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

Abstract

The application belongs to the technical field of power electronic device state monitoring, and discloses a SiC MOSFET junction temperature online monitoring circuit and method based on a turn-on delay integrator, which comprises a gate voltage detection circuit, a power source voltage detection circuit, a comparator circuit, a flip-flop circuit, an isolation circuit and a high-precision integration holding circuit; the gate voltage detection circuit measures the scaled SiC MOSFET device gate voltage and transmits the voltage to the comparator circuit; the power source voltage detection circuit measures the scaled SiC MOSFET device power source voltage V L in real time, filters the power source voltage and inversely amplifies the voltage by an inverting amplifier, and transmits the voltage to the comparator circuit; the comparator circuit compares the gate voltage and the power source voltage with the reference voltage V ref1 and the reference voltage V ref2 of the comparator, respectively, and outputs two pulse comparison signals V1 and V2, respectively, and then transmits the two pulse comparison output signals to the flip-flop circuit. The application can measure the highest junction temperature of the chip when multiple SiC MOFET chips are connected in parallel, and is more conducive to online evaluation of the state of power electronic equipment and devices.

Description

Technical Field

[0001] This invention belongs to, but is not limited to, the field of power electronic device condition monitoring technology, and particularly relates to a SiC MOSFET junction temperature online monitoring circuit and method based on a turn-on delay integrator. Background Technology

[0002] Compared to Si IGBTs, silicon carbide-metal-oxide-semiconductor field-effect transistors (SiC MOSFETs) offer lower on-resistance, higher switching speed, higher breakdown electric field, and higher high-temperature resistance, providing significant advantages in improving the performance of power electronic converters. The reliable operation of power electronic converters is directly determined by the power devices. Due to the different coefficients of thermal expansion of materials in the power semiconductor module, temperature changes cause mechanical stress. Repeated thermal cycling can eventually lead to problems such as cracks in the chip solder joints and bond wire detachment, jeopardizing the normal operation of power electronic equipment and SiC MOSFETs. SiC MOSFETs have a small chip area, high current density, and poor heat dissipation, making them more prone to problems such as excessively high junction temperatures and large temperature fluctuations during actual operation. Statistics show that over 50% of equipment and device failures are caused by junction temperature overheating and fluctuations. Therefore, online measurement or estimation of the SiC MOSFET chip junction temperature is crucial for predicting the remaining lifespan of equipment and devices.

[0003] Current technologies primarily utilize thermistor parameters of SiC MOSFETs to measure or estimate chip junction temperature online. Common thermistor parameters include the on-state voltage drop, threshold voltage, turn-on delay, and turn-off delay of SiC MOSFETs. On-state voltage drop-based online junction temperature monitoring methods are relatively mature in Si IGBTs, and therefore, on-state voltage drop is often used for online junction temperature monitoring of SiC MOSFETs. However, this method still has significant limitations when applied to SiC MOSFETs. First, the manufacturing process of SiC MOSFETs is still immature, and device aging is quite pronounced, causing drift in on-resistance and affecting the measurement of on-state voltage drop. On-state voltage drop measurement is also affected by changes in actual operating conditions. When the load current is small, its measurement accuracy is extremely low or even unusable for estimating chip junction temperature. Furthermore, since actual operation requires multiple chips to be connected in parallel and packaged into power semiconductor modules to increase power, the junction temperature calculated using on-state voltage drop measurement lacks a clear physical meaning; that is, it cannot be determined whether the obtained junction temperature is the average junction temperature of multiple chips, or the highest or lowest junction temperature. In addition, packaging aging, such as chip solder joint cracks and bond wire detachment, can also affect the measurement of on-state voltage drop, making it difficult to distinguish between the effects of device aging and packaging aging in actual measurements. Although junction temperature monitoring methods based on threshold voltage, turn-on delay, and turn-off delay are not affected by packaging aging, the high switching speed of SiC MOSFETs makes it difficult for existing technologies to accurately measure these parameters. Even if accurate measurement is possible, the low degree of change of these parameters with junction temperature means that the junction temperature measurement accuracy cannot meet the requirements.

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

[0005] To address the problems existing in the prior art, this invention provides a SiC MOSFET junction temperature online monitoring circuit and method based on a turn-on delay integrator, in order to solve the problems of low measurement accuracy, easy influence of load size changes and package aging in the existing junction temperature online monitoring technology.

[0006] The present invention is implemented as follows: an online monitoring circuit for SiC MOSFET junction temperature based on a turn-on 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 integration and hold circuit;

[0007] The gate voltage detection circuit measures the scaled gate voltage V of the SiC MOSFET device in real time using voltage follower 1. gsThe gate voltage is filtered and then 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 voltage follower 2. L The power source voltage is filtered and inversely amplified by an inverting amplifier before being transmitted to the 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 The comparison is performed, and two pulse comparison signals V1 and V2 are output respectively. These two pulse comparison output signals are then transmitted to the trigger circuit. Upon receiving the pulse comparison output signals, the trigger circuit generates a turn-on pulse signal V3, which is related to the turn-on delay of the SiC MOSFET. The width of the turn-on pulse signal V3 is T. on,dyn This width can be adjusted by adjusting the size of the filter capacitor in the gate voltage detection circuit; the isolation circuit is responsible for receiving the pulse signal from the trigger circuit and transmitting the turn-on pulse signal to the high-precision integration and holding circuit.

[0008] Furthermore, the high-precision integration and hold circuit consists of resistors R1 and R2, capacitor C1, diode D1, and switching transistor S1, and is responsible for integrating pulses with a width of T. on,dyn The turn-on pulse signal V3 is integrated over time to convert the turn-on pulse signal V3 into an integrated voltage signal V4. The junction temperature of the SiC MOSFET can be measured online by measuring this integrated voltage signal V4.

[0009] Furthermore, the reference voltage V of the comparator 1 ref1 The reference voltage V of comparator 2 is typically taken in the range of negative several hundred mV to 0V. ref2 Typically, the value ranges from 0V to several hundred mV, and the pulse width T of the turn-on pulse signal is... on,dyn Typically, the range is from a few nanoseconds to tens of nanoseconds.

[0010] Furthermore, the design of the high-precision integration and hold circuit requires the selection of diode D1 and switching transistor S1 with low leakage current; otherwise, the measurement accuracy of the SiC MOSFET junction temperature online monitoring circuit will be affected.

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

[0012] 1) First step: Place the SiC MOSFET on the heating stage and heat the SiC MOSFET to the specified junction temperature;

[0013] 2) Second step: Perform a double-pulse test on the SiC MOSFET at a given bus voltage to obtain the integrated voltage signal V4 at the chip temperature. Since the magnitude of the integrated voltage signal is independent of the operating conditions, it is not necessary to calibrate the integrated voltage signal V4 under different load currents;

[0014] 3) Third step: Change the temperature of the heating stage and repeat the second step to obtain the integral voltage signal V4 at different chip temperatures. The curve of the integral voltage signal V4 as a function of the SiC MOSFET chip temperature can be obtained by linear regression using the least squares method.

[0015] 4) Fourth step: Repeat steps one through three, changing the bus voltage to obtain the curve of the integral voltage signal V4 versus the SiC MOSFET chip temperature under different bus voltages. When the system bus voltage fluctuation range is small, the influence of the bus voltage magnitude on the measurement accuracy of the junction temperature online monitoring circuit can be ignored, thus step four can be omitted. After obtaining the integral voltage signal V4 and the SiC MOSFET chip temperature calibration curve, the junction temperature of the SiC MOSFET can be monitored online based on the calibration curve and the integral voltage signal V4 after each turn-on of the SiC MOSFET.

[0016] Another object of the present invention is to provide a computer device, the computer device including a memory and a processor, the memory storing a computer program, the computer program being executed by the processor causing the processor to perform the steps of the SiC MOSFET junction temperature online monitoring method based on a turn-on delay integrator.

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

[0018] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this invention are as follows:

[0019] First, the circuit provided by this invention is low-cost, simple in structure, and fast in response, making it easy to integrate into SiC MOSFET drive circuits. The proposed online junction temperature monitoring method is unaffected by load size and package aging, enhancing the applicability of this invention for online junction temperature monitoring of SiC MOSFETs. A method that can significantly improve the accuracy of junction temperature measurement is proposed. The proposed method does not require reducing the switching speed of the SiC MOSFET to achieve accurate measurement of thermistor parameters and will not interfere with the normal operation of the device. The proposed online junction temperature monitoring method has a clearer physical meaning in multi-chip parallel structures. The proposed method can measure the highest junction temperature of multiple SiC MOSFET chips 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 independent of the magnitude of the load current, chip solder joint cracks and bonding wire detachment, etc., which are affected by package aging. Therefore, the SiC MOSFET junction temperature online monitoring circuit and method based on the turn-on delay integrator proposed in this invention is not affected by load changes and package aging.

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

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

[0023] Second, the technical solution of this invention solves a technical problem that people have long desired to solve but have never been able to achieve:

[0024] Traditional methods assume that SiC MOSFETs have a fast turn-on speed and that the turn-on delay does not significantly change with the chip junction temperature. Only by drastically reducing the turn-on speed of the SiC MOSFET can its turn-on delay be accurately measured, and then the chip junction temperature of the SiC MOSFET can be estimated based on the measured turn-on delay. The method proposed in this invention solves this problem. Without reducing the turn-on speed of the SiC MOSFET, it proposes an online monitoring method for the SiC MOSFET junction temperature based on a turn-on delay integrator. This method estimates the chip junction temperature of the SiC MOSFET by measuring the integrated voltage signal V4, achieving high-precision online monitoring of the SiC MOSFET chip junction temperature. Furthermore, the proposed method is unaffected by the load current, making it suitable for industrial applications.

[0025] Third, in existing SiC MOSFET power device applications, junction temperature monitoring has always been a critical issue affecting system reliability and safety. Traditional temperature monitoring methods typically rely on external sensors, which cannot accurately reflect changes in the internal junction temperature of the SiC MOSFET in real time. This leads to overheating, performance degradation, and even failure of the device when operating at high power. Furthermore, existing technologies suffer from slow response speed, insufficient measurement accuracy, and the inability to reflect dynamic characteristics such as turn-on delay in real time when detecting junction temperature, limiting their application in high-power scenarios.

[0026] This invention addresses the shortcomings of traditional junction temperature monitoring methods by employing an online junction temperature monitoring circuit based on a SiC MOSFET turn-on delay integrator. By measuring the dynamic changes in gate and source voltages during MOSFET turn-on, a pulse signal related to the turn-on delay is generated. A high-precision integration and hold circuit converts this pulse signal into a voltage signal, thereby achieving accurate junction temperature monitoring. This method eliminates reliance on external sensors, directly deriving the junction temperature by monitoring the switching delay through the circuit, significantly improving the accuracy and response speed of temperature detection.

[0027] Compared with existing technologies, this invention represents a significant technological advancement. First, by utilizing circuit-level gate and source voltage signal monitoring, real-time and high-precision junction temperature monitoring is ensured. Second, employing a turn-on delay pulse signal as the basis for junction temperature monitoring greatly enhances the system's response to dynamic temperature changes, solving the problem of slow response in traditional methods. Furthermore, the circuit design effectively reduces external interference through filtering and integration-hold techniques, guaranteeing the reliability and accuracy of the monitoring results.

[0028] In power electronics applications, the junction temperature online monitoring circuit of this invention can significantly improve the safety and lifespan of SiC MOSFET devices. By monitoring the junction temperature in real time, the system can adjust its operating status promptly, avoiding device damage caused by overheating, making it particularly suitable for high-power applications such as electric vehicles and photovoltaic inverters. This circuit not only improves equipment operating efficiency but also reduces maintenance costs and downtime, providing greater safety and economic benefits for industrial production. Attached Figure Description

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

[0030] Figure 2 This is a waveform illustrating the circuit operation principle provided in the embodiments of the present invention;

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

[0032] Figure 4 These are the waveforms of the turn-on pulse signal V3 and the integral voltage signal V4 at different junction temperatures provided in the embodiments of the present invention;

[0033] Figure 5 This is the fitting curve between the junction temperature and the integral voltage signal V4 of the SiC MOSFET chip obtained by least squares linear regression according to the embodiments of the present invention;

[0034] Figure 6 These are thermal imager images provided in embodiments of the present invention;

[0035] Figure 7 These are the integrated voltage signal V4 and the junction temperature of the SiC MOSFET chip measured according to the embodiments of the present invention;

[0036] Figure 8 This is the Buck circuit continuous experimental platform provided in the embodiments of the present invention;

[0037] Figure 9 These are thermal imager images under steady-state conditions provided in embodiments of the present invention;

[0038] Figure 10 These are the measured integrated voltage signal V4 and the junction temperature of the SiC MOSFET chip provided in this embodiment of the invention.

[0039] Figure 11 This is a graph showing the experimental junction temperature measurement error provided in an embodiment of the present invention.

[0040] Figure 12This is an aging compensation measure for SiC MOSFET devices provided in the embodiments of the present invention; Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0042] like Figure 1 As shown, this embodiment of the invention provides an online monitoring circuit for SiC MOSFET junction temperature based on a turn-on delay integrator. The circuit includes: a gate voltage detection circuit, a power source voltage detection circuit, a comparator circuit, a trigger circuit, an isolation circuit, and a high-precision integration and hold circuit.

[0043] The gate voltage detection circuit measures the scaled gate voltage V of the SiC MOSFET device in real time using voltage follower 1. gs The gate voltage is filtered and then 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 voltage follower 2. L The power source voltage is filtered and inversely amplified by an inverting amplifier before being transmitted to the 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 The comparison is performed, and two pulse comparison signals V1 and V2 are output respectively. These two pulse comparison output signals are then transmitted to the trigger circuit. Upon receiving the pulse comparison output signals, the trigger circuit generates a turn-on pulse signal V3, which is related to the turn-on delay of the SiC MOSFET. The width of the turn-on pulse signal V3 is T. on,dyn This width can be adjusted by adjusting the size of the filter capacitor in the gate voltage detection circuit; the isolation circuit is responsible for receiving the pulse signal from the trigger circuit and transmitting the turn-on pulse signal to the high-precision integration and holding circuit.

[0044] The high-precision integration and hold circuit consists of resistors R1 and R2, capacitor C1, diode D1, and switching transistor S1, and is responsible for integrating and holding pulses with a width of T. on,dyn The turn-on pulse signal V3 is integrated over time to convert the turn-on pulse signal V3 into an integrated voltage signal V4. The junction temperature of the SiC MOSFET can be measured online by measuring this integrated voltage signal V4.

[0045] The reference voltage V of comparator 1 ref1 The reference voltage V of comparator 2 is typically taken in the range of negative several hundred mV to 0V.ref2 Typically, the value ranges from 0V to several hundred mV, and the pulse width T of the turn-on pulse signal is... on,dyn Typically, the range is from a few nanoseconds to tens of nanoseconds.

[0046] The design of the high-precision integration and hold circuit requires the selection of diode D1 and switching transistor S1 with low leakage current; otherwise, the measurement accuracy of the SiC MOSFET junction temperature online monitoring circuit will be affected.

[0047] The waveform of the circuit's operation principle is as follows: Figure 2 As shown, in this case, the reference voltage V of comparator 1 is... ref1 The value is 0V, and the reference voltage V of comparator 2 is... ref2 The value is 200mV, and the pulse width T of the turn-on pulse signal is... on,dyn The range was adjusted to vary from 8.7ns to 22.4ns.

[0048] One of the key components 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 using voltage follower 1, scales and filters it, and then transmits it to the comparator circuit. The power source voltage detection circuit measures the source voltage VL in real time using voltage follower 2, filters it, and then amplifies it inversely using an inverting amplifier to ensure accurate processing of the voltage signals. After these processing steps, the two voltage signals are provided to the comparator circuit for comparison. In this way, the circuit can capture and track the dynamic operating state of the MOSFET device.

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

[0050] The turn-on pulse signal V3 generated by the trigger circuit needs to be processed by an isolation circuit. The isolation circuit ensures 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 during high-frequency signal transmission, ensuring signal integrity 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 integration and hold circuit converts the pulse signal V3 into an integrated voltage signal V4. This circuit consists of resistors R1 and R2, capacitor C1, diode D1, and switching transistor S1. Using a turn-on pulse signal with a pulse width of Ton,dyn, it generates a voltage signal V4 proportional to the SiC MOSFET junction temperature through a resistor-capacitor integration method. This signal can be directly measured and used for junction temperature monitoring. To ensure measurement accuracy, diode D1 and switching transistor S1 in the integration and hold circuit need to have low leakage current to reduce signal loss. Through this integration operation, real-time, online monitoring of the SiC MOSFET junction temperature is achieved, thereby ensuring stable operation of the device under high power conditions.

[0052] To address the impact of aging on SiC MOSFET devices, this invention also provides a thermocouple-based junction temperature monitoring and compensation calibration method, the steps of which are as follows: Figure 12 As shown in the diagram, firstly, before the device starts operating, the ambient temperature is obtained by measuring the voltage across the thermocouple on the SiC MOSFET substrate. Then, after the device starts operating, the integrated voltage signal V4 obtained during the first few turn-on cycles of the SiC MOSFET is measured. The ambient temperature information obtained through the thermocouple is compared with the SiC MOSFET junction temperature information obtained through this voltage signal V4. If the difference is significant, the pulse width of the turn-on pulse signal V3 is adjusted by adjusting the size of the filter capacitor in the gate voltage detection circuit via the controller. This compensates for the aging effects of the SiC MOSFET device, ensuring that the junction temperature monitoring circuit is completely unaffected by package aging and device aging, significantly improving the stability and accuracy of the proposed method.

[0053] This invention provides a thermocouple-based SiC MOSFET junction temperature monitoring and compensation calibration method. This method aims to solve the error problems 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 this with the MOSFET's operating state. The junction temperature is calculated by integrating the voltage signal, thereby performing compensation calibration and improving the accuracy and stability of temperature monitoring.

[0054] Before the equipment is put into operation, the voltage across the SiC MOSFET substrate is measured using thermocouples to obtain the current ambient temperature. Thermocouples can accurately sense ambient temperature through changes in voltage across their terminals. This step provides a benchmark for subsequent junction temperature monitoring, ensuring effective temperature compensation and calibration during subsequent operation.

[0055] After the device is operational, the thermocouple will continue to monitor the ambient temperature as the SiC MOSFET is repeatedly turned on. Simultaneously, during each turn-on process, the system acquires the integrated voltage signal V4 of the MOSFET by collecting signals from the gate voltage detection circuit. This integrated voltage signal directly reflects the heat accumulation of the device during turn-on and can serve as an important basis for calculating the device junction temperature.

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

[0057] Adjusting the size of the filter capacitor to correct the pulse width of the pulse signal V3 can effectively eliminate errors caused by device aging. This is because the filter capacitor directly affects the circuit's response speed, which in turn affects the MOSFET junction temperature calculation process. This real-time adjustment ensures that the junction temperature monitoring results reflect the actual temperature state.

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

[0059] like Figure 3 As shown, this embodiment of the invention provides a method for online monitoring of SiC MOSFET junction temperature based on the on-time delay integrator-based SiC MOSFET junction temperature monitoring circuit. The method specifically includes:

[0060] 1) First step: Place the SiC MOSFET on the heating stage and heat the SiC MOSFET to the specified junction temperature;

[0061] 2) Second step: Perform a double-pulse test on the SiC MOSFET at a given bus voltage to obtain the integrated voltage signal V4 at the chip temperature. Since the magnitude of the integrated voltage signal is independent of the operating conditions, it is not necessary to calibrate the integrated voltage signal V4 under different load currents;

[0062] 3) Third step: Change the temperature of the heating stage and repeat the second step to obtain the integral voltage signal V4 at different chip temperatures. The curve of the integral voltage signal V4 as a function of the SiC MOSFET chip temperature can be obtained by linear regression using the least squares method.

[0063] 4) Fourth step: Repeat steps one through three, changing the bus voltage to obtain the curve of the integral voltage signal V4 versus the SiC MOSFET chip temperature under different bus voltages. When the system bus voltage fluctuation range is small, the influence of the bus voltage magnitude on the measurement accuracy of the junction temperature online monitoring circuit can be ignored, thus step four can be omitted. After obtaining the integral voltage signal V4 and the SiC MOSFET chip temperature calibration curve, the junction temperature of the SiC MOSFET can be monitored online based on the calibration curve and the integral voltage signal V4 after each turn-on of the SiC MOSFET.

[0064] This case study calibrates the relationship between the integrated voltage signal V4 and the chip junction temperature of a single SiC MOSFET. The integrated voltage signal V4 was measured at junction temperatures of 25℃, 50℃, 75℃, 100℃, 125℃, and 150℃. The waveforms of the turn-on pulse signal V3 and the integrated voltage signal V4 at different junction temperatures are shown below. Figure 4 As shown, as the junction temperature of the SiC MOSFET chip rises from 25°C to 150°C, the pulse width T of the turn-on pulse signal V3... on,dyn The pulse width T decreases from 22.4 ns to 8.7 ns, a range of 13.7 ns, with a temperature sensitivity of approximately 0.11 ns / ℃. If the system clock of the counter and controller is used to measure the pulse width T... on,dyn The junction temperature of a SiC MOSFET chip varies, and the controller's clock frequency typically ranges from 50MHz to 1GHz. The highest accuracy of this junction temperature measurement is approximately 10℃, making precise measurement difficult. As the SiC MOSFET chip junction temperature rises from 25℃ to 150℃, the integrated voltage signal V4 decreases from 2.456V to 1.072V, a variation of 1.384V. Its temperature sensitivity is approximately 11mV / ℃. If an analog-to-digital converter (ADC) chip is used to measure the change in the integrated voltage signal V4, the sampling accuracy of the ADC chip can typically reach 1mV, with a maximum junction temperature measurement accuracy of approximately 0.1℃. Based on the above analysis, the online junction temperature monitoring method for SiC MOSFETs proposed in this invention can significantly improve the accuracy of junction temperature measurement. The fitting curve between the SiC MOSFET chip junction temperature and the integrated voltage signal V4 obtained through least squares linear regression is shown below. Figure 5 As shown.

[0065] To measure the error of the proposed online monitoring method for SiC MOSFET junction temperature, based on Figure 5 The obtained fitting curves were subjected to double-pulse testing and continuous testing experiments to verify the junction temperature measurement accuracy of the proposed method.

[0066] 1) Double-pulse test experiment verification: By changing the temperature of the heating stage, the chip junction temperature was controlled at 114.2℃, and the thermal imager image is as follows. Figure 6 As shown. The integrated voltage signal V4 and the junction temperature of the SiC MOSFET chip measured by the proposed method are as follows. Figure 7 As shown, the measured integral voltage is 1.369V, the junction temperature of the SiC MOSFET chip is approximately 113.6℃, ​​and the junction temperature measurement error is less than 1℃.

[0067] 2) Continuous testing and experimental verification: such as Figure 8 The image shown is of the Buck circuit continuous experimental platform built in this case study. The thermal imager image under steady-state conditions is as follows. Figure 9 As shown, the junction temperature of the SiC MOSFET chip measured by the thermal imager is 98.6℃. The integrated voltage signal V4 and the junction temperature of the SiC MOSFET chip measured by the proposed method are as follows: Figure 10 As shown, the measured integral voltage is 1.648V, the junction temperature of the SiCMOSFET chip is approximately 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 turn-on time integrator proposed in this invention have been verified. The proposed method can achieve high-precision online monitoring of the SiC MOSFET chip junction temperature.

[0069] This invention provides a computer device, which includes a memory and a processor. The memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the SiC MOSFET junction temperature online monitoring method based on a turn-on delay integrator.

[0070] This invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the SiC MOSFET junction temperature online monitoring method based on a turn-on delay integrator.

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

[0072] In electric vehicle inverters, SiC MOSFETs are widely used for power conversion due to their high switching efficiency. However, under high-frequency switching and high-current conditions, the junction temperature of SiC MOSFETs rises rapidly, affecting their reliability and lifespan. Therefore, real-time monitoring of the SiC MOSFET junction temperature is necessary to ensure 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 inverter's power module. Through this system, the gate voltage detection circuit and the power source voltage detection circuit acquire the gate voltage Vgs and source voltage VL of the SiC MOSFET in real time, and compare them with reference voltages Vref1 and Vref2 respectively, generating pulse signals V1 and V2. The trigger circuit generates a turn-on pulse signal V3 based on these two pulse signals, representing 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 hold circuit, and the integral voltage signal V4 is obtained through a measuring device. This signal directly reflects the junction temperature change of the SiC MOSFET. By integrating this monitoring circuit into the inverter's control system, online monitoring of the SiC MOSFET junction temperature can be achieved. When the junction temperature exceeds the safety threshold, the inverter control system can promptly perform power limiting or shutdown protection to prevent the SiC MOSFET from being damaged due to overheating.

[0075] Example 2: SiC MOSFET Junction Temperature Monitoring in Photovoltaic Inverters

[0076] Photovoltaic inverters are key devices for converting direct current (DC) to alternating current (AC). With the application of SiC MOSFET technology, the conversion efficiency of photovoltaic inverters has been significantly improved. However, in high-temperature and high-power operating environments, monitoring the junction temperature of SiC MOSFETs is crucial to ensure their reliability and long-term stable operation.

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

[0078] The comparator circuit compares Vgs with Vref1 and VL with Vref2 respectively, generating 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. This pulse signal has a width of Ton,dyn and is transmitted to a high-precision integration and hold circuit. The integration and hold circuit integrates the turn-on pulse signal V3 to obtain the integrated voltage signal V4, which reflects the junction temperature of the SiC MOSFET in real time.

[0079] During the operation of a photovoltaic inverter, when the junction temperature of the SiC MOSFET reaches a critical value, the inverter's control system can automatically adjust its operating state based on the junction temperature signal, thereby preventing the SiC MOSFET from overheating and failing, and improving the safety and operating efficiency of the photovoltaic system.

[0080] Example 1: Online Junction Temperature Monitoring of High-Power SiC MOSFETs in Electric Vehicle Inverters

[0081] In the electric drive system of electric vehicles, SiC MOSFETs serve as core power switching devices, operating in high-power and high-temperature environments. Real-time monitoring of the junction temperature of the SiC MOSFETs in the inverter module is crucial for the reliable operation of the system. The junction temperature monitoring circuit based on a turn-on delay integrator provided in this invention is applied to this scenario, and its specific operation is as follows:

[0082] 1. Gate and Source Voltage Detection: The gate voltage detection circuit and the power source voltage detection circuit monitor the gate and source voltages of the MOSFET in real time and transmit them to the comparator circuit. After being processed by a filter and amplifier, the voltage signals accurately reflect the operating state of the SiC MOSFET.

[0083] 2. Pulse signal generation and control: The comparator circuit compares the voltage signal with the reference voltage and generates pulse signals V1 and V2. The trigger circuit generates a turn-on pulse signal V3 based on the pulse signals. Its pulse width Ton,dyn is adjusted by the change of the gate voltage to accurately reflect the turn-on 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 magnitude of V4, the junction temperature of the SiC MOSFET can be directly derived. The electric vehicle control system uses this circuit to monitor the junction temperature of the SiC MOSFET in the inverter in real time, preventing device overheating and ensuring system stability.

[0085] Results: In practical applications, real-time monitoring of the junction temperature of SiC MOSFETs has successfully prevented overheating of devices under high power conditions, extended the service life of inverters, and improved the reliability of electric vehicle power systems.

[0086] Example 2: SiC MOSFET Junction Temperature Monitoring in Photovoltaic Inverters

[0087] In photovoltaic power generation systems, inverters typically operate at high power for extended periods. As core switching devices, the junction temperature monitoring of SiC MOSFETs is crucial for system operation. The junction temperature monitoring circuit provided in this invention is applied to photovoltaic inverters, and its 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 monitor the gate voltage Vgs and source voltage VL of the SiC MOSFET in the photovoltaic inverter in real time, respectively. The voltage signals are transmitted to the comparator circuit, generating pulse signals V1 and V2. 2. Turn-on delay pulse signal: After comparing Vgs and VL with the reference voltage Vref, the comparator circuit generates a pulse signal V3 related to the turn-on delay. The pulse signal width Ton,dyn is precisely controlled by adjusting the size of the filter capacitor, ensuring real-time measurement of the turn-on delay.

[0088] 3. Junction Temperature Conversion in Integral-Hold Circuit: The high-precision integral-hold circuit converts the turn-on pulse signal into a voltage signal V4. This voltage value allows for real-time calculation of the SiC MOSFET's junction temperature. The photovoltaic inverter's control system utilizes this monitoring result to adjust system operating parameters in real time, preventing overheating or malfunction of the SiC MOSFET. Effect: In photovoltaic inverter applications, real-time online monitoring of the SiC MOSFET's junction temperature prevents device failure caused by prolonged high-power operation, improves the photovoltaic system's operating efficiency and stability, and reduces equipment maintenance and replacement costs.

[0089] It should be noted that embodiments of the present invention can be implemented in hardware, software, or a combination of both. The hardware portion can be implemented using dedicated logic; the software portion can be stored in memory and executed by a suitable instruction execution system, such as a microprocessor or dedicated-design hardware. Those skilled in the art will understand that the above-described devices and methods can be implemented using computer-executable instructions and / or included in processor control code, for example, such code provided on a carrier medium such as a disk, CD, or DVD-ROM, a programmable memory such as read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The devices and modules of the present invention can be implemented by hardware circuitry such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, or programmable hardware devices such as field-programmable gate arrays, programmable logic devices, etc., or by software executed by various types of processors, or by a combination of the above-described hardware circuitry and software, such as firmware.

[0090] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A SiC MOSFET junction temperature on-line monitoring circuit based on an open-loop delay integrator, characterized by, The circuit comprises a gate voltage detection circuit, a power source electrode voltage detection circuit, a comparator circuit, a flip-flop circuit, an isolation circuit and a high-precision integral holding circuit; The gate voltage detection circuit measures the scaled SiC MOSFET device gate voltage Vgs in real time through a voltage follower 1 and transmits the filtered 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 through a voltage follower 2, filters and inversely amplifies the power source electrode voltage by an inverting amplifier, and then transmits the filtered and inversely amplified power source electrode voltage to the comparator circuit; The comparator circuit compares the gate voltage and the power source electrode 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 flip-flop circuit; The flip-flop circuit receives the pulse comparison output signals and generates an opening pulse signal V3 related to the opening delay size of the SiC MOSFET, wherein the width of the opening pulse signal V3 is Ton,dyn, and the pulse width is adjusted by adjusting the size of the filter capacitor in the gate voltage detection circuit; The isolation circuit receives the pulse signal generated by the flip-flop circuit and transmits the signal to the high-precision integral holding circuit; A compensation calibration circuit for SiC MOSFET junction temperature monitoring is also provided, which comprises: A thermocouple is installed 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 is used to generate an integral voltage signal V4 during multiple opening processes of the SiC MOSFET; A comparison module is used to compare the ambient temperature information measured by the thermocouple and the SiC MOSFET junction temperature information calculated by the integral voltage signal V4; A controller connected to the comparison module 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 opening pulse signal V3, thereby compensating for the aging effect of the SiC MOSFET device and ensuring the accuracy and stability of the junction temperature monitoring; The high-precision integral holding circuit is composed of resistors R1 and R2, a capacitor C1, a diode D1 and a switch tube S1, which is used to integrate the opening pulse signal V3 with a pulse width of Ton,dyn in the time scale, thereby converting the opening pulse signal V3 into an integral voltage signal V4, and realizing online measurement of the SiC MOSFET junction temperature by measuring the integral voltage signal V4.

2. The on-delay integrator-based SiC MOSFET junction temperature online monitoring circuit according to claim 1, characterized in that, The reference voltage Vref1 of the comparator 1 is 0 volts, the reference voltage Vref2 of the comparator 2 is 200 millivolts, and the pulse width Ton,dyn of the opening pulse signal ranges from 8.7 nanoseconds to 22.4 nanoseconds.

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

4. The on-delay integrator based SiC MOSFET junction temperature on-line monitoring circuit 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 is adjusted according to the requirement of the pulse width Ton,dyn in the actual application, so as to ensure the stability and accuracy of the turn-on pulse signal V3.

5. A SiC MOSFET junction temperature online monitoring method based on the SiC MOSFET junction temperature online monitoring circuit based on the turn-on delay integrator according to any one of claims 1-4, characterized in that, The method comprises the following steps: 1) measuring the gate voltage Vgs of the SiC MOSFET device in real time through the gate voltage detection circuit, and filtering the measured gate voltage; 2) measuring the power source voltage VL of the SiC MOSFET device in real time through the power source voltage detection circuit, and filtering and inversely proportional amplifying the measured power source voltage; 3) comparing the filtered gate voltage with a reference voltage Vref1, and outputting a first pulse signal V1; comparing the filtered power source voltage with a reference voltage Vref2, and outputting a second pulse signal V2; 4) generating a turn-on pulse signal V3 according to the pulse signals V1 and V2, wherein the pulse width Ton,dyn of the turn-on pulse signal is related to the turn-on delay of the SiC MOSFET; 5) transmitting the turn-on pulse signal V3 to a high-precision integration holding circuit, converting the pulse signal V3 into an integral voltage signal V4 through the integration holding circuit, and monitoring the junction temperature of the SiC MOSFET online through the integral voltage signal.

6. The SiC MOSFET junction temperature on-line monitoring method based on the open-up delay integrator according to claim 5, characterized in that, The value of the reference voltage Vref1 in the step 3 is 0 volt, and the value of the reference voltage Vref2 is 200 millivolts, so as to ensure that the generated pulse signals V1 and V2 can effectively reflect the turn-on state of the SiC MOSFET; the diode and the switch tube with small drain current are used in the step 5, so as to improve the accuracy of the high-precision integration holding circuit, and thus ensure the stability and accuracy of the junction temperature measurement.

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