A silicon carbide short circuit protection circuit

Abstract

The utility model belongs to power semiconductor device technical field discloses a silicon carbide short circuit protection circuit, including desaturation circuit, temperature detection circuit and singlechip, the desaturation circuit includes port VDC, the port VDC connects the negative end of diode D2 and the drain of MOS tube Q1, the gate of MOS tube Q1 connects singlechip, the positive end of diode D2 connects the negative end of diode D1, the positive end of diode D1 connects one end of resistance R1 and one end of resistance R2, the other end of resistance R1 connects port VCC, the other end of resistance R2 connects the negative end of stabilivolt Z1, one end of resistance R3, one end of capacitor CB1 and the pin 3 of comparator A1. The utility model has the beneficial effects: realize accurate short circuit protection in full temperature range, significantly improve the reliability of SiC device under high temperature and high noise scene such as new energy, electric automobile etc.

Description

Technical Field

[0001] This utility model relates to the field of power semiconductor device technology, and in particular to a silicon carbide short-circuit protection circuit. Background Technology

[0002] Silicon carbide (SiC) MOSFETs are widely used in new energy vehicles, photovoltaic inverters, and other fields due to their high voltage withstand capability, low on-resistance, and high-frequency characteristics. However, the intrinsic properties of SiC materials limit their short-circuit withstand time to only about 2μs, far lower than the 5-10μs of traditional silicon-based IGBTs. Existing short-circuit protection schemes mostly employ fixed-threshold desaturation (DESAT) detection technology, judging short-circuit faults by monitoring sudden changes in drain-source voltage (VDS). However, in practical applications, it has been found that changes in device junction temperature significantly affect the VDS characteristic curve. Increased on-resistance at high temperatures leads to a rise in VDS during normal operation, while the peak short-circuit current is even higher at low temperatures. Traditional fixed-threshold protection strategies are prone to false triggering in high-temperature environments or delayed response in low-temperature environments, reducing system reliability.

[0003] Therefore, it is necessary to provide a silicon carbide short-circuit protection circuit that can achieve accurate protection across the entire temperature range by adjusting the desaturation detection threshold through real-time monitoring of the junction temperature. Utility Model Content

[0004] This utility model discloses a silicon carbide short-circuit protection circuit, which relates to power semiconductor device protection technology. Specifically, it relates to a short-circuit protection circuit for silicon carbide MOSFETs. By adding a temperature detection module to the traditional desaturation (DESAT) detection circuit, the DESAT comparison threshold is dynamically adjusted to solve the problem of protection failure or false triggering caused by junction temperature changes. It can effectively solve the technical problems involved in the background art.

[0005] To achieve the above objectives, the technical solution of this utility model is as follows:

[0006] A silicon carbide short-circuit protection circuit includes a desaturation circuit, a temperature detection circuit, and a microcontroller;

[0007] The desaturation circuit includes a port VDC, which is connected to the negative terminal of diode D2 and the drain of MOSFET Q1. The gate of MOSFET Q1 is connected to a microcontroller. The positive terminal of diode D2 is connected to the negative terminal of diode D1. The positive terminal of diode D1 is connected to one end of resistor R1 and one end of resistor R2. The other end of resistor R1 is connected to port VCC. The other end of resistor R2 is connected to the negative terminal of Zener diode Z1, one end of resistor R3, one end of capacitor CB1, and pin 3 of comparator A1. Pin 2 of comparator A1 is connected to port VREF. Pin 1 of comparator A1 and port VREF are connected to the microcontroller. The other end of capacitor CB1, the other end of resistor R3, the positive terminal of Zener diode Z1, and the source of MOSFET Q1 are connected to port GND1.

[0008] The temperature detection circuit includes a 3.3V port. The 3.3V port is connected to one end of resistor R4. The other end of resistor R4 is connected to one end of the thermistor RT1 and one end of resistor R5. The other end of resistor R5 is connected to one end of capacitor C2, pin 3 of clamping diode D27, and port NTC1. Port NTC1 is connected to a microcontroller. The other end of the thermistor RT1 is connected to the other end of capacitor C2, pin 1 of clamping diode D27, and port GND2. Pin 2 of clamping diode D27 is connected to the 3.3V port.

[0009] The thermistor RT1 is used to detect the temperature of the MOSFET Q1, and the microcontroller controls the switching on and off of the MOSFET Q1 based on the result of the comparator A1.

[0010] This invention discloses a temperature-compensated silicon carbide (SiC) MOSFET short-circuit protection circuit and method, belonging to the field of power semiconductor device protection technology. Addressing the temperature drift problem caused by fixed thresholds in traditional desaturation (DESAT) protection circuits, this solution integrates a temperature detection circuit into the traditional DESAT detection module to monitor the SiC MOSFET junction temperature in real time and dynamically adjust the DESAT comparison threshold. This solves the problems of false triggering caused by increased VDS at high temperatures and missed detection at low temperatures, achieving accurate short-circuit protection across the entire temperature range and significantly improving the reliability of SiC devices in high-temperature and high-noise scenarios such as new energy and electric vehicles.

[0011] As a preferred improvement of this utility model, the port VDC and the port VCC are connected to different power supplies.

[0012] As a preferred improvement of this utility model, the 3.3V port is connected to a 3.3V DC power supply.

[0013] As a preferred improvement of this utility model, the clamping diode D27 is model BAV99.

[0014] As a preferred improvement of this utility model, the microcontroller is an STM32F334R8T6.

[0015] The beneficial effects of this utility model are as follows:

[0016] The temperature detection circuit is integrated into the DESAT detection module to monitor the junction temperature of SiC MOSFET in real time and dynamically adjust the DESAT comparison threshold. This solves the problems of false triggering caused by VDS increase at high temperatures and missed detection at low temperatures, and achieves accurate short-circuit protection across the entire temperature range. This significantly improves the reliability of SiC devices in high-temperature and high-noise scenarios such as new energy and electric vehicles. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0018] Figure 1 This is a schematic diagram of the desaturation circuit of this utility model;

[0019] Figure 2 This is a schematic diagram of the temperature detection circuit structure of this utility model;

[0020] Figure 3 This is a schematic diagram of the microcontroller structure of this utility model;

[0021] Figure 4 for Figure 3 Enlarged illustration Figure 1 ;

[0022] Figure 5 for Figure 3 Enlarged illustration Figure 2 ;

[0023] Figure 6 for Figure 3 Enlarged illustration Figure 3 ;

[0024] Figure 7 for Figure 3 Enlarged illustration Figure 4 ;

[0025] Figure 8 for Figure 3 Enlarged illustration Figure 5 ;

[0026] Figure 9 for Figure 3 Enlarged illustration Figure 6 ;

[0027] Figure 10 for Figure 3 Enlarged illustration Figure 7 ;

[0028] Figure 11 for Figure 3 Enlarged illustration Figure 8 ;

[0029] Figure 12 for Figure 3 Enlarged illustration Figure 9 . Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0032] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0033] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0034] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0035] Please see Figures 1-3 As shown in the figure, this utility model provides a silicon carbide short-circuit protection circuit, including a desaturation circuit, a temperature detection circuit, and a microcontroller. It proposes a dynamic DESAT threshold adjustment method based on temperature compensation, which adjusts the desaturation detection threshold by real-time monitoring of junction temperature to achieve accurate protection across the entire temperature range. The short-circuit protection circuit mainly includes a temperature detection circuit, a microcontroller, and a traditional desaturation circuit. The connection relationship and function of each part are shown in the figure.

[0036] The desaturation circuit includes a port VDC, which is connected to the negative terminal of diode D2 and the drain of MOSFET Q1. The gate of MOSFET Q1 is connected to the microcontroller. The positive terminal of diode D2 is connected to the negative terminal of diode D1. The positive terminal of diode D1 is connected to one end of resistor R1 and one end of resistor R2. The other end of resistor R1 is connected to port VCC. The other end of resistor R2 is connected to the negative terminal of Zener diode Z1, one end of resistor R3, one end of capacitor CB1, and pin 3 of comparator A1. Pin 2 of comparator A1 is connected to port VREF. Pin 1 of comparator A1 and port VREF are connected to the microcontroller. The other end of capacitor CB1, the other end of resistor R3, the positive terminal of Zener diode Z1, and the source of MOSFET Q1 are connected to port GND1. Port VDC and port VCC are connected to different power supplies. Specifically, the drain-source voltage of the silicon carbide MOSFET is monitored in real time and compared with the dynamic DESAT threshold (VREF) output by the microcontroller. When the drain-source voltage exceeds VREF, the desaturation circuit outputs a short-circuit detection signal. Traditional desaturation circuits can employ typical diode clamping, capacitor filtering, and comparator structures to ensure a fast response to short-circuit faults.

[0037] The temperature detection circuit includes a 3.3V port, which is connected to a 3.3V DC power supply. This port is connected to one end of resistor R4. The other end of resistor R4 is connected to one end of the thermistor RT1 and one end of resistor R5. The other end of resistor R5 is connected to one end of capacitor C2, pin 3 of clamping diode D27 (BAV99), and port NTC1. Port NTC1 is connected to a microcontroller. The other end of the thermistor RT1 is connected to the other end of capacitor C2, pin 1 of clamping diode D27, and port GND2. Pin 2 of clamping diode D27 is connected to the 3.3V port. The thermistor RT1 is used to detect the temperature of the MOSFET Q1. Specifically, it is used to measure the temperature of the silicon carbide MOSFET in real time and convert the temperature signal into an electrical signal output. This circuit can use temperature-sensitive elements such as thermistors, thermocouples, or integrated temperature sensors, preferably high-precision, fast-response integrated temperature sensors. The electrical signal output by the temperature detection circuit has a linear or non-linear relationship with the temperature of the silicon carbide MOSFET. After signal conditioning, it is sent to the analog input port of the microcontroller.

[0038] The microcontroller (U1) controls the switching of the MOSFET Q1 based on the result of comparator A1. The microcontroller, model STM32F334R8T6, serves as the control core, receiving the temperature signal output from the temperature detection circuit and converting the analog signal into a digital signal via its internal analog-to-digital converter (ADC). The microcontroller pre-stores a temperature-DESAT threshold mapping table or a temperature-DESAT threshold calculation formula. Based on the converted digital temperature signal, it looks up or calculates the corresponding DESAT threshold (VREF). Then, the microcontroller converts the calculated digital threshold into an analog voltage signal via its internal digital-to-analog converter (DAC) and outputs it to the conventional desaturation circuit.

[0039] The short-circuit protection operation steps are as follows:

[0040] Temperature Sampling: The temperature detection circuit measures the temperature of the silicon carbide MOSFET in real time and converts the temperature signal into an analog electrical signal, which is then output to the microcontroller. The microcontroller samples this analog signal at a certain sampling period and converts it into a digital temperature value through its internal ADC.

[0041] Threshold Calculation: Based on the sampled digital temperature value, the microcontroller queries a pre-stored temperature-DESAT threshold mapping table or uses the temperature-DESAT threshold calculation formula to calculate the corresponding DESAT threshold (VREF) at the current temperature. The temperature-DESAT threshold mapping table can be obtained through actual testing, recording the maximum drain-source voltage of the silicon carbide MOSFET during normal operation and the minimum drain-source voltage during short circuit at different temperatures, thereby determining a suitable DESAT threshold.

[0042] Threshold output: The microcontroller converts the calculated DESAT threshold (VREF) into an analog voltage signal through the internal DAC and outputs it to the traditional desaturation circuit.

[0043] Short circuit detection: Traditional desaturation circuits monitor the drain-source voltage of the silicon carbide MOSFET in real time and compare it with the dynamic DESAT threshold (VREF) output by the microcontroller. When the drain-source voltage exceeds VREF, a short circuit is detected, and the desaturation circuit outputs a short circuit detection signal.

[0044] Protection Action: Upon receiving a short-circuit detection signal, the drive circuit immediately cuts off the drive signal to the silicon carbide MOSFET, causing the MOSFET to turn off rapidly and preventing damage due to excessive short-circuit current. Simultaneously, a fault alarm signal can be set to notify the system to take appropriate action.

[0045] The program of a microcontroller mainly includes the following parts:

[0046] Initialization: Initialize the microcontroller's peripherals such as ADC, DAC, and timers, and configure parameters such as sampling period and output accuracy.

[0047] Temperature sampling: Start ADC sampling, read the analog signal output by the temperature detection circuit, and convert it into a digital temperature value.

[0048] Threshold calculation: Based on the sampled temperature value, query the temperature-DESAT threshold mapping table to obtain the corresponding DESAT threshold.

[0049] Threshold output: The calculated DESAT threshold is converted into an analog voltage signal by a DAC and output to a conventional desaturation circuit.

[0050] Short circuit monitoring: Continuously monitors the short circuit detection signal output by the traditional desaturation circuit. When a short circuit signal is detected, the protection subroutine is called to cut off the drive signal and trigger a fault alarm.

[0051] Example 1

[0052] Temperature Sampling: The temperature detection circuit measures the temperature of the silicon carbide MOSFET in real time. A thermistor RT1 converts the temperature signal into an analog electrical signal, which is then output to the STM32F334R8T6 microcontroller. The STM32F334R8T6 microcontroller samples the analog signal at a certain sampling period and converts it into a digital temperature value using its internal ADC.

[0053] Threshold Calculation: The STM32F334R8T6 microcontroller calculates the corresponding Desat threshold (VREF) at the current temperature by looking up a pre-stored temperature-DESAT threshold mapping table or using the temperature-DESAT threshold calculation formula based on the sampled digital temperature value. The temperature-DESAT threshold mapping table can be obtained through actual testing, recording the maximum drain-source voltage of the silicon carbide MOSFET during normal operation and the minimum drain-source voltage during short circuit at different temperatures, thereby determining a suitable Desat threshold.

[0054] Threshold output: The STM32F334R8T6 microcontroller converts the calculated DESAT threshold (VREF) into an analog voltage signal through the internal DAC and outputs it to the non-inverting input of the comparator in the traditional desaturation circuit.

[0055] Short circuit detection: Traditional desaturation circuits monitor the drain-source voltage of the silicon carbide MOSFET in real time and compare it with the dynamic DESAT threshold (VREF) output by the microcontroller. When the drain-source voltage exceeds VREF, a short circuit is detected, and the desaturation circuit outputs a short circuit detection signal.

[0056] Protection Action: Upon receiving a short-circuit detection signal, the drive circuit immediately cuts off the drive signal to the silicon carbide MOSFET, causing the MOSFET to turn off rapidly and preventing damage due to excessive short-circuit current. Simultaneously, a fault alarm signal can be set to notify the system to take appropriate action.

[0057] Although the embodiments of this utility model have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for this utility model. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, this utility model is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A silicon carbide short-circuit protection circuit, characterized in that: Includes desaturation circuit, temperature detection circuit, and microcontroller; The desaturation circuit includes a port VDC, which is connected to the negative terminal of diode D2 and the drain of MOSFET Q1. The gate of MOSFET Q1 is connected to a microcontroller. The positive terminal of diode D2 is connected to the negative terminal of diode D1. The positive terminal of diode D1 is connected to one end of resistor R1 and one end of resistor R2. The other end of resistor R1 is connected to port VCC. The other end of resistor R2 is connected to the negative terminal of Zener diode Z1, one end of resistor R3, one end of capacitor CB1, and pin 3 of comparator A1. Pin 2 of comparator A1 is connected to port VREF. Pin 1 of comparator A1 and port VREF are connected to the microcontroller. The other end of capacitor CB1, the other end of resistor R3, the positive terminal of Zener diode Z1, and the source of MOSFET Q1 are connected to port GND1. The temperature detection circuit includes a 3.3V port. The 3.3V port is connected to one end of resistor R4. The other end of resistor R4 is connected to one end of the thermistor RT1 and one end of resistor R5. The other end of resistor R5 is connected to one end of capacitor C2, pin 3 of clamping diode D27, and port NTC1. Port NTC1 is connected to a microcontroller. The other end of the thermistor RT1 is connected to the other end of capacitor C2, pin 1 of clamping diode D27, and port GND2. Pin 2 of clamping diode D27 is connected to the 3.3V port. The thermistor RT1 is used to detect the temperature of the MOSFET Q1, and the microcontroller controls the switching on and off of the MOSFET Q1 based on the result of the comparator A1.

2. The silicon carbide short-circuit protection circuit according to claim 1, characterized in that: The VDC port and the VCC port are connected to different power supplies.

3. The silicon carbide short-circuit protection circuit according to claim 1, characterized in that: The 3.3V port is connected to a 3.3V DC power supply.

4. The silicon carbide short-circuit protection circuit according to claim 1, characterized in that: The clamping diode D27 is model BAV99.

5. A silicon carbide short-circuit protection circuit according to claim 1, characterized in that: The microcontroller model is STM32F334R8T6.

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