Single drive controlled series SiC MOSFET DC solid-state circuit breaker and power distribution system

Abstract

The present invention relates to a series SiC MOSFET DC solid-state circuit breaker and a power distribution system with single-drive control. The DC solid-state circuit breaker includes a SiC MOSFET drive circuit, SiC MOSFET devices M1 to M n , drive resistors R g1 to R gn , diodes D1 to D n‑1 , an RCD buffer circuit, varistors MOV and varistor MOV cs ; one end of the SiC MOSFET drive circuit is connected to the source electrode of the SiC MOSFET device M1, and the output end of the SiC MOSFET drive circuit is connected to the gate electrode of the SiC MOSFET device M1 through the drive resistor R g1 ; the output end of the SiC MOSFET drive circuit is connected in series with diodes D1 to D n‑1 at the same time, and the diodes D1 to D n‑1 are respectively connected to the gate electrodes of the SiC MOSFET devices M2 to M n through their respective drive resistors; each of the SiC MOSFET devices M2 to M n is connected with a zener diode. The anode of the zener diode is connected to the source electrode of the SiC MOSFET device, and the cathode of the zener diode is connected to the gate electrode of the SiC MOSFET device. The problem of gate oscillation of the device is solved, and the conduction loss is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of DC solid-state circuit breakers, and in particular relates to a single-drive-controlled series SiC MOSFET DC solid-state circuit breaker and a power distribution system. Background Art

[0002] DC solid-state circuit breakers with SiC MOSFET devices as the main control switch are suitable for short-circuit fault protection of DC power systems due to their excellent switching characteristics such as fast switching speed, low conduction loss, and strong fault tolerance. Although solid-state circuit breakers with SiC MOSFET devices as the main control switch have very excellent switching characteristics, they are limited by the withstand voltage level of a single SiC MOSFET device, and multiple SiC MOSFET devices are usually connected in series to form a DC solid-state circuit breaker to adapt to higher voltage levels.

[0003] In order to reduce the cost and system complexity of solid-state circuit breakers with series devices, a series SiC MOSFET solid-state circuit breaker structure controlled by a single drive circuit is proposed. In this structure, only a standard drive circuit and a small number of passive devices are used to realize the on-off control of multiple series devices, which greatly reduces the cost and system complexity of the solid-state circuit breaker and simplifies the control. The single switch characteristics of the devices in the solid-state circuit breaker enable the series devices in the solid-state circuit breaker to limit the maximum voltage at both ends of the device by connecting a metal oxide varistor (MOV) in parallel at both ends, thereby solving the problem of dynamic voltage balancing between series devices in a single-drive solid-state circuit breaker, and further providing the conditions for the realization of a single-drive solid-state circuit breaker.

[0004] The currently proposed solid-state circuit breaker structure based on single drive control with capacitor coupling has a gate oscillation problem, which can cause some devices to be mis-conducted during the voltage recovery phase of fault interruption, and lead to uneven voltage between series devices, thereby affecting the reliability of the entire circuit breaker shutdown. In order to improve the gate oscillation problem, the prior art further adds a unidirectional conducting diode to the main branch of the circuit breaker, but increases the conduction loss of the entire circuit breaker. Summary of the invention

[0005] In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a single drive-controlled series SiC MOSFET DC solid-state circuit breaker and a power distribution system.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] On the one hand, the present invention provides a single drive-controlled series SiC MOSFET DC solid-state circuit breaker, comprising a SiC MOSFET drive circuit, SiC MOSFET devices M1 to M2 n , driving resistance R g1 ~R gn , diode D1~D n-1 , RCD snubber circuit, MOV varistor and MOV varistor cs ; n is a positive integer greater than or equal to 2;

[0008] Each SiC MOSFET device corresponds to an RCD snubber circuit and a varistor MOV. The two ends of the varistor MOV are connected to the source and drain of the SiC MOSFET device. The capacitor of each RCD snubber circuit is connected in parallel with a varistor MOV. cs , MOV varistor and MOV varistor cs The model is the same;

[0009] The drain of the previous SiC MOSFET device is connected to the source of the next SiC MOSFET device to realize SiCMOSFET devices M1 to M n One end of the SiC MOSFET driving circuit is connected to the source of the SiC MOSFET device M1, and the output end of the SiC MOSFET driving circuit is connected to the source of the SiC MOSFET device M1 through the driving resistor R g1 The output end of the SiCMOSFET driving circuit is connected to the gate of the SiCMOSFET device M1; the output end of the SiCMOSFET driving circuit is also connected in series with diodes D1 to D n-1 , diode D1~D n-1 Through their respective driving resistors, they are connected to SiC MOSFET devices M2~M n Gate connection of SiC MOSFET devices M2~M n A Zener diode is connected to each, the anode of the Zener diode is connected to the source of the SiC MOSFET device, and the cathode of the Zener diode is connected to the gate of the SiC MOSFET device.

[0010] Furthermore, the RCD snubber circuit includes a diode D S , capacitor C S and resistor R S ; diode D S With resistor R s Parallel connection, diode D S The cathode and capacitor C s One end of the capacitor C s The other end is connected to the source of the corresponding SiC MOSFET device, and the varistor MOV cs Connected in parallel with capacitor Cs The two ends of the RCD snubber circuit are connected to the diode D S The anode of the RCD snubber is connected to the gate of the next SiC MOSFET device. S The anode of the SiC MOSFET is connected to the drain of the corresponding SiC MOSFET device.

[0011] On the other hand, the present invention provides a DC power distribution system, comprising a DC power supply, a current limiting inductor, a DC solid-state circuit breaker and a load connected in series in sequence; the DC solid-state circuit breaker is the above-mentioned single-drive-controlled series SiC MOSFET DC solid-state circuit breaker.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1. The diode and resistor of the RCD snubber circuit are connected in parallel, the cathode of the diode is connected to one end of the capacitor, and the anode of the diode of the previous RCD snubber circuit is connected to the gate of the next SiC MOSFET device. When the voltage across the SiC MOSFET device M1 drops from the high clamping voltage of the MOV to the bus voltage, the capacitor C s1 and MOV varistor cs1 The discharge current flowing through the gate capacitance of SiCMOSFET device M2 is blocked by the unidirectional diode D s1 The discharge current no longer flows through the gate capacitance of the SiC MOSFET device M2, but can only flow through the resistor R s1 discharge, thus avoiding the capacitor C s1 The oscillation problem caused by the discharge on the gate voltage of the SiC MOSFET device M2 makes the gate voltage of the SiC MOSFET device M2 tend to be stable. The present invention solves the gate oscillation problem in the original single drive structure by only using the diode in the RCD buffer circuit, while improving the shutdown reliability of the entire circuit breaker and avoiding adding too many passive devices, thus ensuring the economy of the entire structure.

[0014] 2. In the circuit breaker structure of the present invention, except for the two SiC MOSFET devices which have conduction losses when the normal load current flows through the circuit breaker during normal operation, the other components in the structure do not flow the normal load current, that is, no conduction losses are generated, thereby reducing the conduction losses of the circuit breaker.

[0015] 3. The circuit breaker of the present invention connects varistors with the same parameters in parallel at the drain-source end of the SiC MOSFET device and at both ends of the buffer capacitor, so that in the inductive energy release stage, the short-circuit current flows through two branches containing varistors to release energy. Therefore, compared with the energy release channel consisting of only one varistor, the current flowing through the Zener diode branch of the device M2 is theoretically reduced by half, avoiding the problem of large current flowing through the Zener diode and improving the safety of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The topological structure diagram of a DC solid-state circuit breaker consisting of two SiC MOSFET devices connected in series;

[0017] Figure 2 The topological structure diagram of a DC solid-state circuit breaker consisting of three SiC MOSFET devices connected in series;

[0018] Figure 3 It is the topological structure diagram of DC power distribution system;

[0019] Figure 4 The topological structure diagram of the single drive control solid-state circuit breaker based on capacitive coupling proposed in the existing literature;

[0020] Figure 5 This is the equivalent discharge schematic diagram of the single-drive controlled solid-state circuit breaker based on capacitive coupling proposed in the existing literature during the voltage recovery stage;

[0021] Figure 6 The simulation waveform diagram of the single drive control solid-state circuit breaker based on capacitive coupling proposed in the existing literature;

[0022] Figure 7 It is a simulation waveform diagram of the single-drive-controlled series SiC MOSFET DC solid-state circuit breaker of the present invention. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings and specific implementation methods, but the protection scope of the present application is not limited thereto.

[0024] The present invention is a single drive controlled series SiC MOSFET DC solid-state circuit breaker, comprising a SiC MOSFET drive circuit, SiC MOSFET devices M1 to M2 n , driving resistance R g1 ~R gn , diode D1~D n-1 , RCD snubber circuit, MOV varistor and MOV varistor csEach SiC MOSFET device corresponds to an RCD snubber circuit and a varistor MOV. The two ends of the varistor MOV are connected to the source and drain of the SiC MOSFET device. The capacitor of each RCD snubber circuit is connected in parallel with a varistor MOV. cs , MOV varistor and MOV varistor cs The models are the same; n is a positive integer greater than or equal to 2;

[0025] The drain of the previous SiC MOSFET device is connected to the source of the next SiC MOSFET device to realize SiCMOSFET devices M1 to M n The SiC MOSFET driving circuit is used as a signal generating circuit. One end of the SiC MOSFET driving circuit is connected to the source of the SiC MOSFET device M1. The output end of the SiC MOSFET driving circuit is connected to the source of the SiC MOSFET device M1 through the driving resistor R g1 The output end of the SiC MOSFET driving circuit is also connected in series with diodes D1 to D n-1 , diode D1~D n-1 Through their respective driving resistors, they are connected to SiC MOSFET devices M2~M n The gate connection of diodes D1~D n-1 The function is: when the corresponding SiC MOSFET device is turned on, it provides a current path for the SiC MOSFET device; when the corresponding SiC MOSFET device is turned off, it is used to withstand high voltage; SiC MOSFET devices M2~M n Each is connected with a Zener diode, the anode of the Zener diode is connected to the source of the SiC MOSFET device, and the cathode of the Zener diode is connected to the gate of the SiC MOSFET device, which is used to limit the gate voltage of the SiC MOSFET device to prevent the SiC MOSFET device from being damaged due to excessive transient voltage when it is turned off;

[0026] The RCD snubber circuit includes a diode D S , capacitor C S and resistor R S , diode D S With resistor R s Parallel connection, diode D S The cathode and capacitor C s One end of the capacitor C s The other end is connected to the source of the corresponding SiC MOSFET device, and the varistor MOV cs Connected in parallel with capacitor C s The two ends of the RCD snubber circuit are connected to the diode D SThe anode of the RCD snubber is connected to the gate of the next SiC MOSFET device. S The anode of the RCD snubber circuit is connected to the drain of the corresponding SiC MOSFET device. S The upper SiC MOSFET device is controlled by the switch state of the lower SiC MOSFET device. S The gate oscillation problem during the voltage recovery process is solved; the capacitor of the RCD snubber circuit not only limits the voltage rise time of the upper SiC MOSFET device through the charging process, but also plays a role in driving the upper SiC MOSFET device; the diode D S Make the capacitor C S During the charging process, the connection between the lower SiC MOSFET device voltage and the drive voltage is established. S During the oscillation discharge process, the diode D S Cut off the capacitor C S The connection with the lower SiC MOSFET device voltage and driving voltage ensures the stability of the driving voltage.

[0027] Example

[0028] Taking two SiC MOSFET devices connected in series as an example, the single-drive-controlled series SiC MOSFET DC solid-state circuit breaker of the present invention is described in detail; Figure 1 As shown, the circuit breaker includes a SiC MOSFET drive circuit, SiC MOSFET devices M1-M2, and a drive resistor R g1 ~R g2 , diode D1, Zener diode Z d1 , a first RCD snubber circuit, a second RCD snubber circuit, varistors MOV1 to MOV2 and varistors MOV cs1 ~MOV cs2 ; The first RCD snubber circuit includes a diode D S1 , capacitor C S1 and resistor R S1 , the second RCD snubber circuit includes a diode D S2 , capacitor C S2 and resistor R S2 ;

[0029] The drain of SiC MOSFET device M1 is connected to the source of SiC MOSFET device M2, and the voltage regulator diode Z d1 The anode and cathode of the SiC MOSFET device M1 are connected to the source and gate, respectively. The voltage regulator diode Z d1The anode and cathode of the SiC MOSFET device M2 are connected to the source and gate of the SiC MOSFET device M2 respectively; one end of the SiC MOSFET driving circuit is connected to the source of the SiC MOSFET device M1, and the output end of the SiC MOSFET driving circuit is connected to the source of the SiC MOSFET device M1 through the driving resistor R g1 Connected to the gate of SiC MOSFET device M1, the output end of the SiC MOSFET drive circuit is connected through diode D1 and drive resistor R g2 connected to the gate of the SiC MOSFET device M2; the SiC MOSFET driving circuit is used to provide an on / off signal to the SiC MOSFET device M1. When the SiC MOSFET driving circuit outputs a high level, the gate-source voltage of the SiC MOSFET device M1 is a high level, and the SiC MOSFET device M1 is turned on; when the SiC MOSFET driving circuit outputs a low level, the gate-source voltage of the SiC MOSFET device M1 is a low level, and the SiC MOSFET device M1 is turned off;

[0030] Diode D S1 With resistor R S1 Parallel connection, diode D S1 The anode of the SiC MOSFET device M2 is connected to the gate of the diode D S1 The cathode and capacitor C S1 One end of the capacitor C S1 The other end is connected to the source of SiC MOSFET device M1; varistor MOV cs1 Connected in parallel with capacitor C S1 The two ends of the varistor MOV1 are connected to the source and drain of the SiC MOSFET device M1; similarly, the diode D S2 With resistor R S2 Parallel connection, diode D S2 The anode of the SiC MOSFET device M2 is connected to the drain of the diode D S2 The cathode and capacitor C S2 One end of the capacitor C S2 The other end is connected to the source of SiC MOSFET device M2; varistor MOV cs2 Connected in parallel with capacitor C S2 The two ends of the varistor MOV2 are connected to the source and drain of the SiC MOSFET device M2; the varistor MOV cs1 and MOV cs2 To limit the capacitance C S1 and C S2 The varistors MOV1 and MOV2 are used to limit the voltage of the SiC MOSFET devices M1 and M2.

[0031] Varistors MOV1~MOV2 and varistor MOV cs1 ~MOV cs2 The same model, varistor MOV cs1 , MOV1 and R s1 , and MOV varistor cs2 , MOV2 and R s2 Two structures with the same resistance are formed in the same connection mode. According to the resistance voltage division principle, the two structures with the same resistance are connected in parallel to the drain and source of the SiC MOSFET devices M1 and M2, respectively, so as to realize voltage equalization when the SiC MOSFET devices M1 and M2 are turned off, so that the SiC MOSFET devices M1 and M2 bear half of the bus voltage respectively.

[0032] The specific working principle is: when the SiC MOSFET device M1 receives the shutdown signal to shut down, the voltage V across the SiC MOSFET device M1 ds1 The voltage rises, and the voltage rise leads to the voltage rise of the parallel part, that is, the diode D s1 With capacitor C S1 The branch voltage rises, so the charging current is given to the capacitor C of the first RCD snubber circuit S1 The charging current is fed to the capacitor C S1 While charging, it flows through the gate of SiC MOSFET device M2, discharging the gate capacitance of SiC MOSFET device M2, thereby reducing the gate voltage of SiC MOSFET device M2, and SiC MOSFET device M2 starts to turn off, and finally as the voltage V across SiC MOSFET device M1 increases ds1 As the gate voltage of the SiC MOSFET device M2 drops below the threshold voltage, the SiC MOSFET device M2 is completely turned off. When the device is completely turned off and the blocking voltage drops from the high voltage to the bus voltage, the capacitor C S1 The discharge will cause the voltage to drop. At this time, the diode D s1 Blocking capacitor C S1 Through the discharge channel of the SiC MOSFET device M2 gate, the capacitor C S1 Through the resistor R S1 discharge, thus avoiding the capacitor C S1 The effect of discharge on the gate voltage of the SiC MOSFET device M2 is reduced, thereby solving the problem of gate oscillation and ensuring the stable shutdown of the SiC MOSFET device M2 during fault isolation.

[0033] The single-drive controlled series SiC MOSFET DC solid-state circuit breaker of the present invention is mainly used for fault protection of DC power distribution systems above 1kV. In order to verify the effectiveness of the circuit breaker, the circuit breaker is connected in series to the DC power distribution system, which includes a DC power supply, a current limiting inductor, a DC solid-state circuit breaker and a load. Figure 3 The current limiting inductor is 500uH, the SiC MOSFET device is the C3M0032120D device from Wolfspeed, and the diode D s1 , D s2 , D1 are fast recovery diodes, driving resistor R g1 , R g2 The resistor R is 10 ohms. s1 , R s2 is 200 ohms, capacitor C s1 , C s2 is 2.2nF, Zener diode Z d1 , Z d1 The clamping voltage is 15V, and the varistor MOV1, MOV2, MOV cs1 、MOV cs2 The specific parameters are selected according to the bus voltage and the withstand voltage of the SiC MOSFET device; when a system fault occurs, the fault detection device sends a protection interrupt signal to the circuit breaker. After the circuit breaker receives the protection interrupt signal, the drive circuit outputs a shutdown signal to reduce the gate voltage of the SiC MOSFET device M1, and the SiC MOSFET device M1 starts to shut down; when the SiC MOSFET device M1 is turned off, the voltage across it rises, and the increase in voltage causes the gate voltage of the SiC MOSFET device M2 to drop, so that the SiC MOSFET device M2 starts to shut down, and finally both the SiC MOSFET devices M1 and M2 are shut down. After experiencing the inductive energy release stage and the voltage recovery stage, the entire solid-state circuit breaker returns to the steady state when it is turned off, that is, the circuit breaker completes the fault protection and successfully isolates the fault.

[0034] Figure 4 A capacitor-coupled single-drive-controlled solid-state circuit breaker structure proposed in existing literature is used. The circuit breaker structure in the existing literature and the circuit breaker structure of the present invention are simulated and compared under a bus voltage of 1200V. Figure 5 The equivalent circuit diagram of the solid-state circuit breaker structure based on single drive control of capacitor coupling proposed in the existing literature during the voltage recovery stage, the dotted line is the flow path of the equivalent discharge current i1; Figure 5 It can be seen that the voltage V ds When the clamping voltage of MOV drops to the bus voltage, the parasitic capacitance C1 of capacitor C1 and varistor C mov1The voltage drops and discharges, thus generating a discharge current i1, which flows through the equivalent capacitance C of the SiC MOSFET device M2. gd2 and C gs2 -C ds2 Two branches, the current-limiting inductor L that eventually flows to the line limit , when the discharge current flows through the C of SiC MOSFET device M2 gs2 -C ds2 When the capacitor C gs2 Charge, so that the gate voltage V gs2 Rising, when V gs2 When the voltage exceeds the device threshold voltage, it will cause the SiC MOSFET device M2 to turn on again, that is, mis-turn on occurs. Figure 6 , 7 They are respectively the simulation waveforms of the single drive controlled solid-state circuit breaker structure proposed in the prior art and the present invention. Figure 6 From the simulation results, we can see that the voltage V ds2 The drop in the drain-source voltage V ds1 、V ds2 There is a clear uneven pressure. Figure 7 It can be seen that for the circuit breaker of the present invention, the voltage V ds When the clamping voltage of MOV drops to the bus voltage, the capacitor C s1 and MOV varistor cs1 During discharge, the current flowing through the gate capacitance of the SiC MOSFET device M2 is blocked by the unidirectional diode D s1 The discharge current no longer flows through the gate capacitance of the SiC MOSFET device M2, but can only flow through the resistor R s1 discharge, thus avoiding the capacitor C s1 Discharge effect on the gate voltage V of SiC MOSFET device M2 gs2 The influence of makes the gate voltage of SiC MOSFET device M2 stable, and device M2 can be turned off stably. In the simulation waveform, it is reflected as the voltage V ds1 and V ds2 Always maintain good pressure balance.

[0035] Any matters not described in the present invention are applicable to the prior art.

Claims

1. A single drive controlled series SiC MOSFET DC solid-state circuit breaker, characterized in that: The circuit breaker includes a SiC MOSFET drive circuit, SiC MOSFET devices M1 to M n , driving resistance R g1 ~R gn , diode D1~D n-1 , RCD snubber circuit, MOV varistor and MOV varistor cs ; n is a positive integer greater than or equal to 2; Each SiC MOSFET device corresponds to an RCD snubber circuit and a varistor MOV. The two ends of the varistor MOV are connected to the source and drain of the SiC MOSFET device. The capacitor of each RCD snubber circuit is connected in parallel with a varistor MOV. cs , MOV varistor and MOV varistor cs The model is the same; The drain of the previous SiC MOSFET device is connected to the source of the next SiC MOSFET device to realize SiC MOSFET devices M1 to M n One end of the SiC MOSFET driving circuit is connected to the source of the SiC MOSFET device M1, and the output end of the SiC MOSFET driving circuit is connected through the driving resistor R g1 The output end of the SiC MOSFET driving circuit is also connected in series with diodes D1 to D n-1 , diode D1~D n-1 Through their respective driving resistors, they are connected to the SiCMOSFET devices M2~M n Gate connection of SiC MOSFET devices M2~M n Each is connected with a Zener diode, the anode of the Zener diode is connected to the source of the SiC MOSFET device, and the cathode of the Zener diode is connected to the gate of the SiC MOSFET device; The RCD snubber circuit includes a diode D S , capacitor C S and resistor R S ; diode D S With resistor R s Parallel connection, diode D S The cathode and capacitor C s One end of the capacitor C s The other end is connected to the source of the corresponding SiC MOSFET device, and the varistor MOV cs Connected in parallel with capacitor C s The two ends of the RCD snubber circuit are connected to the diode D S The anode of the RCD snubber is connected to the gate of the next SiC MOSFET device. S The anode of the SiC MOSFET is connected to the drain of the corresponding SiC MOSFET device.

2. A DC power distribution system, comprising a DC power supply, a current limiting inductor, a DC solid-state circuit breaker and a load connected in series in sequence; characterized in that: The DC solid-state circuit breaker is the single-drive-controlled series SiC MOSFET DC solid-state circuit breaker according to claim 1.

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