SiC MOSFET junction temperature on-line monitoring circuit and method based on turn-on delay integrator

Abstract

The invention belongs to the technical field of state monitoring of power electronic devices, and discloses a SiC MOSFET junction temperature online monitoring circuit and method based on a turn-on delay integrator, and the circuit comprises a grid voltage detection circuit, a power source voltage detection circuit, a comparator circuit, a trigger circuit, an isolation circuit and a high-precision integral holding circuit. The gate voltage detection circuit measures the gate voltage of the scaled SiC MOSFET device and transmits the gate voltage to the comparator circuit; the power source electrode voltage detection circuit measures the scaled SiC MOSFET device power source electrode voltage VL in real time, filters the power source electrode voltage, carries out inverse proportion amplification on the power source electrode voltage through the inverting amplifier, and transmits the power source electrode voltage to the comparator circuit; the comparator circuit compares the grid voltage and the power source voltage with the reference voltage Vref1 of the comparator and the reference voltage Vref2 of the comparator respectively, outputs two pulse comparison signals V1 and V2 respectively, and then transmits the two pulse comparison output signals to the trigger circuit. According to the invention, when a plurality of SiC MOFET chips are connected in parallel, the highest junction temperature of the chips can be measured, which is more beneficial to online evaluation of the states of power electronic equipment and devices.

Description

Technical Field

[0001] The present invention belongs to but is not limited to the technical field of power electronic device state monitoring, and in particular relates to a SiC MOSFET junction temperature online monitoring circuit and method based on an on-delay integrator. Background Art

[0002] Compared with Si IGBT, silicon carbide-metal oxide field effect transistor (SiC MOSFET) has lower on-resistance, higher switching speed, higher breakdown electric field and higher high temperature resistance, and has very obvious advantages in improving the performance of power electronic converters. The reliable operation of power electronic converters is directly determined by power devices. Due to the different thermal expansion coefficients of materials in power semiconductor modules, temperature changes will cause mechanical stress. Repeated thermal cycles will eventually lead to cracks in chip solder joints and bonding wire shedding, which will endanger the normal operation of power electronic equipment and SiC MOSFET. SiC MOSFET has a small chip area, high current density, and poor heat dissipation capacity. It is more likely to cause problems such as excessive junction temperature and large fluctuations in actual operation. Statistics show that more than 50% of equipment and device damage is caused by overheating and fluctuations in device junction temperature. Therefore, online measurement or estimation of SiC MOSFET chip junction temperature is crucial to predict the remaining service life of equipment and devices.

[0003] The existing technology mainly uses the thermosensitive electrical parameters of SiC MOSFET to measure or estimate the chip junction temperature online. Common thermosensitive electrical parameters mainly include the on-state voltage drop, threshold voltage, turn-on delay and turn-off delay of SiC MOSFET. The research on the junction temperature online monitoring method based on the on-state voltage drop in Si IGBT is relatively mature, so the on-state voltage drop is also often used to monitor the junction temperature of SiC MOSFET online. However, this method still has very obvious limitations when used for SiC MOSFET. First, the manufacturing process of SiC MOSFET is not yet mature, and its device aging phenomenon is relatively obvious, which causes its on-resistance to drift, thereby affecting the measurement of the on-state voltage drop. The on-state voltage drop measurement is also affected by the changes in actual operating conditions. When the load current is small, its measurement accuracy is extremely low and cannot even be used to estimate the chip junction temperature. In addition, since the actual operation requires the use of multiple chips in parallel packaging as a power semiconductor module to increase the power, the junction temperature calculated using the on-state voltage drop measurement does not have a clear physical meaning, that is, it is impossible to determine whether the obtained junction temperature is the average junction temperature of multiple chips, or the highest or lowest junction temperature. In addition, package aging such as chip solder joint cracks and bond wire shedding will also affect the measurement of on-state voltage drop. It is difficult to distinguish the effects of device aging and package aging during actual measurement. Although the junction temperature monitoring method based on threshold voltage, turn-on delay and turn-off delay is not affected by package aging, due to the fast switching speed of SiC MOSFET, it is difficult to accurately measure the above parameters with existing technology. Even if accurate measurement can be achieved, the above parameters change little with junction temperature, and the junction temperature measurement accuracy cannot meet the requirements.

[0004] Based on the above analysis, there is an urgent need for an online monitoring circuit and method for SiC MOSFET junction temperature to perform online evaluation of power electronic equipment and device status. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a SiC MOSFET junction temperature online monitoring circuit and method based on an open-delay integrator, so as to solve the problems of low measurement accuracy of the existing junction temperature online monitoring technology and the measurement accuracy being easily affected by load size changes and package aging.

[0006] The present invention is implemented as follows: a SiC MOSFET junction temperature online monitoring circuit based on an open-delay integrator, the circuit comprising: a gate voltage detection circuit, a power source voltage detection circuit, a comparator circuit, a trigger circuit, an isolation circuit and a high-precision integral holding circuit;

[0007] The gate voltage detection circuit measures the scaled gate voltage V of the SiC MOSFET device in real time through a voltage follower 1. gs, the gate voltage is filtered and transmitted to the comparator circuit; the power source voltage detection circuit measures the scaled power source voltage V of the SiC MOSFET device in real time through the voltage follower 2 L , the power source voltage is filtered and amplified inversely by an inverting amplifier, and then transmitted to a comparator circuit; the comparator circuit compares the gate voltage and the power source voltage with the reference voltage V of comparator 1 respectively ref1 and the reference voltage V of comparator 2 ref2 Compare and output two pulse comparison signals V 1 and V 2 , and then transmit the two pulse comparison output signals to the trigger circuit; the trigger circuit receives the pulse comparison output signal and generates an on pulse signal V related to the on delay size of the SiC MOSFET 3 , turn on the pulse signal V 3 The width is T on,dyn This width can be adjusted by adjusting the size of the filter capacitor of the gate voltage detection circuit; the isolation circuit is responsible for receiving the pulse signal sent by the trigger circuit and transmitting the opening pulse signal to the high-precision integration and holding circuit.

[0008] Furthermore, the high-precision integral holding circuit is composed of a resistor R 1 and R 2 , capacitor C 1 、Diode D 1 And switch tube S 1 It is responsible for the pulse width T on,dyn The turn-on pulse signal V 3 Integrate on a time scale to achieve the turn-on pulse signal V 3 To the integrated voltage signal V 4 The conversion is achieved by measuring the integrated voltage signal V 4 The online measurement of SiC MOSFET junction temperature can be realized.

[0009] Furthermore, the reference voltage V of the comparator 1 ref1 The reference voltage V of the comparator 2 is usually in the range of negative hundreds of mV to 0V. ref2 Usually the value ranges from 0V to several hundred mV. The pulse width T of the on pulse signal on,dyn Generally it is from a few ns to tens of ns.

[0010] Furthermore, the design of the high-precision integral holding circuit requires the selection of a diode D with a small leakage current. 1 And switch tube S 1 , otherwise it will affect the measurement accuracy of the SiC MOSFET junction temperature online monitoring circuit.

[0011] Another object of the present invention is to provide a method for online monitoring of SiC MOSFET junction temperature based on an on-delay integrator based on the on-delay integrator based SiC MOSFET junction temperature online monitoring circuit, the method specifically comprising:

[0012] 1) Step 1: Place the SiC MOSFET on a heating table and heat the SiC MOSFET to a specified junction temperature;

[0013] 2) Step 2: Perform a double pulse test on the SiC MOSFET at a given bus voltage to obtain the integrated voltage signal V at the chip temperature. 4 Since the magnitude of the integrated voltage signal is independent of the operating conditions, there is no need to adjust the integrated voltage signal V at different load currents. 4 Perform calibration;

[0014] 3) Step 3: Change the temperature of the heating stage and repeat step 2 to obtain the integrated voltage signal V at different chip temperatures. 4 , the integrated voltage signal V can be obtained by least squares linear regression 4 Curve that changes with SiC MOSFET chip temperature;

[0015] 4) Step 4: Repeat steps 1 to 3, changing the bus voltage to obtain the integrated voltage signal V at different bus voltages. 4 The curve of the change with the temperature of SiC MOSFET chip. When the fluctuation range of the system bus voltage is small, the influence of the bus voltage on the measurement accuracy of the junction temperature online monitoring circuit can be ignored, so the fourth step can be omitted; after obtaining the integrated voltage signal V 4 After the SiC MOSFET chip temperature calibration curve is obtained, the integrated voltage signal V after each turn-on of the SiC MOSFET can be calculated based on the calibration curve and the integrated voltage signal V after each turn-on of the SiC MOSFET. 4 To monitor the junction temperature of SiC MOSFET online.

[0016] Another object of the present invention is to provide a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the SiC MOSFET junction temperature online monitoring method based on the turn-on delay integrator.

[0017] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor executes the steps of the method for online monitoring of SiC MOSFET junction temperature based on turning on a delay integrator.

[0018] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0019] First, the circuit provided by the present invention has low cost, simple structure, fast response speed, and is easy to be integrated into the SiCMOSFET driving circuit. The proposed junction temperature online monitoring method is not affected by load size and package aging, which enhances the applicability of the present invention for online monitoring of junction temperature of SiC MOSFET. A method that can greatly improve the accuracy of junction temperature measurement is proposed. The proposed method does not need to reduce the switching speed of SiC MOSFET to achieve accurate measurement of thermistor parameters and will not interfere with the normal operation of the device. The proposed junction temperature online monitoring method has a clearer physical meaning in a multi-chip parallel structure. The proposed method can measure the highest junction temperature of the chip when multiple SiC MOFET chips are connected in parallel, which is more conducive to online evaluation of power electronic equipment and device status.

[0020] 1) The turn-on delay of SiC MOSFET is not related to the load current, chip solder joint cracks, bonding wire shedding and other packaging aging effects. Therefore, the SiC MOSFET junction temperature online monitoring circuit and method based on the turn-on delay integrator proposed in the present invention is not affected by load changes and packaging aging.

[0021] 2) Regarding the improvement of measurement accuracy, the present invention proposes a method for converting the turn-on delay time signal into an integrated voltage signal through a high-precision integration circuit, thereby achieving a significant improvement in the junction temperature measurement accuracy.

[0022] 3) The physical meaning of the integrated voltage signal measured when multiple SiC MOSFET chips are connected in parallel. Since the turn-on delay of SiC MOSFET is negatively correlated with the chip temperature, when multiple SiC MOSFET chips are connected in parallel, the method proposed in the present invention will measure the SiC MOSFET chip that is turned on the earliest. Therefore, the method proposed in the present invention can measure the highest junction temperature of the chip when multiple SiC MOFET chips are connected in parallel, which has a clearer physical meaning.

[0023] Second, the technical solution of the present invention solves the technical problems that people have been eager to solve but have never been able to solve successfully:

[0024] The traditional method believes that the turn-on speed of SiC MOSFET is very fast and the turn-on delay does not change significantly with the chip junction temperature. Only by significantly reducing the turn-on speed of SiC MOSFET can the turn-on delay be accurately measured, and then the chip junction temperature of SiC MOSFET is estimated based on the measured turn-on delay. The method proposed in the present invention solves this problem. Under the premise of not reducing the turn-on speed of SiC MOSFET, an online monitoring method of SiC MOSFET junction temperature based on turn-on delay integrator is proposed. The method estimates the chip junction temperature of SiC MOSFET by measuring the integrated voltage signal V4, and realizes high-precision online monitoring of SiC MOSFET chip junction temperature. In addition, the proposed method is not affected by the load current and is suitable for industrial applications.

[0025] Third, in existing SiC MOSFET power device applications, device junction temperature monitoring has always been a key issue affecting system reliability and safety. Traditional temperature monitoring methods usually rely on external sensors and cannot accurately reflect changes in SiC MOSFET internal junction temperature in real time, causing the device to overheat, degrade in performance, or even fail when operating at high power. In addition, when detecting junction temperature, existing technologies have problems such as slow response speed, insufficient measurement accuracy, and inability to reflect dynamic characteristics such as turn-on delay in real time, which limits their application in high-power scenarios.

[0026] The present invention solves the shortcomings of the traditional junction temperature monitoring method through an online monitoring circuit of SiC MOSFET junction temperature based on a turn-on delay integrator. By measuring the dynamic changes of the gate voltage and the source voltage during the turn-on process of the MOSFET, a pulse signal related to the turn-on delay is generated, and the pulse signal is converted into a voltage signal using a high-precision integral holding circuit, thereby realizing accurate monitoring of the junction temperature. This method no longer relies on external sensors, and directly derives the junction temperature by monitoring the switch delay through the circuit, which greatly improves the accuracy and response speed of temperature detection.

[0027] Compared with the prior art, the present invention has significant technical progress. First, the gate voltage and source voltage signal monitoring at the circuit level is used to ensure the real-time and high-precision of junction temperature monitoring. Secondly, the use of the turn-on delay pulse signal as the basis for junction temperature monitoring greatly improves the system's ability to respond to dynamic temperature changes and solves the problem of slow response of traditional methods. In addition, the filtering and integral holding technology in the circuit design effectively reduces external interference and ensures the reliability and accuracy of the monitoring results.

[0028] In power electronics industry applications, the junction temperature online monitoring circuit of the present invention can significantly improve the safety and service life of SiC MOSFET devices. Through real-time monitoring of the junction temperature, the system can adjust the operating state in time to avoid device damage caused by overheating, which is particularly suitable for high-power scenarios such as electric vehicles and photovoltaic inverters. This circuit not only improves the operating efficiency of the equipment, but also reduces maintenance costs and downtime, providing higher safety and economic benefits for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of online monitoring of SiC MOSFET junction temperature based on an on-time integrator provided by an embodiment of the present invention;

[0030] Figure 2 It is the circuit working principle waveform provided by the embodiment of the present invention;

[0031] Figure 3 This is the implementation process of the SiC MOSFET junction temperature online monitoring method provided by the embodiment of the present invention;

[0032] Figure 4 is the turn-on pulse signal V at different junction temperatures provided by the embodiment of the present invention 3 And the integrated voltage signal V 4 The waveform of

[0033] Figure 5 is the SiC MOSFET chip junction temperature and integrated voltage signal V obtained by least squares linear regression provided by the embodiment of the present invention 4 The fitting curve between

[0034] Figure 6 is a thermal imager image provided by an embodiment of the present invention;

[0035] Figure 7 is the measured integrated voltage signal V provided by the embodiment of the present invention 4 and SiC MOSFET chip junction temperature;

[0036] Figure 8 It is a Buck circuit continuous experiment platform provided by an embodiment of the present invention;

[0037] Fig. 9 is a thermal imager image under steady-state conditions provided by an embodiment of the present invention;

[0038] Fig.10 is the measured integrated voltage signal V provided by the embodiment of the present invention 4 and SiC MOSFET chip junction temperature.

[0039] Fig.11This is a diagram of experimental junction temperature measurement error data provided by an embodiment of the present invention.

[0040] Fig.12 This is a SiC MOSFET device aging compensation measure provided by an embodiment of the present invention; DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0042] like Figure 1 As shown, an embodiment of the present invention provides a SiC MOSFET junction temperature online monitoring circuit based on an open-delay integrator, the circuit comprising: a gate voltage detection circuit, a power source voltage detection circuit, a comparator circuit, a trigger circuit, an isolation circuit and a high-precision integral holding circuit;

[0043] The gate voltage detection circuit measures the scaled gate voltage V of the SiC MOSFET device in real time through a voltage follower 1. gs , the gate voltage is filtered and transmitted to the comparator circuit; the power source voltage detection circuit measures the scaled power source voltage V of the SiC MOSFET device in real time through the voltage follower 2 L , the power source voltage is filtered and amplified inversely by an inverting amplifier, and then transmitted to a comparator circuit; the comparator circuit compares the gate voltage and the power source voltage with the reference voltage V of comparator 1 respectively ref1 and the reference voltage V of comparator 2 ref2 Compare and output two pulse comparison signals V 1 and V 2 , and then transmit the two pulse comparison output signals to the trigger circuit; the trigger circuit receives the pulse comparison output signal and generates an on pulse signal V related to the on delay size of the SiC MOSFET 3 , turn on the pulse signal V 3 The width is T on,dyn This width can be adjusted by adjusting the size of the filter capacitor of the gate voltage detection circuit; the isolation circuit is responsible for receiving the pulse signal sent by the trigger circuit and transmitting the opening pulse signal to the high-precision integration and holding circuit.

[0044] The high-precision integral holding circuit is composed of a resistor R 1 and R 2 , capacitor C 1 、Diode D 1 And switch tube S 1 It is responsible for the pulse width Ton,dyn The turn-on pulse signal V 3 Integrate on a time scale to achieve the turn-on pulse signal V 3 To the integrated voltage signal V 4 The conversion is achieved by measuring the integrated voltage signal V 4 The online measurement of SiC MOSFET junction temperature can be realized.

[0045] The reference voltage V of the comparator 1 ref1 The reference voltage V of the comparator 2 is usually in the range of negative hundreds of mV to 0V. ref2 Usually the value ranges from 0V to several hundred mV. The pulse width T of the on pulse signal on,dyn Generally it is from a few ns to tens of ns.

[0046] The design of the high-precision integral holding circuit requires the selection of a diode D with a small leakage current. 1 And switch tube S 1 , otherwise it will affect the measurement accuracy of the SiC MOSFET junction temperature online monitoring circuit.

[0047] The circuit works as follows: Figure 2 As shown, in this case, the reference voltage V ref1 The value is 0V, the reference voltage V ref2 The value is 200mV, and the pulse width of the open pulse signal is T on,dyn Adjusted to vary from 8.7ns to 22.4ns.

[0048] One of the key points of this circuit is the gate voltage detection circuit and the power source voltage detection circuit. The gate voltage detection circuit monitors the gate voltage Vgs of the SiC MOSFET device in real time through the voltage follower 1, scales and filters it, and transmits it to the comparator circuit. The power source voltage detection circuit measures the source voltage VL in real time through the voltage follower 2. After filtering, it is inversely amplified by the inverting amplifier to ensure accurate processing of the voltage signal. After these processing, the two voltage signals are provided to the comparator circuit for comparison. In this way, the circuit can capture and track the dynamic working state of the MOSFET device.

[0049] The comparator circuit receives signals from the gate voltage detection circuit and the source voltage detection circuit, and compares the gate voltage with the reference voltage Vref1 and the source voltage with the reference voltage Vref2. After comparison, the two pulse signals V1 and V2 are transmitted to the trigger circuit respectively. After receiving these comparison signals, the trigger circuit generates a turn-on pulse signal V3 related to the turn-on delay of the SiCMOSFET, with a pulse width of Ton,dyn. The pulse width can be adjusted by adjusting the size of the filter capacitor, thereby achieving accurate measurement of different turn-on delays. This process provides important time parameters for subsequent junction temperature monitoring.

[0050] The turn-on pulse signal V3 generated by the trigger circuit needs to be processed by the isolation circuit. The isolation circuit ensures the stable transmission of the pulse signal, avoids noise interference, and transmits the signal to the high-precision integration and holding circuit. The isolation circuit is designed to avoid signal attenuation and errors that occur during high-frequency signal transmission and ensure the integrity of the signal during junction temperature measurement. The isolation circuit not only protects the stable operation of the high-precision integration circuit, but also ensures the correct transmission of the pulse signal.

[0051] The high-precision integral holding circuit is responsible for converting the pulse signal V3 into an integral voltage signal V4. The circuit consists of resistors R1, R2, capacitor C1, diode D1 and switch tube S1. It uses an open pulse signal with a pulse width of Ton,dyn to generate a voltage signal V4 proportional to the junction temperature of the SiC MOSFET through the resistor-capacitor integration method. This signal can be directly measured and used for junction temperature monitoring. In order to ensure the accuracy of the measurement, the diode D1 and switch tube S1 in the integral holding circuit need to have a lower leakage current to reduce signal loss. Through this integration operation, real-time and online monitoring of the SiC MOSFET junction temperature is achieved, thereby ensuring the stable operation of the equipment under high power conditions.

[0052] In view of the influence of SiC MOSFET device aging, the present invention also provides a junction temperature monitoring compensation calibration method based on thermocouples, the steps of which are as follows: Fig.12As shown. First, before the device starts running, the ambient temperature at this time is obtained by measuring the voltage across the thermocouple on the SiC MOSFET substrate. Then, after the device starts running, the integrated voltage signal V4 obtained by the SiC MOSFET in the previous several turn-on processes is measured, and the ambient temperature information obtained by the thermocouple and the SiC MOSFET junction temperature information obtained by the voltage signal V4 are compared. If the difference between the two is large, the controller adjusts the size of the gate voltage detection circuit filter capacitor to adjust the pulse width of the turn-on pulse signal V3. In this way, the aging effect of the SiC MOSFET device can be compensated, so that the junction temperature monitoring circuit can be completely unaffected by the aging of the package and the aging of the device, which greatly improves the stability and accuracy of the proposed method.

[0053] The present invention provides a SiC MOSFET junction temperature monitoring compensation calibration method based on thermocouples, which aims to solve the error problem caused by package aging and device aging in traditional monitoring methods by accurately monitoring and calibrating the junction temperature of MOSFET devices. The main working principle of this method is to use thermocouples to monitor the ambient temperature in real time, and combine the working state of MOSFET to calculate the junction temperature by integrating the voltage signal, so as to perform compensation calibration and improve the accuracy and stability of temperature monitoring.

[0054] Before the device is operated, the voltage across the SiC MOSFET substrate is measured by a thermocouple to obtain the current ambient temperature. Thermocouples can accurately sense the ambient temperature through the voltage changes across them. This step provides a benchmark for subsequent junction temperature monitoring, ensuring effective temperature compensation and calibration in subsequent work.

[0055] After the device is running, as the SiC MOSFET is turned on multiple times, the thermocouple will continue to monitor the ambient temperature. At the same time, during each turn-on process, the system will obtain the integrated voltage signal V4 of the MOSFET by collecting the signal of the gate voltage detection circuit. This integrated voltage signal directly reflects the heat accumulation of the device during the turn-on process and can be used as an important basis for calculating the junction temperature of the device.

[0056] Next, the system compares the ambient temperature measured by the thermocouple with the junction temperature information calculated by the integrated voltage signal V4. If the difference between the two is large, it indicates that the temperature monitoring error caused by device aging or package aging begins to appear, and compensation calibration is required. The specific compensation method is to adjust the size of the filter capacitor in the gate voltage detection circuit through the controller to further correct the pulse width of the turn-on pulse signal V3.

[0057] By adjusting the size of the filter capacitor to correct the pulse width of the pulse signal V3, the error caused by device aging can be effectively eliminated. This is because the filter capacitor will directly affect the response speed of the circuit, and then affect the junction temperature calculation process of the MOSFET. Through this real-time adjustment, it is ensured that the junction temperature monitoring result can reflect the actual temperature state.

[0058] This thermocouple-based compensation calibration method greatly improves the stability and accuracy of junction temperature monitoring. Even in the case of MOSFET device or package aging, the system can still accurately monitor the junction temperature of the device through feedback adjustment, ensuring the safety and reliability of equipment operation.

[0059] like Figure 3 As shown, an embodiment of the present invention provides a SiC MOSFET junction temperature online monitoring method based on a turn-on delay integrator based on the SiC MOSFET junction temperature online monitoring circuit based on a turn-on delay integrator, and the method specifically includes:

[0060] 1) Step 1: Place the SiC MOSFET on a heating table and heat the SiC MOSFET to a specified junction temperature;

[0061] 2) Step 2: Perform a double pulse test on the SiC MOSFET at a given bus voltage to obtain the integrated voltage signal V at the chip temperature. 4 Since the magnitude of the integrated voltage signal is independent of the operating conditions, there is no need to adjust the integrated voltage signal V at different load currents. 4 Perform calibration;

[0062] 3) Step 3: Change the temperature of the heating stage and repeat step 2 to obtain the integrated voltage signal V at different chip temperatures. 4 , the integrated voltage signal V can be obtained by least squares linear regression 4 Curve that changes with SiC MOSFET chip temperature;

[0063] 4) Step 4: Repeat steps 1 to 3, changing the bus voltage to obtain the integrated voltage signal V at different bus voltages. 4 The curve of the change with the temperature of SiC MOSFET chip. When the fluctuation range of the system bus voltage is small, the influence of the bus voltage on the measurement accuracy of the junction temperature online monitoring circuit can be ignored, so the fourth step can be omitted; after obtaining the integrated voltage signal V 4 After the SiC MOSFET chip temperature calibration curve is obtained, the integrated voltage signal V after each turn-on of the SiC MOSFET can be calculated based on the calibration curve and the integrated voltage signal V after each turn-on of the SiC MOSFET. 4 To monitor the junction temperature of SiC MOSFET online.

[0064] In this case, the integrated voltage signal V is implemented for a single SiC MOSFET 4 The integrated voltage signal V is measured at the junction temperature of 25°C, 50°C, 75°C, 100°C, 125°C, and 150°C. 4 , turn-on pulse signal V at different junction temperatures 3 And the integrated voltage signal V 4 The waveform is as Figure 4 As shown in Figure 2, as the junction temperature of the SiC MOSFET chip rises from 25°C to 150°C, the turn-on pulse signal V 3 The pulse width T on,dyn From 22.4ns down to 8.7ns, the range is 13.7ns, and its temperature sensitivity is about 0.11ns / ℃. If the system clock of the counter and controller is used to measure the pulse width T on,dyn The controller clock frequency is usually in the range of 50MHz to 1GHz, and the maximum accuracy of its junction temperature measurement is about 10℃, which makes it difficult to accurately measure the junction temperature of the SiCMOSFET chip. As the junction temperature of the SiCMOSFET chip rises from 25℃ to 150℃, the integrated voltage signal V 4 From 2.456V to 1.072V, the range is 1.384V, and its temperature sensitivity is about 11mV / ℃. If an analog-to-digital conversion chip is used to measure the integrated voltage signal V 4 The sampling accuracy of the analog-to-digital conversion chip can usually reach 1mV, and the maximum junction temperature measurement accuracy is about 0.1℃. According to the above analysis, the SiC MOSFET junction temperature online monitoring method proposed in the present invention can greatly improve the junction temperature measurement accuracy. The SiC MOSFET chip junction temperature and the integrated voltage signal V obtained by the least squares linear regression 4 The fitting curve between Figure 5 shown.

[0065] In order to measure the error of the proposed SiC MOSFET junction temperature online monitoring method, based on Figure 5 The obtained fitting curve was subjected to double pulse test and continuous test experiments to verify the junction temperature measurement accuracy of the proposed method:

[0066] 1) Double pulse test experimental verification: By changing the temperature of the heating stage, the chip junction temperature is controlled at 114.2℃. The thermal imager image is as follows Figure 6 The integrated voltage signal V measured by the proposed method is shown in 4 and the junction temperature of SiC MOSFET chip Figure 7 As shown, the measured integrated voltage is 1.369V, the junction temperature of the SiC MOSFET chip is about 113.6℃, ​​and the junction temperature measurement error is less than 1℃.

[0067] 2) Continuous test experimental verification: Figure 8 The following is the Buck circuit continuous experiment platform built in this case. The thermal imager image under steady-state conditions is as follows: Fig. 9 As shown in the figure, the junction temperature of the SiC MOSFET chip measured by the thermal imager is 98.6℃. The integrated voltage signal V 4 and the junction temperature of SiC MOSFET chip Fig.10 As shown, the measured integrated voltage is 1.648V, the junction temperature of the SiCMOSFET chip is about 96.7℃, and the junction temperature measurement error is less than 2℃.

[0068] Based on the above case results, the feasibility and measurement accuracy of the SiC MOSFET junction temperature online monitoring circuit and method based on the turn-on time integrator proposed in the present invention have been verified. The proposed method can realize high-precision online monitoring of the chip junction temperature of SiC MOSFET.

[0069] An embodiment of the present invention provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method for online monitoring of SiC MOSFET junction temperature based on turning on a delay integrator.

[0070] An embodiment of the present invention provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the processor executes the steps of the method for online monitoring of SiC MOSFET junction temperature based on turning on a delay integrator.

[0071] Example 1: Online monitoring of SiC MOSFET junction temperature for electric vehicle inverters

[0072] In the application of electric vehicle inverters, SiC MOSFET devices are widely used in power conversion due to their efficient switching performance, but under high-frequency switching and high current, the junction temperature of SiC MOSFET will rise rapidly, affecting its reliability and life. Therefore, it is necessary to monitor the junction temperature of SiC MOSFET in real time to ensure the safe operation of the equipment.

[0073] In this embodiment, the SiC MOSFET junction temperature online monitoring circuit based on the turn-on delay integrator is integrated into the power module of the inverter. Through this system, the gate voltage detection circuit and the power source voltage detection circuit obtain the gate voltage Vgs and source voltage VL of the SiC MOSFET in real time, and compare them with the reference voltages Vref1 and Vref2 respectively to generate pulse signals V1 and V2. The trigger circuit generates an open pulse signal V3 based on these two pulse signals, which represents the turn-on delay time Ton,dyn of the SiC MOSFET.

[0074] Subsequently, the turn-on pulse signal V3 is transmitted to the high-precision integral holding circuit, and the integral voltage signal V4 is obtained through the measuring device, which directly reflects the junction temperature change of the SiC MOSFET. By integrating the monitoring circuit in the inverter control system, the online monitoring of the SiC MOSFET junction temperature can be realized. When the junction temperature exceeds the safety threshold, the inverter control system can timely limit the power or shut down the protection to prevent the SiC MOSFET from being damaged due to overheating.

[0075] Example 2: SiC MOSFET junction temperature monitoring in photovoltaic inverters

[0076] The PV inverter is a key device for converting direct current into alternating current. With the application of SiC MOSFET technology, the conversion efficiency of the PV inverter has been significantly improved. However, in high temperature and high power working environments, junction temperature monitoring of SiC MOSFET is essential to ensure its reliability and long-term stable operation.

[0077] In this embodiment, the online monitoring method of SiC MOSFET junction temperature based on the turn-on delay integrator is applied to the photovoltaic inverter. First, the gate voltage detection circuit measures the scaled SiC MOSFET gate voltage Vgs in real time through the voltage follower, and inputs it into the comparator circuit after filtering. The power source voltage detection circuit filters and amplifies the source voltage VL through the inverting amplifier and inputs it into the comparator circuit.

[0078] The comparator circuit compares Vgs with Vref1 and VL with Vref2 respectively to generate pulse signals V1 and V2. The trigger circuit generates a pulse signal V3 representing the turn-on delay time of the SiC MOSFET based on V1 and V2. The width of the pulse signal is Ton,dyn and will be transmitted to the high-precision integral holding circuit. The integral holding circuit integrates and converts the turn-on pulse signal V3 to obtain an integral voltage signal V4, which reflects the junction temperature of the SiC MOSFET in real time.

[0079] During the operation of the photovoltaic inverter, when the junction temperature of the SiC MOSFET reaches a critical value, the inverter control system can automatically adjust the working state according to the junction temperature signal, thereby avoiding overheating and failure of the SiC MOSFET and improving the safety and operating efficiency of the photovoltaic system.

[0080] Example 1: Online monitoring of junction temperature of high-power SiC MOSFET in electric vehicle inverter

[0081] In the electric drive system of electric vehicles, SiC MOSFET, as a core power switching device, is subjected to high power and high temperature working environment. In the inverter module, real-time monitoring of the junction temperature of SiC MOSFET is crucial for the reliable operation of the system. The junction temperature monitoring circuit based on the turn-on delay integrator provided by the present invention is applied to this scenario, and the specific operation is as follows:

[0082] 1. Gate voltage and source voltage detection: The gate voltage detection circuit and the power source voltage detection circuit monitor the gate voltage and source voltage of the MOSFET in real time, respectively, and transmit them to the comparator circuit. After the voltage signal is processed by the filter and amplifier, it accurately reflects the working status of the SiC MOSFET.

[0083] 2. Pulse signal generation and regulation: After the comparator circuit compares the voltage signal with the reference voltage, it generates pulse signals V1 and V2. The trigger circuit generates an open pulse signal V3 based on the pulse signal. Its pulse width Ton,dyn is adjusted by the change of the gate voltage to accurately reflect the open delay.

[0084] 3. Junction temperature measurement: The high-precision integral hold circuit converts the turn-on pulse signal V3 into an integral voltage signal V4. By measuring the size of V4, the junction temperature of the SiC MOSFET can be directly derived. The control system of the electric vehicle monitors the junction temperature of the SiC MOSFET in the inverter in real time through this circuit to prevent the device from overheating and ensure the stability of the system.

[0085] Effect: In practical applications, by real-time monitoring of the junction temperature of SiC MOSFET, the overheating of the device under high power conditions was successfully prevented, the service life of the inverter was extended, and the reliability of the electric vehicle power system was improved.

[0086] Example 2: SiC MOSFET junction temperature monitoring in photovoltaic inverters

[0087] In photovoltaic power generation systems, inverters are usually in a long-term high-power working state. SiC MOSFET is a core switching device, and its junction temperature monitoring is crucial to the operation of the system. The junction temperature monitoring circuit provided by the present invention is applied to photovoltaic inverters, and the specific implementation process is as follows: 1. Voltage detection and pulse signal generation: The gate voltage detection circuit and the power source voltage detection circuit respectively monitor the gate voltage Vgs and source voltage VL of the SiC MOSFET in the photovoltaic inverter in real time. The voltage signal is transmitted to the comparator circuit and generates pulse signals V1 and V2. 2. Turn-on delay pulse signal: After the comparator circuit compares Vgs and VL with the reference voltage Vref, the trigger circuit generates a pulse signal V3 related to the turn-on delay. The width of the pulse signal Ton,dyn is precisely controlled by adjusting the size of the filter capacitor to ensure real-time measurement of the turn-on delay.

[0088] 3. Junction temperature conversion of the integral holding circuit: The high-precision integral holding circuit converts the turn-on pulse signal into a voltage signal V4, through which the junction temperature of the SiC MOSFET can be calculated in real time. The control system of the photovoltaic inverter uses this monitoring result to adjust the system operating parameters in real time to avoid overheating or failure of the SiC MOSFET. Effect: In the application of photovoltaic inverters, by real-time online monitoring of the junction temperature of the SiC MOSFET, device failure caused by long-term high-power operation is prevented, the operating efficiency and stability of the photovoltaic system are improved, and the maintenance and replacement costs of the equipment are reduced.

[0089] It should be noted that the embodiments of the present invention can be implemented by hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated design hardware. It can be understood by a person of ordinary skill in the art that the above-mentioned devices and methods can be implemented using computer executable instructions and / or contained in a processor control code, such as a carrier medium such as a disk, CD or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. Such code is provided on the carrier medium. The device and its modules of the present invention can be implemented by hardware circuits such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc., can also be implemented by software executed by various types of processors, and can also be implemented by a combination of the above-mentioned hardware circuits and software, such as firmware.

[0090] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A SiC MOSFET junction temperature online monitoring circuit based on a turn-on delay integrator, characterized in that: The circuit comprises: a gate voltage detection circuit, a power source voltage detection circuit, a comparator circuit, a trigger circuit, an isolation circuit and a high-precision integral holding circuit; The gate voltage detection circuit measures the scaled gate voltage Vgs of the SiC MOSFET device in real time through the voltage follower 1, and transmits the gate voltage to the comparator circuit after filtering; The power source voltage detection circuit measures the scaled power source voltage VL of the SiC MOSFET device in real time through the voltage follower 2, and filters the power source voltage and transmits it to the comparator circuit after inversely amplifying it by the inverting amplifier; The comparator circuit compares the gate voltage and the power source voltage with the reference voltage Vref1 of comparator 1 and the reference voltage Vref2 of comparator 2, respectively, outputs two pulse comparison signals V1 and V2, and transmits them to the trigger circuit; The trigger circuit receives the pulse comparison output signal and generates an on-pulse signal V3 related to the on-delay size of the SiC MOSFET. The width of the on-pulse signal V3 is Ton,dyn, and the pulse width can be adjusted by adjusting the size of the filter capacitor of the gate voltage detection circuit. The isolation circuit receives the pulse signal sent by the trigger circuit and transmits the signal to the high-precision integration and holding circuit.

2. The SiC MOSFET junction temperature online monitoring circuit based on turn-on delay integrator according to claim 1, characterized in that: A compensation calibration circuit for SiC MOSFET junction temperature monitoring is also provided, the circuit comprising: A thermocouple is mounted on the SiC MOSFET substrate to measure the ambient temperature and generate ambient temperature information through the voltage signal across the thermocouple. An integral voltage detection module, used for generating an integral voltage signal V4 during multiple turn-on processes of the SiC MOSFET; A comparison module, used for comparing the ambient temperature information measured by the thermocouple and the SiC MOSFET junction temperature information calculated by integrating the voltage signal V4; A controller is connected to the comparison module and is used to adjust the filter capacitor in the gate voltage detection circuit according to the difference between the two to control the pulse width of the turn-on pulse signal V3, thereby compensating for the aging effect of the SiC MOSFET device and ensuring the accuracy and stability of junction temperature monitoring.

3. The SiC MOSFET junction temperature online monitoring circuit based on turn-on delay integrator according to claim 1, characterized in that: The high-precision integral holding circuit is composed of resistors R1 and R2, a capacitor C1, a diode D1 and a switch tube S1, and is used to integrate an on-pulse signal V3 with a pulse width of Ton,dyn on a time scale, thereby converting the on-pulse signal V3 into an integrated voltage signal V4, and realizing online measurement of the junction temperature of the SiC MOSFET by measuring the integrated voltage signal V4.

4. The SiC MOSFET junction temperature online monitoring circuit based on turn-on delay integrator according to claim 1, characterized in that: The reference voltage Vref1 of the comparator 1 ranges from negative hundreds of millivolts to 0 volts, the reference voltage Vref2 of the comparator 2 ranges from 0 volts to hundreds of millivolts, and the pulse width Ton,dyn of the on-pulse signal ranges from a few nanoseconds to tens of nanoseconds.

5. The SiC MOSFET junction temperature online monitoring circuit based on turn-on delay integrator according to claim 1, characterized in that: The diode D1 and the switch tube S1 in the high-precision integral holding circuit need to be selected as components with small leakage current to avoid affecting the measurement accuracy of the SiC MOSFET junction temperature online monitoring circuit.

6. The SiC MOSFET junction temperature online monitoring circuit based on turn-on delay integrator according to claim 1, characterized in that: The capacity of the filter capacitors of the gate voltage detection circuit and the power source voltage detection circuit can be adjusted according to the requirements of the pulse width Ton,dyn in practical applications to ensure the stability and accuracy of the turn-on pulse signal V3.

7. A method for online monitoring of SiC MOSFET junction temperature based on turn-on delay integrator, characterized in that: The following steps are involved: 1) The gate voltage Vgs of the SiC MOSFET device is measured in real time through the gate voltage detection circuit, and the measured gate voltage is filtered; 2) The power source voltage VL of the SiC MOSFET device is measured in real time through the power source voltage detection circuit, and the measured power source voltage is filtered and inversely amplified; 3) Compare the filtered gate voltage with the reference voltage Vref1 and output the first pulse signal V1; Compare the filtered power source voltage with the reference voltage Vref2 and output a second pulse signal V2; 4) Generate an on-pulse signal V3 according to the pulse signals V1 and V2, wherein the pulse width Ton,dyn of the on-pulse signal is related to the on-delay of the SiC MOSFET; 5) The turn-on pulse signal V3 is transmitted to a high-precision integral holding circuit, the pulse signal V3 is converted into an integral voltage signal V4 by the integral holding circuit, and the junction temperature of the SiC MOSFET is monitored online by the integral voltage signal.

8. The method for online monitoring junction temperature of SiC MOSFET based on turn-on delay integrator according to claim 7, characterized in that: In the step 5, the integration of the turn-on pulse signal V3 is realized by a high-precision integration and holding circuit, which includes a resistor, a capacitor, a diode and a switch tube. The integration process realizes the conversion of the pulse signal to the integrated voltage signal through the pulse width Ton,dyn; in the step 4, the pulse width Ton,dyn of the turn-on pulse signal V3 can be adjusted by adjusting the capacity of the filter capacitor in the gate voltage detection circuit to ensure the accuracy of the pulse signal width, thereby obtaining a more accurate junction temperature measurement result.

9. The method for online monitoring junction temperature of SiC MOSFET based on turn-on delay integrator according to claim 7, characterized in that: The reference voltage Vref1 in step 3 has a value range of negative several hundred millivolts to 0 volts, and the reference voltage Vref2 has a value range of 0 volts to several hundred millivolts, so as to ensure that the generated pulse signals V1 and V2 can effectively reflect the on-state of the SiC MOSFET; in step 5, a diode and a switch tube with a small leakage current are used to improve the accuracy of the high-precision integral holding circuit, thereby ensuring the stability and accuracy of the junction temperature measurement.

10. The method for online monitoring junction temperature of SiC MOSFET based on turn-on delay integrator according to claim 7, characterized in that: A thermocouple-based SiC MOSFET junction temperature monitoring compensation calibration method is also included, including the following steps: Before the equipment is operated, the ambient temperature is obtained by measuring the voltage across the thermocouple on the SiC MOSFET substrate; After the device is running, measure the integrated voltage signal V4 obtained during multiple turn-on processes of the SiC MOSFET; Compare the ambient temperature information measured by the thermocouple with the SiC MOSFET junction temperature information calculated by integrating the voltage signal V4; If there is a large difference between the two, the controller adjusts the filter capacitor size in the gate voltage detection circuit, and then adjusts the pulse width of the turn-on pulse signal V3 to compensate for the impact of device aging and improve the accuracy of junction temperature monitoring; The filter capacitor adjustment is dynamically adjusted by the controller to correct the pulse width of the turn-on pulse signal V3 in real time, ensuring that the junction temperature monitoring is not affected by the aging of the package and the aging of the device, thereby improving the stability and accuracy of the monitoring system.

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