A SiC MOSFET junction temperature measurement method with multi-parameter aging compensation

Abstract

The application discloses a SiC MOSFET junction temperature measurement method with multi-parameter aging compensation, and establishes temperature-sensitive characteristic models of threshold voltage, turn-on delay time and on-resistance through experiments; a SiC MOSFET driving and parameter acquisition system is built; three electrical parameters are collected in different time periods, namely threshold voltage in an offline state, turn-on delay time in an on process and on-resistance in a working process after turn-on; the temperature-sensitive characteristics of on-resistance in a working process of the SiC MOSFET are compensated by using threshold voltage and turn-on delay time; and real-time junction temperature is predicted by using the temperature-sensitive electrical parameter of the on-resistance after aging compensation. The application solves the problem that the on-resistance changes due to device aging when measuring the junction temperature of the SiC MOSFET, thereby making the junction temperature measurement result seriously deviate, and effectively guarantees the healthy and safe working of the SiC MOSFET.

Description

Technical Field

[0001] This invention belongs to the field of SiC MOSFET junction temperature monitoring technology, and relates to a SiC MOSFET junction temperature measurement method with multi-parameter aging compensation. Background Technology

[0002] Compared to traditional silicon materials, silicon carbide (SiC) materials possess advantages such as a large bandgap, strong breakdown field, and high carrier mobility. These superior properties enable SiC power devices to exhibit better high-temperature, high-voltage, and high-frequency characteristics. Currently, power semiconductor devices, represented by SiC MOSFETs, have been widely used in various fields, including locomotive traction, electric vehicles, smart grids, and new energy power generation. With increasingly widespread applications, the reliability and health management of SiC MOSFETs have become key concerns. Among these, the junction temperature of SiC MOSFETs is a crucial factor in reliability, making SiC MOSFET junction temperature measurement a research hotspot. Currently, using the temperature-sensitive electrical parameter method to measure the junction temperature of SiC MOSFETs is considered the most promising approach. However, most temperature-sensitive electrical parameters change with device aging, leading to increasingly larger measurement errors and hindering the health management of SiC MOSFETs. Therefore, developing an aging-compensated SiC MOSFET junction temperature measurement method is of great significance. Summary of the Invention

[0003] The purpose of this invention is to provide a SiC MOSFET junction temperature measurement method with multi-parameter aging compensation, which solves the problem that the electrical parameters of the temperature-sensitive electrical parameter method change with the aging of SiC MOSFET during junction temperature measurement, resulting in increasingly larger measurement errors.

[0004] The technical solution adopted in this invention is a SiC MOSFET junction temperature measurement method with multi-parameter aging compensation. This method collects three electrical parameters at different time periods: threshold voltage, turn-on delay time, and on-resistance. After two stages of compensation, the compensated on-resistance is used to achieve online measurement of the SiC MOSFET junction temperature. The specific implementation steps are as follows:

[0005] Step 1: Establish temperature-sensitive characteristic curve models of threshold voltage, turn-on delay time, and on-resistance of SiC MOSFET through experiments;

[0006] Step 2: Build a SiC MOSFET driving and parameter acquisition system to drive the SiC MOSFET on and off and acquire the parameters used.

[0007] Step 3: When the SiC MOSFET is not working, the offset of the threshold voltage is calculated using the collected case temperature and threshold voltage. This offset is then added to the curve model of turn-on delay time versus junction temperature obtained in Step 1 for compensation.

[0008] Step 4: During the turn-on process of the SiC MOSFET, the system collects the turn-on delay time and calculates the real-time junction temperature of the device using the curve model of the compensated turn-on delay time versus junction temperature.

[0009] Step 5: Collect the on-resistance and calculate the junction temperature based on the on-resistance temperature-sensitive characteristic curve model obtained in Step 1. Compare the real-time junction temperature of the device in Step 4 with the junction temperature calculated in Step 5, and then calculate the change in on-resistance. Add the change in on-resistance to the on-resistance temperature-sensitive characteristic curve model obtained in Step 1 to perform aging compensation for on-resistance.

[0010] Step 6: After the compensation process is completed, the junction temperature of the SiC MOSFET is measured using the compensated on-resistance temperature-sensitive characteristic curve model during normal operation of the SiC MOSFET device.

[0011] The invention is further characterized in that,

[0012] The parameters used in step 2 are those collected at different time periods, namely the threshold voltage in the offline state, the turn-on delay time during the turn-on process, and the on-resistance during the working process after turn-on.

[0013] In step 2, the SiC MOSFET driving and parameter acquisition system includes a power supply module, an FPGA control module, a driving module, a protection module, a parameter acquisition module, a case temperature acquisition module, and a serial communication module.

[0014] Step 3 specifically involves:

[0015] When the SiC MOSFET is not operating, it does not generate heat on its own, and the junction temperature is equal to the case temperature. Therefore, the case temperature measured by the case temperature acquisition module is equal to the junction temperature. The threshold voltage value V is calculated using this junction temperature and the threshold voltage temperature-sensitive characteristic curve obtained in step 1. TH1 Then, the parameter acquisition module is used to measure the current true value of the threshold voltage V. TH2 V TH1 With V TH2 The difference ΔV TH This is the offset of the threshold voltage, and the threshold voltage does not change with the temperature sensitivity of the SiC MOSFET after aging. The relationship between the turn-on delay time and the threshold voltage is shown in equation (1).

[0016]

[0017] In equation (1), T d(on) To delay the activation time, R g C is the gate resistance. iss For the output junction capacitance, V CC With V EE These are the positive and negative driving voltages of the gate drive circuit, respectively.

[0018] As can be seen from equation (1), the change in turn-on delay time mainly depends on the change in threshold voltage. Therefore, the offset of threshold voltage is added to the temperature-sensitive characteristic curve of turn-on delay time obtained in step 1 for aging compensation.

[0019] Step 4 specifically involves the following steps: During the SiC MOSFET turn-on process, the parameter acquisition module measures the turn-on delay time. When measuring the turn-on delay time, the driver module needs to switch to a large gate resistor in the hundreds of ohms range to improve the temperature sensitivity of the turn-on delay time. The measured turn-on delay time is then used to calculate the current junction temperature based on the temperature-sensitive characteristic curve of the turn-on delay time obtained in Step 3. In the next switching cycle after the turn-on delay measurement is completed, the gate resistor is switched back to a small resistance value to reduce the switching losses during the operation of the SiC MOSFET.

[0020] Step 5 specifically involves the following steps: After the turn-on process in step 4 is completed, the parameter acquisition module measures the on-resistance and then calculates a junction temperature value T based on the on-resistance temperature-sensitive characteristic curve obtained in step 1. j0 At this point, due to the aging of the SiC MOSFET device, the temperature-sensitive characteristic of its on-resistance also changes, resulting in an increase in the junction temperature T. j0 This is not accurate; the junction temperature obtained in step 4 is denoted as T. j1 Because of T j1 To determine the junction temperature after compensation, it is assumed that T j1 To determine the true junction temperature, T j1 With T j0 The difference ΔT j Add the on-resistance temperature-sensitive characteristic curve obtained in step 1 to perform aging compensation of the on-resistance.

[0021] The beneficial effects of this invention are:

[0022] This invention presents a multi-parameter aging compensation method for measuring SiC MOSFET junction temperature. It collects three electrical parameters at different time periods: the threshold voltage in offline mode, the turn-on delay time during turn-on, and the on-resistance during operation after turn-on. After two stages of compensation, the compensated on-resistance is used to achieve online measurement of the SiC MOSFET junction temperature. This method can be implemented on SiC MOSFET smart drivers, solving the problem that the measurement error increases due to the changing electrical parameters as the SiC MOSFET ages, as with the temperature-sensitive electrical parameter method. This improves the accuracy of SiC MOSFET junction temperature measurement and provides a basis for the health management of SiC MOSFETs. Attached Figure Description

[0023] Figure 1 This is a flowchart of the compensation process in the SiC MOSFET junction temperature measurement method with multi-parameter aging compensation of the present invention;

[0024] Figure 2 This is a block diagram of the SiC MOSFET driving and parameter acquisition system in step 2 of the SiC MOSFET junction temperature measurement method with multi-parameter aging compensation of the present invention. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0026] This invention presents a multi-parameter aging compensation method for measuring the junction temperature of SiC MOSFETs. It utilizes three electrical parameters acquired at different time intervals: threshold voltage, turn-on delay time, and on-resistance. After two stages of compensation, the compensated on-resistance is used to achieve online measurement of the SiC MOSFET junction temperature. Figure 1 As shown, please follow these steps:

[0027] Step 1: Establish temperature-sensitive characteristic curve models of threshold voltage, turn-on delay time and on-resistance of SiC MOSFET through experiments.

[0028] Step 2: Build a SiC MOSFET driving and parameter acquisition system to drive the SiC MOSFET on and off and acquire the parameters used.

[0029] like Figure 2 As shown, the SiC MOSFET driving and parameter acquisition system includes a power supply module, an FPGA control module, a driving module, a protection module, a parameter acquisition module, a case temperature acquisition module, and a serial communication module.

[0030] The power module is used to power the entire system and has functions such as high voltage isolation and undervoltage protection;

[0031] The FPGA control module is used to drive and protect the SiC MOSFET, process the collected SiC MOSFET electrical parameters, calculate the junction temperature, and send data to the host computer.

[0032] The driver module is used to turn SiC MOSFETs on and off;

[0033] The protection module is used to send a fault signal to the FPGA control module when a SiC MOSFET fails.

[0034] The parameter acquisition module is used to acquire the threshold voltage, turn-on delay time, and on-resistance of the SiC MOSFET and send them to the FPGA control module for processing.

[0035] The shell temperature acquisition module uses a temperature sensor to collect the shell temperature and sends it to the FPGA control module for processing.

[0036] The serial communication module is used for communication between the FPGA control module and the host computer to send SiC MOSFET junction temperature information;

[0037] The parameters used are those collected at different time periods, namely the threshold voltage in offline state, the turn-on delay time during the turn-on process, and the on-resistance during the working process after turn-on.

[0038] Step 3: When the SiC MOSFET is not working, the offset of the threshold voltage is calculated using the collected case temperature and threshold voltage. This offset is then added to the curve model of turn-on delay time versus junction temperature obtained in Step 1 for compensation.

[0039] When the SiC MOSFET is not operating, it does not generate heat on its own, and the junction temperature is equal to the case temperature. Therefore, the case temperature measured by the case temperature acquisition module is equal to the junction temperature. The threshold voltage value V is calculated using this junction temperature and the threshold voltage temperature-sensitive characteristic curve obtained in step 1. TH1 Then, the parameter acquisition module is used to measure the current true value of the threshold voltage V. TH2 V TH1 With V TH2 The difference ΔV TH This is the offset of the threshold voltage, and the threshold voltage does not change with the temperature sensitivity of the SiC MOSFET after aging. The relationship between the turn-on delay time and the threshold voltage is shown in equation (1).

[0040]

[0041] In equation (1), T d(on) To delay the activation time, R g C is the gate resistance. issFor the output junction capacitance, V CC With V EE These are the positive and negative driving voltages of the gate drive circuit, respectively.

[0042] As can be seen from equation (1), the change in turn-on delay time mainly depends on the change in threshold voltage. Therefore, the offset of threshold voltage is added to the temperature-sensitive characteristic curve of turn-on delay time obtained in step 1 for aging compensation.

[0043] Step 4: During the turn-on process of the SiC MOSFET, the system collects the turn-on delay time and calculates the real-time junction temperature of the device using the curve model of the compensated turn-on delay time versus junction temperature.

[0044] Step 4 specifically involves the following steps: During the SiC MOSFET turn-on process, the parameter acquisition module measures the turn-on delay time. When measuring the turn-on delay time, the driver module needs to switch to a large gate resistor in the hundreds of ohms range to improve the temperature sensitivity of the turn-on delay time. The measured turn-on delay time is then used to calculate the current junction temperature based on the temperature-sensitive characteristic curve of the turn-on delay time obtained in Step 3. In the next switching cycle after the turn-on delay measurement is completed, the gate resistor is switched back to a small resistance value to reduce the switching losses during the operation of the SiC MOSFET.

[0045] Step 5: After the turn-on process described in Step 4 is completed, immediately collect the on-resistance and calculate the junction temperature based on the on-resistance temperature-sensitive characteristic curve model obtained in Step 1 (this junction temperature is not accurate due to device aging). Compare the real-time junction temperature of the device in Step 4 with the junction temperature calculated in Step 5, and then calculate the change in on-resistance. Add the change in on-resistance to the on-resistance temperature-sensitive characteristic curve model obtained in Step 1 to perform aging compensation for on-resistance.

[0046] Step 5 specifically involves the following: After the turn-on process in step 4 is completed, the parameter acquisition module immediately measures the on-resistance and then calculates a junction temperature value T from the on-resistance temperature-sensitive characteristic curve obtained in step 1. j0 At this point, due to the aging of the SiC MOSFET device, the temperature-sensitive characteristic of its on-resistance also changes, resulting in an increase in the junction temperature T. j0 This is not accurate; the junction temperature obtained in step 4 is denoted as T. j1 Because of T j1 To determine the junction temperature after compensation, it is assumed that T j1 To determine the true junction temperature, T j1 With T j0 The difference ΔT j Add the on-resistance temperature-sensitive characteristic curve obtained in step 1 to perform aging compensation of the on-resistance.

[0047] Step 6: After the compensation process is completed, the junction temperature of the SiC MOSFET is measured using the compensated on-resistance temperature-sensitive characteristic curve model during normal operation of the SiC MOSFET device.

[0048] The aging compensation of the SiC MOSFET on-resistance temperature-sensitive characteristic curve is completed through steps 3, 4 and 5. Since the aging of SiC MOSFET in actual operation requires a very long time, it is only necessary to periodically use steps 3, 4 and 5 to perform aging compensation. After compensation, for a period of time, online junction temperature measurement of SiC MOSFET is only required through step 6 using the on-resistance.

[0049] As can be seen from the above, the present invention provides a SiC MOSFET junction temperature measurement method with multi-parameter aging compensation, which can be implemented on SiC MOSFET smart drivers to compensate for the impact of device aging on temperature-sensitive electrical parameters, improve the accuracy of junction temperature measurement, realize online junction temperature measurement, and provide a basis for the health management of SiC MOSFETs.

Claims

1. A method for measuring the junction temperature of a SiC MOSFET with multi-parameter aging compensation, characterized in that, Three electrical parameters—threshold voltage, turn-on delay time, and on-resistance—are collected at different time intervals. After two stages of compensation, the compensated on-resistance is used to achieve online measurement of the SiC MOSFET junction temperature. The specific implementation steps are as follows: Step 1: Establish temperature-sensitive characteristic curve models of threshold voltage, turn-on delay time, and on-resistance of SiC MOSFET through experiments; Step 2: Build a SiC MOSFET driving and parameter acquisition system to drive the SiC MOSFET on and off and acquire the parameters used. Step 3: When the SiC MOSFET is not working, the offset of the threshold voltage is calculated using the collected case temperature and threshold voltage. This offset is then added to the curve model of turn-on delay time versus junction temperature obtained in Step 1 for compensation. Step 4: During the turn-on process of the SiC MOSFET, the system collects the turn-on delay time and calculates the real-time junction temperature of the device using the curve model of the compensated turn-on delay time versus junction temperature. Step 5: Collect the on-resistance and calculate the junction temperature based on the on-resistance temperature-sensitive characteristic curve model obtained in Step 1. Compare the real-time junction temperature of the device in Step 4 with the junction temperature calculated in Step 5, and then calculate the change in on-resistance. Add the change in on-resistance to the on-resistance temperature-sensitive characteristic curve model obtained in Step 1 to perform aging compensation for on-resistance. Step 6: After the compensation process is completed, the junction temperature of the SiC MOSFET is measured using the compensated on-resistance temperature-sensitive characteristic curve model during normal operation of the SiC MOSFET device.

2. The SiC MOSFET junction temperature measurement method with multi-parameter aging compensation according to claim 1, characterized in that, The parameters used in step 2 are parameters collected at different time periods, namely the threshold voltage in the offline state, the activation delay time during the activation process, and the on-resistance during the working process after activation.

3. The SiC MOSFET junction temperature measurement method with multi-parameter aging compensation according to claim 1, characterized in that, The SiC MOSFET driving and parameter acquisition system in step 2 includes a power supply module, an FPGA control module, a driving module, a protection module, a parameter acquisition module, a case temperature acquisition module, and a serial communication module.

4. The SiC MOSFET junction temperature measurement method with multi-parameter aging compensation according to claim 2, characterized in that, Step 3 specifically involves: When the SiC MOSFET is not operating, it does not generate heat on its own, and the junction temperature is equal to the case temperature. Therefore, the case temperature measured by the case temperature acquisition module is equal to the junction temperature. The threshold voltage value is then calculated using this junction temperature and the threshold voltage temperature-sensitive characteristic curve obtained in step 1. ; Then, the parameter acquisition module is used to measure the actual value of the current threshold voltage. ; and The difference This is the offset of the threshold voltage, and the threshold voltage does not change with the temperature sensitivity of the SiC MOSFET after aging. The relationship between the turn-on delay time and the threshold voltage is shown in equation (1). (1) In equation (1), Due to the delay in opening time, Gate resistor, For output junction capacitance, and These are the positive and negative drive voltages of the gate drive circuit, respectively. This is the threshold voltage of the SiC MOSFET; As can be seen from equation (1), the change in turn-on delay time mainly depends on the change in threshold voltage. Therefore, the offset of threshold voltage is added to the temperature-sensitive characteristic curve of turn-on delay time obtained in step 1 for aging compensation.

5. The SiC MOSFET junction temperature measurement method with multi-parameter aging compensation according to claim 1, characterized in that, Step 4 specifically involves the following steps: During the SiC MOSFET turn-on process, the parameter acquisition module measures the turn-on delay time. When measuring the turn-on delay time, the driver module needs to switch to a large gate resistor in the hundreds of ohms range to improve the temperature sensitivity of the turn-on delay time. The measured turn-on delay time is then used to calculate the current junction temperature based on the temperature-sensitive characteristic curve of the turn-on delay time obtained in step 3. In the next switching cycle after the turn-on delay measurement is completed, the gate resistor is switched back to a small resistance value to reduce the switching losses during the operation of the SiC MOSFET.

6. The SiC MOSFET junction temperature measurement method with multi-parameter aging compensation according to claim 1, characterized in that, Step 5 specifically involves: after the turn-on process described in step 4 is completed, the parameter acquisition module measures the on-resistance, and then calculates a junction temperature value from the on-resistance temperature-sensitive characteristic curve obtained in step 1. At this point, due to the aging of the SiC MOSFET device, the temperature-sensitive characteristics of its on-resistance also change, resulting in a change in the junction temperature value. This is not accurate; the temperature obtained in step 4 is recorded as... ,because To calculate the junction temperature after compensation, it is assumed that... To achieve the true junction temperature, and The difference Add the on-resistance temperature-sensitive characteristic curve obtained in step 1 to perform aging compensation of the on-resistance.

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