Monitoring device for desaturation fault and vehicle

Abstract

The invention discloses a desaturation fault monitoring device and a vehicle. The desaturation fault monitoring device comprises a power supply circuit, a monitoring circuit, a control circuit and a driving circuit, the output end of the power circuit is connected with the first input end of the control circuit. The power circuit is used for providing electric energy for the control circuit. The first output end of the control circuit is connected with the monitoring circuit, and the second output end of the control circuit is connected with the driving circuit; the first output end of the monitoring circuit is connected with the control circuit, and the output end of the driving circuit is connected with a to-be-tested power device; the monitoring circuit is used for transmitting fault information to the control circuit when monitoring that the to-be-tested power device has a desaturation fault, and the control circuit generates a driving signal based on the fault information to control the driving circuit to turn off the to-be-tested power device. The monitoring device provided by the invention can effectively reduce the charging current of the capacitor and improve the robustness of the driving power device.

Description

Technical Field

[0001] The present invention relates to the field of circuit technology, and in particular to a desaturation fault monitoring device and a vehicle. Background Art

[0002] Si-based IGBT (Insulated Gate Bipolar Transistor) and SiC-based field-effect transistor (Metal-Oxide-Semiconductor Field-Effect Transistor) are two widely used power devices. Compared with Si materials, SiC materials have the characteristics of large bandgap, high switching frequency, low on-resistance, and high thermal conductivity, and are widely used in high-frequency, high-power density, and high-temperature fields. However, high switching speeds are prone to voltage and current overshoot and electromagnetic compatibility problems. Voltage and current overshoots of power devices will reduce their use, and in severe cases will cause irreversible damage during power operation, reducing reliability during power operation. SiC has weak short-circuit capability, which is mainly reflected in: short short-circuit tolerance time and fast temperature rise rate. In addition, during high-speed switching, SiC will generate high-frequency coupling current through parasitic capacitance in the device and loop, causing false triggering of short-circuit faults and causing false shutdown of power devices. All of these put forward higher requirements for SiC's short-circuit protection circuit, that is, accurately capture short-circuit faults and quickly shut down power devices.

[0003] The desaturation fault protection circuit (DESAT) is the most typical short-circuit protection circuit, which is generally integrated into the driver chip of the power device. The DESAT parameters in the existing driver chips are mostly designed around SiIGBT devices. However, there are obvious differences in the short-circuit characteristics between SiC MOSFET and Si IGBT: the short-circuit tolerance time of SiC power devices is much shorter than that of Si-based power devices. Therefore, the requirements for the short-circuit response rate of Si IGBT are lower than those of SiC MOSFET. The rapid change in voltage when the power device is turned off will charge the sampling capacitor through the junction capacitance of the diode. If the current is too large, the voltage across the sampling capacitor will reach the threshold voltage, resulting in the malfunction of DESAT and the erroneous shutdown of the power device. Summary of the invention

[0004] The present invention provides a monitoring device for desaturation faults. A monitoring circuit is provided to monitor the voltage of a power device. When a desaturation fault is detected in the power device, a control circuit generates a driving signal based on a fault signal to control the driving circuit to shut down the power device to protect the power device from being damaged, thereby improving the robustness of driving the power device.

[0005] According to a first aspect of the present invention, there is provided a monitoring device for a desaturation fault, comprising a power supply circuit, a monitoring circuit, a control circuit and a drive circuit;

[0006] The output end of the power supply circuit is connected to the first input end of the control circuit, and the power supply circuit is used to provide electrical energy to the control circuit;

[0007] The first output terminal of the control circuit is connected to the monitoring circuit, and the second output terminal of the control circuit is connected to the driving circuit;

[0008] The first output terminal of the monitoring circuit is connected to the control circuit, and the output terminal of the driving circuit is connected to the power device to be tested;

[0009] The monitoring circuit is used to transmit fault information to the control circuit when detecting a desaturation fault in the power device under test, and the control circuit generates a drive signal based on the fault information to control the drive circuit to shut down the power device under test.

[0010] Optionally, the monitoring circuit includes a first switch tube, a second switch tube, a first resistor, a first capacitor and a hysteresis comparator;

[0011] The first end of the first switch tube is connected to the power supply, the second end of the first switch tube is connected to the first end of the first resistor; the third end of the first switch tube is connected to the first input end of the control circuit;

[0012] The first end of the second switch tube is connected to the second end of the first resistor, the second end of the second switch tube is grounded, and the third end of the second switch tube is connected to the second input end of the control circuit;

[0013] The first capacitor is connected in parallel with the second switch tube; the input end of the hysteresis comparator is connected to the first end of the first capacitor, and the output end of the hysteresis comparator is connected to the third input end of the control circuit.

[0014] Optionally, the monitoring circuit further includes a second resistor and a third resistor;

[0015] The first end of the second resistor is connected to the second end of the first resistor, and the second end of the second resistor is connected to the first end of the first capacitor; the first end of the third resistor is connected to the second end of the second resistor, and the second end of the third resistor is connected to the first end of the second switch tube.

[0016] Optionally, the monitoring circuit further includes a first diode;

[0017] A first end of the first diode is connected to a first end of the first capacitor; and a second end of the first diode is grounded.

[0018] Optionally, the monitoring circuit further includes a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, and a ninth resistor;

[0019] The first positive terminal of the hysteresis comparator is connected to the first end of the eighth resistor, the second end of the eighth resistor is connected to the first end of the ninth resistor, and the second end of the ninth resistor is connected to the third input end of the control circuit; the first negative terminal of the hysteresis comparator is grounded through the fifth resistor;

[0020] The second positive terminal of the hysteresis comparator is grounded, and the second negative terminal of the hysteresis comparator is connected to the output terminal of the hysteresis comparator;

[0021] The sixth resistor is connected in series with the seventh resistor, the first end of the sixth resistor is connected to the first negative terminal of the hysteresis comparator, and the second end of the seventh resistor is connected to the first end of the ninth resistor; the first end of the fourth resistor is connected to the second end of the second resistor, and the second end of the fourth resistor is connected to the first positive terminal of the hysteresis comparator.

[0022] Optionally, the monitoring circuit further includes a second diode;

[0023] The first end of the second diode is connected to the first electrode of the power device to be tested, and the second end of the second diode is connected to the second end of the first resistor.

[0024] Optionally, the control circuit includes a control module, a third switch tube and a fourth switch tube;

[0025] The first output end of the control module is connected to the third end of the third switch tube, and the second output end of the control module is connected to the third end of the fourth switch tube;

[0026] The first end of the third switch tube is connected to the positive voltage end, the second end of the third switch tube is connected to the first end of the fourth switch tube; the second end of the fourth switch tube is connected to the negative voltage end.

[0027] Optionally, the first electrode of the power device to be tested is connected to the input end of the monitoring circuit, and the second electrode of the power device to be tested is connected to the control end of the control circuit.

[0028] Optionally, the power device to be tested includes a silicon carbide power device.

[0029] According to a second aspect of the present invention, there is provided a vehicle, comprising a monitoring device for desaturation fault as described in any one of the first aspects.

[0030] The present invention discloses a monitoring device for desaturation fault, comprising a power supply circuit, a monitoring circuit, a control circuit and a driving circuit; the output end of the power supply circuit is connected to the first input end of the control circuit, and the power supply circuit is used to provide electric energy for the control circuit; the first output end of the control circuit is connected to the monitoring circuit, and the second output end of the control circuit is connected to the driving circuit; the first output end of the monitoring circuit is connected to the control circuit, and the output end of the driving circuit is connected to the power device to be tested; the monitoring circuit is used to transmit the fault information to the control circuit when the desaturation fault occurs in the power device to be tested, and the control circuit generates a driving signal based on the fault information to control the driving circuit to turn off the power device to be tested. In the monitoring device for desaturation fault provided by the present invention, the monitoring circuit is set to monitor the voltage of the power device, and when the desaturation fault occurs in the power device, the control circuit generates a driving signal based on the fault signal to control the driving circuit to turn off the power device to protect the power device from being damaged, thereby improving the robustness of driving the power device.

[0031] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 It is a structural schematic diagram of a desaturation fault monitoring device provided by an embodiment of the present invention;

[0034] Figure 2 is a circuit schematic diagram of a desaturation fault monitoring device provided by an embodiment of the present invention;

[0035] Figure 3 is an equivalent circuit diagram of a hysteresis comparator in a desaturation fault monitoring device provided by an embodiment of the present invention;

[0036] Figure 4 is an equivalent circuit diagram of a hysteresis comparator in another desaturation fault monitoring device provided by an embodiment of the present invention;

[0037] Figure 5 It is a circuit principle diagram of another desaturation fault monitoring device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings 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 should fall within the scope of protection of the present invention.

[0039] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device 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 inherent to these processes, methods, products or devices. It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in the present invention can be executed in parallel, can be executed sequentially, or can be executed in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document is not limited here.

[0040] Figure 1 is a schematic diagram of the structure of a desaturation fault monitoring device provided by an embodiment of the present invention, with reference to Figure 1 The desaturation fault monitoring device provided by the embodiment of the present invention includes a power supply circuit 1, a monitoring circuit 2, a control circuit 3 and a drive circuit 4; the output end of the power supply circuit 1 is connected to the first input end of the control circuit 3, and the power supply circuit 1 is used to provide electric energy to the control circuit 3; the first output end of the control circuit 3 is connected to the monitoring circuit 2, and the second output end of the control circuit 3 is connected to the drive circuit 4; the first output end of the monitoring circuit 2 is connected to the control circuit 3, and the output end of the drive circuit 4 is connected to the power device 5 to be tested; the monitoring circuit 2 is used to transmit the fault information to the control circuit 3 when detecting that the power device 5 to be tested has a desaturation fault, and the control circuit 3 generates a drive signal based on the fault information to control the drive circuit 4 to turn off the power device 5 to be tested.

[0041] Among them, desaturation failure refers to the process in which a power device exits the saturation region and enters the active region or cut-off region due to changes in certain external or internal conditions when it is in the on state, which may cause damage to the power device.

[0042] Specifically, the output end of the power supply circuit 1 is connected to the first input end of the control circuit 3 to supply power to the control circuit 3. The first output end of the control circuit 3 is connected to the monitoring circuit 2. The first output end of the monitoring circuit 2 is connected to the control circuit 3. When a desaturation fault occurs in the power device 5 to be tested, the monitoring circuit 2 detects that the voltage at both ends of the power device 5 to be tested is abnormally increased. The monitoring circuit 2 transmits the fault information to the control circuit 3. The control circuit 3 generates a driving signal based on the fault information and transmits it to the driving circuit 4. After receiving the driving signal, the driving circuit 4 turns off the power device 5 to be tested to protect the power device 5 to be tested from being damaged.

[0043] Figure 2 is a circuit schematic diagram of a desaturation fault monitoring device provided by an embodiment of the present invention, with reference to Figure 2 Optionally, the monitoring circuit includes a first switch tube Q1, a second switch tube Q2, a first resistor R1, a first capacitor C1 and a hysteresis comparator A; the first end of the first switch tube Q1 is connected to the power supply VCC, and the second end of the first switch tube Q1 is connected to the first end of the first resistor R1; the third end of the first switch tube Q1 is connected to the first input end of the control circuit 3; the first end of the second switch tube Q2 is connected to the second end of the first resistor R1, the second end of the second switch tube Q2 is grounded, and the third end of the second switch tube Q2 is connected to the second input end of the control circuit 3; the first capacitor C1 is connected in parallel with the second switch tube Q2; the input end of the hysteresis comparator A is connected to the first end of the first capacitor C1, and the output end of the hysteresis comparator A is connected to the third input end of the control circuit 3.

[0044] Specifically, the first capacitor C1 is a sampling capacitor, which is used to maintain the stability of the input signal during the analog-to-digital conversion process, that is, the voltage across the power device to be tested, so as to better monitor the voltage. The first end of the first resistor R1 is connected to the second end of the first switch tube Q1, and the second end of the first resistor R1 is connected to the first end of the second switch tube Q2, which is mainly used to reduce the static loss of the monitoring circuit. The first capacitor C1 and the first resistor R1 form an RC circuit, and the blanking time refers to the time interval set to eliminate signal spikes or interference, and the blanking time is determined by the RC circuit. When the power device to be tested 5 is turned off, the monitoring function of the power device to be tested is not needed at this time, and the control circuit 3 simultaneously controls the first switch tube Q1 and the second switch tube Q2 to be in the off state; when the power device to be tested 5 is desaturated, the voltage across the power device to be tested will increase abnormally, the monitoring circuit is turned on, and the power supply VCC charges the first capacitor C1 until the trigger threshold of the hysteresis comparator A is reached, and the output level of the hysteresis comparator A is flipped. Two thresholds can be calculated from the threshold expression of the hysteresis comparator A, corresponding to the upper threshold and the lower threshold. When the upper threshold is exceeded or the lower threshold is lower than the lower threshold, the output level of the hysteresis comparator A flips. Exemplarily, the calculation method of the upper threshold and the lower threshold is explained below: Figure 3 is an equivalent circuit diagram of a hysteresis comparator in a desaturation fault monitoring device provided by an embodiment of the present invention, with reference to Figure 3 :

[0045] The threshold voltage calculation is mainly to calculate the voltage of U+. It is obvious that the resistor voltage division method is used to calculate:

[0046] When the output U0 is high, the output terminal is pulled up to 15V. Assuming the resistor R a is 20kΩ, the resistor R b is 10kΩ, the resistor R c is 10kΩ, the resistor R d is 10kΩ, the resistor R b and resistor R c Then connect in series with resistor R a In parallel, the equivalent resistance R is: R = (R b +R c )*R a / ((R b +R c )+R a )=(10+10)*20 / ((10+10)+20)=10kΩ. Then the voltage of U+ can be calculated based on the resistance voltage division: U+=(R a / (R+R a ))*15V=(10 / (10+10))*15=7.5V.

[0047] The voltage calculated at this time is the upper threshold voltage of U+: that is, U th =U+=7.5V.

[0048] Figure 4 is an equivalent circuit diagram of a hysteresis comparator in another desaturation fault monitoring device provided by an embodiment of the present invention, with reference to Figure 4 :

[0049] When the output U0 is low, the output is grounded and the resistor R e is 20kΩ, the resistor R f is 10kΩ, the resistor R g is 10kΩ, the resistor R h is 10kΩ, the resistor R f and resistor R h Parallel connection, the resistance after parallel connection is R = (R f *R h ) / (R f +R h )=100 / 20=5kΩ. Then the voltage of U+ can be calculated based on the resistance voltage division: U+=(R / (R+R e))*15V=(5 / (5+20))*15=3V. The voltage U+ calculated at this time is the lower threshold voltage, that is, U tl =U+=3V. Through the above calculation, the upper threshold voltage U of the hysteresis comparator A is th =7.5V, U tl =3V.

[0050] Optionally, the monitoring circuit also includes a second resistor R2 and a third resistor R3; the first end of the second resistor R2 is connected to the second end of the first resistor R1, and the second end of the second resistor R2 is connected to the first end of the first capacitor C1; the first end of the third resistor R3 is connected to the second end of the second resistor R2, and the second end of the third resistor R3 is connected to the first end of the second switch tube Q2.

[0051] Specifically, the first end of the third resistor R3 is connected to the second end of the second resistor R2, and the second end of the third resistor R3 is connected to the first end of the second switch tube Q2. The third resistor R3 and the second switch tube Q2 constitute a fast discharge branch of the first capacitor C1, which is mainly used to quickly release the storage capacitance in the first capacitor C1, thereby avoiding startup delays or other potential problems caused by residual charge in the first capacitor C1, thereby ensuring the reliability and stability of the electronic equipment. When the power device to be tested is turned off, the second switch tube Q2 is turned on to suppress the interference caused by the rapid change of the bypass voltage.

[0052] Optional, continue to refer to Figure 2 The monitoring circuit further includes a first diode D1; a first end of the first diode D1 is connected to a first end of the first capacitor C1; and a second end of the first diode D1 is grounded.

[0053] Specifically, the first end of the first diode D1 is connected to the first end of the first capacitor C1, and the second end of the first diode D1 is grounded, which is mainly used to prevent the voltage of the first capacitor C1 from being too high, thereby damaging the first capacitor C1 and the hysteresis comparator A. The control circuit 3 simultaneously controls the first switch tube Q1 and the second switch tube Q2 to be in an on state. When the power device to be tested works normally, the voltage at both ends is very low, and discharge is performed through the fast discharge branch (i.e., the circuit composed of the third resistor R3 and the second switch tube Q2). The first diode D1 prevents the voltage of the fast discharge branch from being too high to damage the first capacitor C1.

[0054] Optional, continue to refer to Figure 2The monitoring circuit also includes a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, and a ninth resistor R9; the first positive terminal of the hysteresis comparator A is connected to the first end of the eighth resistor R8, the second end of the eighth resistor R8 is connected to the first end of the ninth resistor R9, and the second end of the ninth resistor R9 is connected to the third input end of the control circuit 3; the first negative terminal of the hysteresis comparator A is grounded through the fifth resistor R5; the second positive terminal of the hysteresis comparator A is grounded, and the second negative terminal of the hysteresis comparator A is connected to the output end of the hysteresis comparator A; the sixth resistor R6 is connected in series with the seventh resistor R7, the first end of the sixth resistor R6 is connected to the first negative terminal of the hysteresis comparator A, and the second end of the seventh resistor R7 is connected to the first end of the ninth resistor R9; the first end of the fourth resistor R4 is connected to the second end of the second resistor R2, and the second end of the fourth resistor R4 is connected to the first positive terminal of the hysteresis comparator A.

[0055] Specifically, the monitoring circuit adopts a hysteresis comparator A to avoid the influence of interference on the protection signal. When a desaturation fault occurs in the power device to be tested, when the threshold voltage range of the hysteresis comparator A is reached, the hysteresis comparator A converts a high level to a low level or converts a low level to a high level.

[0056] Optional, continue to refer to Figure 2 The monitoring circuit further includes a second diode D2; a first end of the second diode D2 is connected to the first electrode of the power device 5 to be measured, and a second end of the second diode D2 is connected to the second end of the first resistor R1.

[0057] Specifically, the first end of the second diode D2 is connected to the first electrode of the power device 5 to be tested, and the second end of the second diode D2 is connected to the second end of the first resistor R1 to protect the components in the circuit from being damaged by reverse voltage, ensuring stable and safe operation of the circuit.

[0058] Figure 5 is a circuit schematic diagram of another desaturation fault monitoring device provided by an embodiment of the present invention, referring to Figure 5 Optionally, the control circuit 3 includes a control module 31, a third switch tube Q3 and a fourth switch tube Q4; the first output end of the control module 31 is connected to the third end of the third switch tube Q3, and the second output end of the control module 31 is connected to the third end of the fourth switch tube Q4; the first end of the third switch tube Q3 is connected to the positive voltage end VCC2 of the control circuit 3, and the second end of the third switch tube Q3 is connected to the first end of the fourth switch tube Q4; the second end of the fourth switch tube Q4 is connected to the negative voltage end VEE of the control circuit 3.

[0059] Specifically, the control circuit 3 includes a control module 31, a third switch tube Q3 and a fourth switch tube Q4; when the third switch tube Q3 is turned on, the positive voltage drive makes the power device 5 under test turn on normally; when the fourth switch tube Q4 is turned on, the power device 5 under test is turned off.

[0060] Optional, continue to refer to Figure 5 The first electrode of the power device 5 to be tested is connected to the input end of the monitoring circuit, and the second electrode of the power device 5 to be tested is connected to the control end of the control circuit 3.

[0061] Specifically, when the power device to be tested 5 is turned off, the monitoring function of the power device to be tested is not required, and the control circuit 3 simultaneously controls the first switch tube Q1 and the second switch tube Q2 to be in the off state.

[0062] Optionally, the power device 5 to be tested includes a silicon carbide power device.

[0063] According to the same inventive concept, an embodiment of the present invention provides a vehicle, comprising the monitoring device for desaturation fault described in any of the above-mentioned embodiments of the invention.

[0064] A vehicle provided by an embodiment of the present invention can achieve the same technical effect as a desaturation fault monitoring device provided by the above-mentioned embodiment of the invention, which will not be described in detail here.

[0065] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A monitoring device for desaturation fault, characterized in that: Including power supply circuit, monitoring circuit, control circuit and drive circuit; The output end of the power supply circuit is connected to the first input end of the control circuit, and the power supply circuit is used to provide electrical energy to the control circuit; The first output terminal of the control circuit is connected to the monitoring circuit, and the second output terminal of the control circuit is connected to the driving circuit; The first output terminal of the monitoring circuit is connected to the control circuit, and the output terminal of the driving circuit is connected to the power device to be tested; The monitoring circuit is used to transmit fault information to the control circuit when detecting a desaturation fault in the power device under test, and the control circuit generates a drive signal based on the fault information to control the drive circuit to shut down the power device under test.

2. The desaturation fault monitoring device according to claim 1, characterized in that: The monitoring circuit includes a first switch tube, a second switch tube, a first resistor, a first capacitor and a hysteresis comparator; The first end of the first switch tube is connected to the power supply, the second end of the first switch tube is connected to the first end of the first resistor; the third end of the first switch tube is connected to the first input end of the control circuit; The first end of the second switch tube is connected to the second end of the first resistor, the second end of the second switch tube is grounded, and the third end of the second switch tube is connected to the second input end of the control circuit; The first capacitor is connected in parallel with the second switch tube; the input end of the hysteresis comparator is connected to the first end of the first capacitor, and the output end of the hysteresis comparator is connected to the third input end of the control circuit.

3. The desaturation fault monitoring device according to claim 2, characterized in that: The monitoring circuit also includes a second resistor and a third resistor; The first end of the second resistor is connected to the second end of the first resistor, and the second end of the second resistor is connected to the first end of the first capacitor; the first end of the third resistor is connected to the second end of the second resistor, and the second end of the third resistor is connected to the first end of the second switch tube.

4. The desaturation fault monitoring device according to claim 2, characterized in that: The monitoring circuit also includes a first diode; A first end of the first diode is connected to a first end of the first capacitor; and a second end of the first diode is grounded.

5. The desaturation fault monitoring device according to claim 2, characterized in that: The monitoring circuit further includes a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, and a ninth resistor; The first positive terminal of the hysteresis comparator is connected to the first end of the eighth resistor, the second end of the eighth resistor is connected to the first end of the ninth resistor, and the second end of the ninth resistor is connected to the third input end of the control circuit; the first negative terminal of the hysteresis comparator is grounded through the fifth resistor; The second positive terminal of the hysteresis comparator is grounded, and the second negative terminal of the hysteresis comparator is connected to the output terminal of the hysteresis comparator; The sixth resistor is connected in series with the seventh resistor, the first end of the sixth resistor is connected to the first negative terminal of the hysteresis comparator, and the second end of the seventh resistor is connected to the first end of the ninth resistor; the first end of the fourth resistor is connected to the second end of the second resistor, and the second end of the fourth resistor is connected to the first positive terminal of the hysteresis comparator.

6. The desaturation fault monitoring device according to claim 2, characterized in that: The monitoring circuit also includes a second diode; The first end of the second diode is connected to the first electrode of the power device to be tested, and the second end of the second diode is connected to the second end of the first resistor.

7. The desaturation fault monitoring device according to claim 1, characterized in that: The control circuit includes a control module, a third switch tube and a fourth switch tube; The first output end of the control module is connected to the third end of the third switch tube, and the second output end of the control module is connected to the third end of the fourth switch tube; The first end of the third switch tube is connected to the positive voltage end, the second end of the third switch tube is connected to the first end of the fourth switch tube; the second end of the fourth switch tube is connected to the negative voltage end.

8. The desaturation fault monitoring device according to claim 1, characterized in that: The first electrode of the power device to be tested is connected to the input end of the monitoring circuit, and the second electrode of the power device to be tested is connected to the control end of the control circuit.

9. The desaturation fault monitoring device according to claim 7, characterized in that: The power device to be tested includes a silicon carbide power device.

10. A vehicle, characterized in that: A monitoring device for desaturation fault comprising the device described in any one of claims 1 to 9.

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