Online monitoring method and system for junction temperature of silicon carbide MOSFET device

Abstract

The invention belongs to the field of power device state detection, and relates to a silicon carbide MOSFET device junction temperature on-line monitoring method and system, and the method comprises the steps: converting dynamic current information into an induction voltage signal Vsense; the induced voltage signal Vsense is converted into voltage pulse signals VCP1, VCP2, VCP3 and VCP4, wherein the voltage pulse signals VCP1, VCP2, VCP3 and VCP4 comprise turn-on / turn-off delay time and turn-on / turn-off current slope information; extracting rough time Tcoarse between the rising edge / falling edge of the PWM signal and the rising edges of the voltage pulse signals VCP1, VCP2, VCP3 and VCP4; the rising edge / falling edge of the PWM signal and the rising edges of the voltage pulse signals VCP1, VCP2, VCP3 and VCP4 are positioned, and the fine time Tfine between the edges and the rising edges of the adjacent clock signals is calculated; and superposing the rough time Tcoarse and the fine time Tfine to obtain accurate turn-on / turn-off delay time and turn-on / turn-off current slope information of the device, and obtaining the junction temperature of the device by comparing the turn-on / turn-off delay time and the relationship between the turn-on / turn-off current slope information and the junction temperature of the device, thereby facilitating online extraction of the junction temperature.

Description

Technical Field

[0001] The present invention belongs to the field of power device state detection, and in particular relates to an online monitoring method and system for junction temperature of a silicon carbide MOSFET device. Background Art

[0002] The widespread application of silicon carbide devices with high temperature resistance, high voltage resistance and low loss characteristics has brought new development opportunities to the power electronics industry. However, compared with silicon-based devices, fast-opening silicon carbide devices are more susceptible to potential negative factors such as crosstalk. Therefore, how to ensure their safe and reliable operation has become a key research direction of power electronics at this stage. The junction temperature of the device is a key parameter that can reflect the operating status of the device. How to achieve its online monitoring is one of the foundations of silicon carbide device protection and health detection.

[0003] Device junction temperature monitoring based on thermistor electrical parameters has attracted widespread attention due to its non-invasive and online features. However, with the popularization of wide bandgap materials such as silicon carbide and gallium nitride in semiconductor devices, the sensitivity of device electrical parameters to junction temperature has also decreased, making it more difficult to implement device junction temperature monitoring based on thermistor electrical parameters.

[0004] Therefore, it is urgent to propose an online monitoring solution for the junction temperature of silicon carbide MOSFET devices to solve the above problems. Summary of the invention

[0005] The invention discloses a method and system for online monitoring junction temperature of a silicon carbide MOSFET device, which mainly solves the problem of difficulty in monitoring junction temperature of devices based on thermal-sensitive electrical parameters.

[0006] To achieve the above object, the present invention provides a method for online monitoring of junction temperature of a silicon carbide MOSFET device, comprising the following steps: Convert dynamic current information into induced voltage signal V sense ; The induced voltage signal V sense Converted into a voltage pulse signal containing the on / off delay time and on / off current slope information V CP1 , V CP2 , V CP3 and V CP4 ; Extract PWM signal rising edge / falling edge and voltage pulse signal V CP1 , V CP2 , VCP3 and V CP4 Rough time between rising edges T coarse ; Positioning PWM signal rising edge / falling edge, voltage pulse signal V CP1 , V CP2 , V CP3 and V CP4 rising edge and calculates the fine time between the above edge and the adjacent clock signal rising edge T fine ; The rough time T coarse With fine time T fine By superimposing them, the precise turn-on / turn-off delay time and turn-on / turn-off current slope information of the device are obtained, and the device junction temperature is obtained by comparing the relationship between the turn-on / turn-off delay time and turn-on / turn-off current slope information and the device junction temperature.

[0007] Furthermore, the induced voltage signal V sense Converted into voltage pulse signal V CP1 , V CP2 , V CP3 and V CP4 The process includes the following steps: Based on the induced voltage signal V sense Get its mirror voltage V sense_n and V sense_p ; Mirror voltage V sense_n and V sense_p Perform voltage limiting to obtain a voltage signal that only retains the forward voltage V s_n and V s_p ; Will V s_n The device turn-on delay and current slope information contained in the V CP1 and V CP2 ; Vs_p The device shutdown delay information and current slope information contained in the V CP3 as well as V CP4 .

[0008] Further, rough time T coarse The extraction includes: When the input signal has a starting edge, the rising edge of the clock signal starts counting, and when the input signal has an ending edge, the counting ends and the count value is saved. N cnt , the count value N cnt With clock cycle T cycle Multiplying by , we can get the rough time between edges T coarse .

[0009] Furthermore, the rough time T coarse include: PWM signal rising edge and voltage pulse signal V CP1 The approximate time between rising edges is T coarse_01 ; Voltage pulse signal V CP1 Rising edge and voltage pulse signal V CP2 The rough time between rising edges is T coarse_12 ; PWM signal falling edge and voltage pulse signal V CP3 The approximate time between rising edges is T coarse_34 ; Voltage pulse signal V CP3 Rising edge and voltage pulse signal V CP4 The approximate time between rising edges is T coarse_45 .

[0010] Further, fine time T fine The calculation includes: Count the number of input pulse signals N cnt_fine and multiply it by T delayThe precise time between the edge to be measured and the rising edge of the clock can be obtained T fine .

[0011] Furthermore, the fine time T fine include: The fine time at the rising edge of the PWM signal is T fine_rising ; Voltage pulse signal V CP1 The fine time at the rising edge is T fine_1 ; Voltage pulse signal V CP2 The fine time at the rising edge is T fine_2 ; The fine time at the falling edge of the PWM signal is T fine_falling ; Voltage pulse signal V CP3 The fine time at the rising edge is T fine_4 ; Voltage pulse signal V CP4 The fine time at the rising edge is T fine_5 .

[0012] Furthermore, the rising edge of the PWM signal and the voltage pulse signal V CP1 Time between rising edges T t0-t1 , T t0-t1 The turn-on delay time of the corresponding device; Voltage pulse signal V CP1 Rising edge and voltage pulse signal V CP2 Time between rising edges T t1-t2 , T t1-t2 The turn-on current slope information of the corresponding device; PWM signal falling edge and voltage pulse signal V CP3 Time between rising edges T t3-t4 ; T t3-t4 The turn-off delay time of the corresponding device; Voltage pulse signalV CP3 Rising edge and voltage pulse signal V CP4 Time between rising edges T t4-t5 ; T t4-t5 The corresponding device's shutdown current slope information.

[0013] The present invention also provides a silicon carbide MOSFET device junction temperature online monitoring system, comprising a silicon carbide MOSFET device, a dynamic current information conversion unit, a pulse width counting unit, a high-precision edge positioning unit and a device junction temperature conversion unit; The dynamic current information conversion unit is electrically connected to the silicon carbide MOSFET device and is used to convert the induced voltage signal V sense Converted into a voltage pulse signal containing the on / off delay time and on / off current slope information V CP1 , V CP2 , V CP3 and V CP4 ; The pulse width counting unit and the high-precision edge positioning unit are electrically connected to the dynamic current information conversion unit. The pulse width counting unit extracts the rising edge / falling edge of the PWM signal and the voltage pulse signal. V CP1 , V CP2 , V CP3 and V CP4 Rough time between rising edges T coarse The high-precision edge positioning unit is used to locate the rising edge / falling edge of the PWM signal and the voltage pulse signal V CP1 , V CP2 , V CP3 and V CP4 rising edge and calculates the fine time between the above edge and the adjacent clock signal rising edge T fine ; The device junction temperature conversion unit is electrically connected to the dynamic current information conversion unit and the pulse width counting unit, and is used to convert the corresponding rough time obtained in the pulse width calculation unit into T coarse, and the corresponding fine time obtained in the high-precision edge positioning unit T fine By superimposing them, the precise turn-on / turn-off delay time and turn-on / turn-off current slope information of the device can be obtained.

[0014] Furthermore, it also includes a reverse follower, a forward follower and a voltage limiter electrically connected, wherein the reverse follower and the forward follower are used to obtain the induced voltage signal V sense The mirror voltage V sense_n and V sense_p , the voltage limiter is used based on the mirror voltage V sense_n and V sense_p Obtain a voltage signal that retains only the forward voltage V s_n as well as V s_p .

[0015] Furthermore, the high-precision edge positioning unit includes a delay unit, a trigger and a register, each delay unit corresponds to a trigger and a register, and the delay unit has a delay time T delay The trigger is used to latch the state of the input pulse signal at each rising edge of the external clock and save it in the corresponding register.

[0016] The technical solution provided by the present invention has at least the following technical effects: 1. The present invention utilizes the parasitic inductance of the silicon carbide MOSFET device itself L SS , and a simple comparison circuit can realize the extraction of device turn-on / off delay time, turn-on / off current slope and other electrical parameters.

[0017] 2. Some circuits in the present invention (pulse width calculation unit, high-precision edge positioning unit, device junction temperature conversion unit) can be flexibly arranged inside a programmable logic chip, have good portability, and facilitate the online extraction of junction temperature.

[0018] 3. The present invention can realize high-precision identification of pulse width (picosecond precision identification). In the process of junction temperature extraction, it is not necessary to amplify the thermal-sensitive electrical parameters of silicon carbide MOSFET devices, and it is not necessary to destroy the normal working conditions of power electronic equipment, which is conducive to improving the reliability of converter operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0020] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 This is a flow chart of a method for online monitoring junction temperature of a silicon carbide MOSFET device according to an embodiment of the present invention; Figure 2 This is a structural diagram of an online monitoring system for junction temperature of a silicon carbide MOSFET device according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a dynamic current information conversion unit according to an embodiment of the present invention; Figure 4 A waveform diagram of a dynamic current information conversion unit according to an embodiment of the present invention; Figure 5 Schematic diagram of the time composition between edges to be measured according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of a high-precision edge positioning unit according to an embodiment of the present invention; Figure 7 A silicon carbide MOSFET device driving test platform used in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the embodiments of the present invention, and should not be construed as limiting the present invention.

[0022] Embodiment 1: Figure 1 As shown, this embodiment discloses an online monitoring method for junction temperature of a silicon carbide MOSFET device, which mainly solves the problem of difficulty in monitoring junction temperature of devices based on thermal sensitive electrical parameters. It includes the following steps: S 1 :Through the source parasitic inductance of SiC MOSFET devices L SS Convert dynamic current information into induced voltage signal V sense；

[0023] S 2 :The voltage signal is converted into V sense Converted into a voltage pulse signal containing the on / off delay time and on / off current slope information V CP1 , V CP2 , V CP3 and V CP4 , and send the voltage pulse signal to the pulse width calculation unit and the high-precision edge positioning unit respectively; specifically based on the induced voltage signal V sense Get its mirror voltage V sense_n and V sense_p ; For mirror voltage V sense_n and V sense_p Perform voltage limiting to obtain a voltage signal that only retains the forward voltage V s_n and V s_p ;Will V s_n The device turn-on delay and current slope information contained in the V CP1 and V CP2 ; V s_p The device shutdown delay information and current slope information contained in the V CP3 as well as V CP4 .

[0024] S 3 : Through the pulse width calculation unit, extract the PWM signal rising edge / falling edge and voltage pulse signal V CP1 , V CP2 , V CP3 and V CP4 Rough time between rising edges T coarse Specifically, the rising edge of the clock signal starts to be counted when the input signal has a starting edge, and ends the counting when the input signal has an ending edge, and the count value is saved. Ncnt , the count value N cnt With clock cycle T cycle Multiplying by , we can get the rough time between edges T coarse ; The approximate time T coarse include: PWM signal rising edge and voltage pulse signal V CP1 The approximate time between rising edges is T coarse_01 ; Voltage pulse signal V CP1 Rising edge and voltage pulse signal V CP2 The rough time between rising edges is T coarse_12 ; PWM signal falling edge and voltage pulse signal V CP3 The approximate time between rising edges is T coarse_34 ; Voltage pulse signal V CP3 Rising edge and voltage pulse signal V CP4 The approximate time between rising edges is T coarse_45 .

[0025] S 4 :Use high-precision edge positioning unit to locate the rising / falling edge of PWM signal and voltage pulse signal V CP1 , V CP2 , V CP3 and V CP4 rising edge and calculates the fine time between the above edge and the adjacent clock signal rising edge T fine ; Specifically count the number of input pulse signals N cnt_fine and multiply it by T delay The precise time between the edge to be measured and the rising edge of the clock can be obtained T fine .

[0026] Furthermore, the fine time T fine include: The fine time at the rising edge of the PWM signal is T fine_rising ; Voltage pulse signal V CP1 The fine time at the rising edge is T fine_1 ; Voltage pulse signal V CP2 The fine time at the rising edge is T fine_2 ; The fine time at the falling edge of the PWM signal is T fine_falling ; Voltage pulse signal V CP3 The fine time at the rising edge is T fine_4 ; Voltage pulse signal V CP4 The fine time at the rising edge is T fine_5 .

[0027] S 5 :The device junction temperature conversion unit converts the corresponding rough time obtained in the pulse width calculation unit T coarse , and the corresponding fine time obtained in the high-precision edge positioning unit T fine By adding them together, we can get the accurate turn-on / turn-off delay time and turn-on / turn-off current slope information of the device. Finally, by comparing the relationship between the above parameters and the device junction temperature, we can get the device junction temperature.

[0028] PWM signal rising edge and voltage pulse signal V CP1 Time between rising edges T t0-t1 , T t0-t1 The turn-on delay time of the corresponding device; Voltage pulse signal V CP1 Rising edge and voltage pulse signal V CP2 Time between rising edges T t1-t2 , T t1-t2 The turn-on current slope information of the corresponding device; PWM signal falling edge and voltage pulse signal V CP3 Time between rising edges T t3-t4 ; T t3-t4 The turn-off delay time of the corresponding device; Voltage pulse signal V CP3 Rising edge and voltage pulse signal V CP4 Time between rising edges T t4-t5 ; T t4-t5 The turn-off current slope information of the corresponding device can be compared with the relationship between the above electrical parameters and the junction temperature of the device to obtain the junction temperature of the silicon carbide MOSFET device.

[0029] Embodiment 2: Figure 2 As shown, this embodiment discloses an online monitoring system for junction temperature of a silicon carbide MOSFET device, including a silicon carbide MOSFET device, a dynamic current information conversion unit, a pulse width counting unit, a high-precision edge positioning unit, and a device junction temperature conversion unit; through the source parasitic inductance of the silicon carbide MOSFET device L SS Convert dynamic current information into induced voltage signal V sense .

[0030] like Figure 3 As shown, the dynamic current information conversion unit is electrically connected to the silicon carbide MOSFET device, and the voltage signal is converted into V sense Converted into a voltage pulse signal containing the on / off delay time and on / off current slope information V CP1 , V CP2 , V CP3 and V CP4 and sends the voltage pulse signal to the pulse width calculation unit and the high-precision edge positioning unit respectively.

[0031] The voltage waveform of the specific dynamic current conversion unit is as follows: Figure 4 As shown, the hardware circuit includes two limiters K 1 , K 2 , two operational amplifiers OP 1 and OP2 , four comparators CP 1 , CP 2 , CP 3 and CP 4 , four resistors R 1 , R 2 , R 3 and R 4 ; Said S 2 The voltage signal in V sense , first through OP 1 , R 1 and R 2 The reverse follower composed of OP 2 , R 3 and R 4 The forward follower composed of V sense The mirror voltage V sense_n and V sense_p ;Mirror voltage V sense_n and V sense_p Voltage limiter K 1 and K 2 After that, you can get a voltage signal that only retains the forward voltage V s_n as well as V s_p ; The voltage signal V s_n The device turn-on delay and current slope information are included and input to the comparator CP 1 , CP 2 The voltage signal can be V s_n The device turn-on delay and current slope information contained in the V CP1 and VCP2 ; The voltage signal V s_p The device shutdown delay and current slope information are included in the comparator CP 3 , CP 4 The voltage signal can be V s_p The device shutdown delay information and current slope information contained in the V CP3 as well as V CP4 .

[0032] The comparator CP 1 , CP 3 Comparison reference voltage V ref1 and V ref3 It should be set to a lower level within the settable range. For example, if the settable range is 0~5V, the reference voltage should be V ref1 and V ref3 , set at 0.3V to quickly trigger the comparator action; The comparator CP 2 , CP 4 Comparison reference voltage V ref2 and V ref4 It should be set to a higher level within the settable range and should be greater than the reference voltage V ref1 and V ref3 If the settable range is 0~5V, the reference voltage should be V ref2 and V ref4 , set above 3.5V so that the current slope information can be extracted as accurately as possible.

[0033] Further, such as Figure 5 , which is a schematic diagram of the time composition between edges to be measured in an embodiment of the present invention. T coarse The fine time around the edge to be measured is obtained by the pulse width calculation unit T fine Obtained by a high-precision edge positioning unit.

[0034] The pulse width counting unit and the high-precision edge positioning unit are electrically connected to the dynamic current information conversion unit, and the rising edge / falling edge of the PWM signal and the voltage pulse signal are extracted through the pulse width calculation unit. V CP1 , V CP2 , V CP3 and V CP4 Rough time between rising edges T coarse ; Use high-precision edge positioning unit to locate the rising / falling edge of PWM signals and voltage pulse signals V CP1 , V CP2 , V CP3 and V CP4 rising edge and calculates the fine time between the above edge and the adjacent clock signal rising edge T fine ; Specifically, the time between the edges of two input signals can be roughly calculated. The implementation of the rough time calculation is mainly based on the counting of the external clock signal. That is, when the input signal has a starting edge, the rising edge of the clock signal starts counting, and when the input signal has an ending edge, the counting ends, and the count value is saved. N cnt . Set the count value N cnt With clock cycle T cycle Multiplying by , we can get the rough time between edges T coarse ; Among them, the rising edge of the PWM signal and the voltage pulse signal V CP1 The approximate time between rising edges is T coarse_01 ; Voltage pulse signal V CP1 Rising edge and voltage pulse signal V CP2 The approximate time between rising edges is T coarse_12 ; PWM signal falling edge and voltage pulse signal V CP3 The approximate time between rising edges is T coarse_34 ; Voltage pulse signal V CP3 Rising edge and voltage pulse signal VCP4 The approximate time between rising edges is T coarse_45 .

[0035] Furthermore, the structure of the high-precision edge positioning unit in the embodiment of the present invention is as follows: Figure 6 As shown, its structure contains N Delay units, N indivual D Triggers and N registers, each of which corresponds to a delay unit D a flip-flop and a register; The N Delay cells have consistent delay times T delay , and these delay units are connected in sequence to form a delay chain, which can generate N The pulse widths of the two paths are the same and the phases are delayed successively. T delay The pulse signal is sent to the corresponding D In trigger; The N indivual D The trigger latches the state of the input pulse signal at each rising edge of the external clock and saves it to the corresponding register. N The number of "1"s in a register determines the position of the measured edge within the clock cycle.

[0036] The statistics of N A method for determining the position of a measured edge in a clock cycle by the number of "1"s in a register, characterized in that in the next clock cycle of the located pulse edge, the high-precision edge positioning unit counts N The number of "1"s in a register is N cnt_fine and multiply it by T delay The precise time between the edge to be measured and the rising edge of the clock can be obtained T fine .

[0037] Among them, the fine time at the rising edge of the PWM signal is T fine_rising ; Voltage pulse signal V CP1 The fine time at the rising edge is T fine_1 ; Voltage pulse signal V CP2 The fine time at the rising edge is Tfine_2 ; The fine time at the falling edge of the PWM signal is T fine_falling ; Voltage pulse signal V CP3 The fine time at the rising edge is T fine_4 ; Voltage pulse signal V CP4 The fine time at the rising edge is T fine_5 .

[0038] Further, the steps for obtaining the junction temperature of the silicon carbide MOSFET device are as follows: S 5 , characterized in that the rising edge of the PWM signal and the voltage pulse signal V CP1 Time between rising edges T t0-t1 , voltage pulse signal V CP1 Rising edge and voltage pulse signal V CP2 Time between rising edges T t1-t2 , PWM signal falling edge and voltage pulse signal V CP3 Time between rising edges T t3-t4 And voltage pulse signal V CP3 Rising edge and voltage pulse signal V CP4 Time between rising edges T t4-t5 It can be calculated according to the following formula:

[0039] The above pulse time can correspond to the turn-on / off delay time and turn-on / off current slope information of the silicon carbide MOSFET device. T t0-t1 Corresponding opening delay time; T t1-t2 Corresponding turn-on current slope information; T t3-t4 Corresponding shutdown delay time; T t4-t5 Corresponding shutdown current slope information.

[0040] The device junction temperature conversion unit is electrically connected to the dynamic current information conversion unit and the pulse width counting unit. The device junction temperature conversion unit converts the corresponding rough time obtained in the pulse width calculation unit into Tcoarse , and the corresponding fine time obtained in the high-precision edge positioning unit T fine By adding them together, we can get the accurate turn-on / turn-off delay time and turn-on / turn-off current slope information of the device. Finally, by comparing the relationship between the above parameters and the junction temperature of the device, we can get the junction temperature of the device.

[0041] The above junction temperature monitoring solution is used in Figure 7 In the silicon carbide MOSFET drive structure test platform shown in the figure, the programmable logic chip used in the driver is ZYNQ-7010, which finally realizes T t0-t1 , T t0-t1 , T t0-t1 and T t0-t1 The detection accuracy of temperature-sensitive electrical parameters such as electrical parameters is 70 picoseconds resolution.

[0042] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made on the basis and within the scope of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for online monitoring of junction temperature of a silicon carbide MOSFET device, characterized in that: The steps include: Convert dynamic current information into induced voltage signal V sense ; The induced voltage signal V sense Converted into a voltage pulse signal containing the on / off delay time and on / off current slope information V CP1 , V CP2 , V CP3 and V CP4 ; Extract PWM signal rising edge / falling edge and voltage pulse signal V CP1 , V CP2 , V CP3 and V CP4 Rough time between rising edges T coarse ; Positioning PWM signal rising edge / falling edge, voltage pulse signal V CP1 , V CP2 , V CP3 and V CP4 rising edge and calculates the fine time between the above edge and the adjacent clock signal rising edge T fine ; The rough time T coarse With fine time T fine By superimposing them, the precise turn-on / turn-off delay time and turn-on / turn-off current slope information of the device are obtained, and the device junction temperature is obtained by comparing the relationship between the turn-on / turn-off delay time and turn-on / turn-off current slope information and the device junction temperature.

2. The method for online monitoring junction temperature of a silicon carbide MOSFET device according to claim 1, characterized in that: Induced voltage signal V sense Converted into voltage pulse signal V CP1 , V CP2 , V CP3 and V CP4 The process includes the following steps: Based on the induced voltage signal V sense Get its mirror voltage V sense_n and V sense_p ; Mirror voltage V sense_n and V sense_p Perform voltage limiting to obtain a voltage signal that only retains the forward voltage V s_n and V s_p ; Will V s_n The device turn-on delay and current slope information contained in the V CP1 and V CP2 ; V s_p The device shutdown delay information and current slope information contained in the V CP3 as well as V CP4 .

3. The method for online monitoring junction temperature of a silicon carbide MOSFET device according to claim 1, characterized in that: Rough time T coarse The extraction includes: When the input signal has a starting edge, the rising edge of the clock signal starts counting, and when the input signal has an ending edge, the counting ends and the count value is saved. N cnt , the count value N cnt With clock cycle T cycle Multiplying by , we can get the rough time between edges T coarse .

4. The method for online monitoring junction temperature of a silicon carbide MOSFET device according to claim 1 or 3, characterized in that: The approximate time T coarse include: PWM signal rising edge and voltage pulse signal V CP1 The approximate time between rising edges is T coarse_01 ; Voltage pulse signal V CP1 Rising edge and voltage pulse signal V CP2 The approximate time between rising edges is T coarse_12 ; PWM signal falling edge and voltage pulse signal V CP3 The approximate time between rising edges is T coarse_34 ; Voltage pulse signal V CP3 Rising edge and voltage pulse signal V CP4 The approximate time between rising edges is T coarse_45 .

5. The method for online monitoring junction temperature of a silicon carbide MOSFET device according to claim 3, characterized in that: Fine Time T fine The calculation includes: Count the number of input pulse signals N cnt_fine and multiply it by T delay The precise time between the edge to be measured and the rising edge of the clock can be obtained T fine .

6. The method for online monitoring junction temperature of a silicon carbide MOSFET device according to claim 1 or 5, characterized in that: The fine time T fine include: The fine time at the rising edge of the PWM signal is T fine_rising ; Voltage pulse signal V CP1 The fine time at the rising edge is T fine_1 ; Voltage pulse signal V CP2 The fine time at the rising edge is T fine_2 ; The fine time at the falling edge of the PWM signal is T fine_falling ; Voltage pulse signal V CP3 The fine time at the rising edge is T fine_4 ; Voltage pulse signal V CP4 The fine time at the rising edge is T fine_5 .

7. The method for online monitoring junction temperature of a silicon carbide MOSFET device according to claim 1, characterized in that: PWM signal rising edge and voltage pulse signal V CP1 Time between rising edges T t0-t1 , T t0-t1 The turn-on delay time of the corresponding device; Voltage pulse signal V CP1 Rising edge and voltage pulse signal V CP2 Time between rising edges T t1-t2 , T t1-t2 The turn-on current slope information of the corresponding device; PWM signal falling edge and voltage pulse signal V CP3 Time between rising edges T t3-t4 ; T t3-t4 The turn-off delay time of the corresponding device; Voltage pulse signal V CP3 Rising edge and voltage pulse signal V CP4 Time between rising edges T t4-t5 ; T t4-t5 The corresponding device's shutdown current slope information.

8. An online monitoring system for junction temperature of a silicon carbide MOSFET device, characterized in that: It includes silicon carbide MOSFET devices, dynamic current information conversion unit, pulse width counting unit, high-precision edge positioning unit and device junction temperature conversion unit; The dynamic current information conversion unit is electrically connected to the silicon carbide MOSFET device and is used to convert the induced voltage signal V sense Converted into a voltage pulse signal containing the on / off delay time and on / off current slope information V CP1 , V CP2 , V CP3 and V CP4 ; The pulse width counting unit and the high-precision edge positioning unit are electrically connected to the dynamic current information conversion unit. The pulse width counting unit extracts the rising edge / falling edge of the PWM signal and the voltage pulse signal. V CP1 , V CP2 , V CP3 and V CP4 Rough time between rising edges T coarse The high-precision edge positioning unit is used to locate the rising edge / falling edge of the PWM signal and the voltage pulse signal V CP1 , V CP2 , V CP3 and V CP4 rising edge and calculates the fine time between the above edge and the adjacent clock signal rising edge T fine ; The device junction temperature conversion unit is electrically connected to the dynamic current information conversion unit and the pulse width counting unit, and is used to convert the corresponding rough time obtained in the pulse width calculation unit into T coarse , and the corresponding fine time obtained in the high-precision edge positioning unit T fine By superimposing them, the precise turn-on / turn-off delay time and turn-on / turn-off current slope information of the device can be obtained.

9. The online monitoring system for junction temperature of a silicon carbide MOSFET device according to claim 8, characterized in that: The device also includes a reverse follower, a forward follower and a voltage limiter which are electrically connected, wherein the reverse follower and the forward follower are used to obtain an induced voltage signal. V sense The mirror voltage V sense_n and V sense_p , the voltage limiter is used based on the mirror voltage V sense_n and V sense_p Obtain a voltage signal that retains only the forward voltage V s_n as well as V s_p .

10. The online monitoring system for junction temperature of a silicon carbide MOSFET device according to claim 8, characterized in that: The high-precision edge positioning unit includes a delay unit, a trigger and a register, each delay unit corresponds to a trigger and a register, and the delay unit has a delay time T delay The trigger is used to latch the state of the input pulse signal at each rising edge of the external clock and save it in the corresponding register.

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