductor L1 generates an induced voltage V L1 , inductor L2 generates an induced voltage V L2 .

4. The parallel current sharing system for silicon carbide MOSFETs of claim 3, wherein: The non-inverting amplifier circuit includes a first non-inverting amplifier circuit and a second non-inverting amplifier circuit. The first non-inverting amplifier circuit is composed of an operational amplifier U1, a resistor R1, and a resistor R2. One end of the resistor R1 is grounded, and the other end of the resistor R1, one end of the resistor R2, and the inverting input end of the operational amplifier U1 are connected to each other; the second non-inverting amplifier circuit is composed of an operational amplifier U3, a resistor R 10 , resistor R 11 Composition, resistor R 11 One end of the resistor R is grounded. 11 The other end of the resistor R 10 The first differential amplifier circuit is composed of an operational amplifier U2, a resistor R3, a resistor R4, a resistor R5, and a resistor R6. One end of the resistor R3, one end of the resistor R4, and the inverting input terminal of the operational amplifier U2 are connected to each other. One end of the resistor R6 is grounded. One end of the resistor R5, the other end of the resistor R6, and the non-inverting input terminal of the operational amplifier U2 are connected to each other. The second differential amplifier circuit is composed of an operational amplifier U4, a resistor R 12 , resistor R 13 , resistor R 14 , resistor R 15 Composition, resistor R 12 One end of the resistor R 13 One end of the resistor R 15 One end of the resistor R is grounded. 14 One end of the resistor R 15 The other end and the non-inverting input of the operational amplifier U4 are connected to each other; the induced voltage values ​​of the non-inverting input of the operational amplifier U1 in the first non-inverting amplifier circuit, the non-inverting input of the operational amplifier U2 in the first differential amplifier circuit and the source of the SiC MOSFET M1 are equal and are all V L1 The induced voltages at the non-inverting input of the operational amplifier U3 in the second non-inverting amplifier circuit, the non-inverting input of the operational amplifier U4 in the second differential amplifier circuit, and the source of the SiC MOSFET M2 are equal and are all V L2 , the V L1 The calculation formula is: The V L2 The calculation formula is: Wherein, L1 is the inductor connected in series with the source of SiC MOSFET M1 in the main power circuit, L2 is the inductor connected in series with the source of SiC MOSFET M2 in the main power circuit, di1 / dt represents the rate of change of current flowing through SiC MOSFET M1 per unit time, and di2 / dt represents the rate of change of current flowing through SiC MOSFET M2 per unit time.

5. The parallel current sharing system for silicon carbide MOSFETs for pulsed power supplies of claim 4, wherein: The proportional current source circuit comprises a first proportional current source circuit and a second proportional current source circuit, the first proportional current source circuit comprises an NPN transistor Q1, an NPN transistor Q2, an NPN transistor Q3, a resistor R7, a resistor R8, a resistor R9, a diode D1, a second direct current power supply V CC , the base of the NPN transistor Q1 is an input end of the first proportional current source circuit, the anode of the diode D1 is an output end of the first proportional current source circuit; the collector of the NPN transistor Q1 is connected with the second direct current power supply V CC , the emitter of the NPN transistor Q1 is connected with one end of the resistor R7, the other end of the resistor R7, the collector of the NPN transistor Q2, the base of the NPN transistor Q2 and the base of the NPN transistor Q3 are connected with each other, the emitter of the NPN transistor Q2 is connected with one end of the resistor R8, the collector of the NPN transistor Q3 is connected with the cathode of the diode D1, the emitter of the NPN transistor Q3 is connected with one end of the resistor R9, the other end of the resistor R8 and the other end of the resistor R9 are connected with each other and grounded, the anode of the diode D1, the gate of the SiC MOSFET M1 and the other end of the resistor R g1 are connected with each other; the second proportional current source circuit comprises an NPN transistor Q4, an NPN transistor Q5, an NPN transistor Q6, a resistor R 16 , a resistor R 17 , a resistor R 18 , a diode D2, a second direct current power supply V CC , the base of the NPN transistor Q4 is an input end of the second proportional current source circuit, the anode of the diode D2 is an output end of the second proportional current source circuit; the collector of the NPN transistor Q4 is connected with the second direct current power supply V CC , the emitter of the NPN transistor Q4 is connected with one end of the resistor R 16 , the other end of the resistor R 16 , the collector of the NPN transistor Q5, the base of the NPN transistor Q5 and the base of the NPN transistor Q6 are connected with each other, the emitter of the NPN transistor Q5 is connected with one end of the resistor R 17 , the collector of the NPN transistor Q6 is connected with the cathode of the diode D2, the emitter of the NPN transistor Q6 is connected with one end of the resistor R 18 , the other end of the resistor R 17 and the other end of the resistor R 18 are connected with each other and grounded, the anode of the diode D2, the gate of the SiC MOSFET M2 and the other end of the resistor R g2 are connected with each other.

6. The method of claim 5, wherein the parallel current sharing system of silicon carbide MOSFETs for a pulsed power supply is characterized by: The method comprises the following steps: Step 1: Working process A is the initial current sharing state when two SiC MOSFETs are turned on. When SiC MOSFET M1 and SiC MOSFET M2 are turned on, the inductance L1 connected in series with the source of SiC MOSFET M1 generates an induced voltage V L1 , the inductance L2 connected in series with the source of SiC MOSFET M2 generates an induced voltage V L2 , the detected induced voltage V L1 is amplified by the first non-inverting amplifier circuit and then the current is extracted from the branch of the gate of SiC MOSFET M1 through the first proportional current source circuit; the detected induced voltage V L2 is amplified by the first non-inverting amplifier circuit and then the current is extracted from the branch of the gate of SiC MOSFET M2 through the second proportional current source circuit; Step 2: in the presence of working process A, the amplified induced voltage is compared by the differential amplification circuit, when V L1 is greater than V L2 , enter working process B, at this time the first differential amplification circuit acts on the first proportional current source circuit and controls the opening of the transistor Q1 in the first proportional current source circuit, and then extracts current from the gate branch of SiC MOSFET M1 again for current sharing; when V L1 is less than V L2 , enter working process C, at this time the second differential amplification circuit acts on the second proportional current source circuit and controls the opening of the transistor Q4 in the second proportional current source circuit, and then extracts current from the gate branch of SiC MOSFET M2 again for current sharing.

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