An on-line monitoring method and system for the junction temperature of a silicon carbide MOSFET device

Abstract

The present invention belongs to the field of power device state detection, and relates to an online monitoring method and system for junction temperature of a silicon carbide MOSFET device, which converts dynamic current information into an 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 ; Locate 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, so as to realize the online extraction of the junction temperature.

Description

Technical Field

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

[0002] The wide 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, silicon carbide devices with fast turn-on 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 in power electronics at this stage. The junction temperature of a device is a key parameter that can reflect the operating state of the device. How to achieve its online monitoring is one of the bases for the protection and health detection of silicon carbide devices.

[0003] The device junction temperature monitoring method based on thermosensitive electrical parameters has received extensive attention due to its non-invasive and online characteristics. However, with the popular application of wide bandgap materials such as silicon carbide and gallium nitride in semiconductor devices, the sensitivity of the electrical parameters of the device to the junction temperature has also decreased, which makes it more difficult to implement the device junction temperature monitoring based on thermosensitive electrical parameters.

[0004] Therefore, there is an urgent need to propose an online monitoring scheme for the junction temperature of a silicon carbide MOSFET device to solve the above problems. Summary of the Invention

[0005] The present invention discloses a method and system for online monitoring of the junction temperature of a silicon carbide MOSFET device, mainly solving the problem of difficult monitoring of the junction temperature of a device based on thermosensitive electrical parameters.

[0006] To achieve the above object, the present invention provides a method for online monitoring of the junction temperature of a silicon carbide MOSFET device, including the following steps:

[0007] Converting dynamic current information into an induced voltage signal V sense ;

[0008] Converting the induced voltage signal V sense into a voltage pulse signal containing turn-on / turn-off delay time, turn-on / turn-off current slope information V CP1 , V CP2 , V CP3 and V CP4 ;

[0009] Extracting the rising edge / falling edge of the PWM signal and the voltage pulse signal V CP1 ,V CP2 , V CP3 and V CP4 The rough time between rising edges T coarse ;

[0010] Locate the rising / falling edges of the PWM signal and the voltage pulse signal V CP1 , V CP2 , V CP3 and V CP4 rising edges, and calculate the fine time between the above-mentioned edges and the rising edge of the adjacent clock signal T fine ;

[0011] Add the rough time T coarse to the fine time T fine to obtain the accurate turn-on / turn-off delay time of the device and the turn-on / turn-off current slope information, and obtain the device junction temperature by comparing the relationship between the turn-on / turn-off delay time and the turn-on / turn-off current slope information and the device junction temperature.

[0012] Further, the induced voltage signal V sense is converted into a voltage pulse signal V CP1 , V CP2 , V CP3 and V CP4 The process includes the following steps:

[0013] Based on the induced voltage signal V sense obtain its mirror voltage V sense_n and V sense_p ;

[0014] Perform voltage limiting on the mirror voltages V sense_n and V sense_p to obtain voltage signals V s_n and V s_p that only retain the forward voltage;

[0015] Add Vs_n The device turn-on delay and current slope information contained therein are converted into pulse information V CP1 and V CP2 ; V s_p The device turn-off delay information and current slope information contained therein are converted into pulse information V CP3 and V CP4 .

[0016] Furthermore, the extraction of the rough time T coarse includes:

[0017] Start counting the rising edge of the clock signal when the start edge of the input signal appears, end counting when the end edge of the input signal appears, and save the count value N cnt , multiply the count value N cnt by the clock period T cycle to obtain the rough time between the edges T coarse .

[0018] Furthermore, the rough time T coarse includes:

[0019] The rough time between the rising edge of the PWM signal and the rising edge of the voltage pulse signal V CP1 is T coarse_01 ;

[0020] The rough time between the rising edge of the voltage pulse signal V CP1 and the rising edge of the voltage pulse signal V CP2 is T coarse_12 ;

[0021] The rough time between the falling edge of the PWM signal and the rising edge of the voltage pulse signal V CP3 is T coarse_34 ;

[0022] The rough time between the rising edge of the voltage pulse signal V CP3 and the rising edge of the voltage pulse signal V CP4 is Tcoarse_45 。

[0023] Furthermore, the calculation of the fine time T fine includes:

[0024] Count the number of input pulse signals N cnt_fine , and multiply it by T delay to obtain the fine time between the edge to be measured and the rising edge of the clock T fine 。

[0025] Furthermore, the fine time T fine includes:

[0026] The fine time at the rising edge of the PWM signal is T fine_rising ;

[0027] The voltage pulse signal V CP1 The fine time at the rising edge is T fine_1 ;

[0028] The voltage pulse signal V CP2 The fine time at the rising edge is T fine_2 ;

[0029] The fine time at the falling edge of the PWM signal is T fine_falling ;

[0030] The voltage pulse signal V CP3 The fine time at the rising edge is T fine_4 ;

[0031] The voltage pulse signal V CP4 The fine time at the rising edge is T fine_5 。

[0032] Furthermore, the time V CP1 between the rising edge of the PWM signal and the rising edge of the voltage pulse signal T t0-t1 , T t0-t1 corresponds to the turn-on delay time of the corresponding device;

[0033] The voltage pulse signal VCP1 Rising edge and voltage pulse signal V CP2 Time between rising edges T t1-t2 , T t1-t2 Turn-on current slope information of the corresponding device;

[0034] Time between the falling edge of the PWM signal and the rising edge of the voltage pulse signal V CP3 Time between rising edges T t3-t4 ; T t3-t4 Turn-off delay time of the corresponding device;

[0035] Voltage pulse signal V CP3 Time between the rising edge of the voltage pulse signal and the rising edge of the voltage pulse signal V CP4 Time between rising edges T t4-t5 ; T t4-t5 Turn-off current slope information of the corresponding device.

[0036] The present invention also provides an on-line monitoring system for the 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;

[0037] 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 into a voltage pulse signal containing turn-on / turn-off delay time, turn-on / turn-off current slope information V CP1 , V CP2 , V CP3 and V CP4 ;

[0038] 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 rough time between the rising edge / falling edge of the PWM signal and the rising edge of the voltage pulse signal V CP1 , V CP2 , V CP3 and V CP4 Time between rising edges Tcoarse ; 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 calculate the fine time between the above-mentioned edge and the rising edge of the adjacent clock signal T fine ;

[0039] 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 T coarse , and the corresponding fine time obtained in the high-precision edge positioning unit T fine are superimposed to obtain the accurate turn-on / turn-off delay time of the device and the turn-on / turn-off current slope information.

[0040] Furthermore, it also includes an electrically connected reverse follower, a forward follower, and a voltage limiter. The reverse follower and the forward follower are used to obtain the mirror voltage V sense of the induced voltage signal V sense_n and V sense_p , and the voltage limiter is used to obtain a voltage signal that only retains the positive voltage based on the mirror voltage V sense_n and V sense_p V s_n and V s_p .

[0041] 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 to the corresponding register.

[0042] The technical solution provided by the present invention has at least the following technical effects:

[0043] 1. The present invention utilizes the parasitic inductance of the silicon carbide MOSFET device itself L SS ​, and a simple comparison circuit can be used to extract electrical parameters such as the device turn-on / turn-off delay time and the turn-on / turn-off current slope.

[0044] 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 the programmable logic chip, having good portability and facilitating the online extraction of the junction temperature.

[0045] 3. The present invention can achieve high-precision identification of the pulse width (identification with picosecond-level precision). During the process of junction temperature extraction, it is not necessary to amplify the thermoelectric parameters of the silicon carbide MOSFET device, and it is not necessary to disrupt the normal operating conditions of the power electronic equipment, which is beneficial to improving the reliability of the converter operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0047] The drawings constituting a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation to this application. In the drawings:

[0048] Figure 1 is a flowchart of the method for online monitoring of the junction temperature of the silicon carbide MOSFET device in the embodiment of the present invention;

[0049] Figure 2 is a structural diagram of the system for online monitoring of the junction temperature of the silicon carbide MOSFET device in the embodiment of the present invention;

[0050] Figure 3 is a schematic structural diagram of the dynamic current information conversion unit in the embodiment of the present invention;

[0051] Figure 4 is a waveform diagram of the dynamic current information conversion unit in the embodiment of the present invention;

[0052] Figure 5 is a schematic diagram of the time composition between the edges to be measured in the embodiment of the present invention;

[0053] Figure 6 is a schematic structural diagram of the high-precision edge positioning unit in the embodiment of the present invention;

[0054] Figure 7 is the drive test platform of the silicon carbide MOSFET device used in the embodiment of the present invention. Detailed implementation manners

[0055] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, in which the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the embodiments of the present invention, and should not be construed as limiting the present invention.

[0056] Embodiment 1: As Figure 1 shown, this embodiment discloses an on-line monitoring method for the junction temperature of a silicon carbide MOSFET device, mainly solving the problem of difficult junction temperature monitoring of devices based on thermosensitive electrical parameters. The method includes the following steps:

[0057] S 1 : Convert the dynamic current information into an induced voltage signal through the source parasitic inductance of the silicon carbide MOSFET device L SS ; V sense；

[0058] S 2 : Convert the voltage signal through a dynamic current conversion unit V sense into a voltage pulse signal containing turn-on / turn-off delay time, turn-on / turn-off current slope information V CP1 、 V CP2 、 V CP3 and V CP4 , and send the above voltage pulse signals to a pulse width calculation unit and a high-precision edge positioning unit respectively; specifically, based on the induced voltage signal V sense obtain its mirror voltages V sense_n and V sense_p ; Perform voltage limiting on the mirror voltages V sense_n and V sense_p to obtain voltage signals V s_n and V s_p that only retain the forward voltage; V s_n Convert the device turn-on delay and current slope information included in V CP1 and V CP2; V s_p Convert the device turn-off delay information and current slope information contained therein into pulse information V CP3 and V CP4 .

[0059] S 3 : Through the pulse width calculation unit, extract the rough time between the rising edge / falling edge of the PWM signal and the rising edges of the voltage pulse signals V CP1 , V CP2 , V CP3 and V CP4 the rising edges. Specifically, start counting the rising edge of the clock signal when the start edge of the input signal appears, end counting when the end edge of the input signal appears, and save the count value T coarse . Multiply the count value N cnt by the clock period N cnt to obtain the rough time between the edges T cycle ; T coarse ;

[0060] The rough time T coarse includes:

[0061] The rough time between the rising edge of the PWM signal and the rising edge of the voltage pulse signal V CP1 is T coarse_01 ;

[0062] The voltage pulse signal V CP1 The rough time between the rising edge of the voltage pulse signal and the rising edge of the voltage pulse signal V CP2 is T coarse_12 ;

[0063] The rough time between the falling edge of the PWM signal and the rising edge of the voltage pulse signal V CP3 is T coarse_34 ;

[0064] The voltage pulse signal V CP3 The rough time between the rising edge of the voltage pulse signal and the rising edge of the voltage pulse signalV CP4 The rough time between rising edges is T coarse_45 .

[0065] S 4 : By means of a high-precision edge positioning unit, position the rising / falling edges of the PWM signal, voltage pulse signals V CP1 , V CP2 , V CP3 and V CP4 rising edges, and calculate the fine time between the above-mentioned edges and the rising edge of the adjacent clock signal T fine ;

[0066] Specifically, count the number of input pulse signals N cnt_fine , and multiply it by T delay to obtain the fine time between the edge to be measured and the rising edge of the clock T fine .

[0067] Furthermore, the fine time T fine includes:

[0068] The fine time at the rising edge of the PWM signal is T fine_rising ;

[0069] The voltage pulse signal V CP1 The fine time at the rising edge is T fine_1 ;

[0070] The voltage pulse signal V CP2 The fine time at the rising edge is T fine_2 ;

[0071] The fine time at the falling edge of the PWM signal is T fine_falling ;

[0072] The voltage pulse signal V CP3 The fine time at the rising edge is T fine_4 ;

[0073] The voltage pulse signal V CP4The fine time at the rising edge is T fine_5 .

[0074] S 5 : The device junction temperature conversion unit adds the corresponding rough time obtained in the pulse width calculation unit T coarse , with the corresponding fine time obtained in the high-precision edge positioning unit T fine . Then the accurate turn-on / off delay time and turn-on / off current slope information of the device can be obtained. Finally, the device junction temperature can be obtained by referring to the relationship between the above parameters and the device junction temperature.

[0075] The time between the rising edge of the PWM signal and the rising edge of the voltage pulse signal V CP1 , T t0-t1 , T t0-t1 corresponds to the turn-on delay time of the device;

[0076] The time between the rising edge of the voltage pulse signal V CP1 and the rising edge of the voltage pulse signal V CP2 , T t1-t2 , T t1-t2 corresponds to the turn-on current slope information of the device;

[0077] The time between the falling edge of the PWM signal and the rising edge of the voltage pulse signal V CP3 ; T t3-t4 ; T t3-t4 corresponds to the turn-off delay time of the device;

[0078] The time between the rising edge of the voltage pulse signal V CP3 and the rising edge of the voltage pulse signal V CP4 ; T t4-t5 ; T t4-t5 corresponds to the turn-off current slope information of the device. By referring to the relationship between the above electrical parameters and the device junction temperature, the junction temperature of the silicon carbide MOSFET device can be obtained.

[0079] Example 2: As Figure 2As shown, this embodiment discloses an on-line monitoring system for the 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 the dynamic current information into an induced voltage signal V sense .

[0080] As Figure 3 shown, the dynamic current information conversion unit is electrically connected to the silicon carbide MOSFET device, and the voltage signal V sense is converted into a voltage pulse signal containing turn-on / turn-off delay time, turn-on / turn-off current slope information V CP1 , V CP2 , V CP3 and V CP4 , and the above voltage pulse signals are respectively sent to the pulse width calculation unit and the high-precision edge positioning unit.

[0081] The specific voltage waveform of the dynamic current conversion unit is as Figure 4 shown, where the hardware circuit includes two limiters K 1 , K 2 , two operational amplifiers OP 1 and OP 2 , four comparators CP 1 , CP 2 , CP 3 and CP 4 , four resistors R 1 , R 2 , R 3 and R 4 ;

[0082] The S 2 voltage signal in V sense , first passes through OP 1 ,R 1 and R 2 form a negative follower, and OP 2 、 R 3 and R 4 form a positive follower, which can obtain V sense the mirror voltage V sense_n and V sense_p ; The mirror voltage V sense_n and V sense_p respectively pass through the voltage limiters K 1 and K 2 to obtain a voltage signal with only the positive voltage remaining V s_n and V s_p ;

[0083] The voltage signal V s_n contains device turn-on delay and current slope information. Inputting it into the comparators CP 1 、 CP 2 can convert the device turn-on delay and current slope information contained in the voltage signal V s_n into pulse information V CP1 and V CP2 ;

[0084] The voltage signal V s_p contains device turn-off delay and current slope information. Inputting it into the comparators CP 3 、 CP 4 can convert the device turn-off delay information and current slope information contained in the voltage signal V s_p into pulse information V CP3 and V CP4 .

[0085] The comparators CP 1 、CP 3 The comparison reference voltage V ref1 and V ref3 should be set at a lower level within the settable range. For example, in the settable range of 0~5V, the reference voltage V ref1 and V ref3 , should be set at 0.3V so as to be able to quickly trigger the comparator action;

[0086] The comparator CP 2 、 CP 4 The comparison reference voltage V ref2 and V ref4 should be set at a higher level within the settable range and should be greater than the reference voltage V ref1 and V ref3 . For example, in the settable range of 0~5V, the reference voltage V ref2 and V ref4 , should be set above 3.5V so as to be able to extract the current slope information as accurately as possible.

[0087] Furthermore, as Figure 5 shown, it is a schematic diagram of the time composition between the edges to be measured in the embodiment of the present invention. Among them, the rough time between the edges to be measured T coarse is obtained by the pulse width calculation unit, and the fine time near the edge to be measured T fine is obtained by the high-precision edge positioning unit.

[0088] The pulse width counting unit and the high-precision edge positioning unit are electrically connected to the dynamic current information conversion unit. Through the pulse width calculation unit, the rough time between the rising edge / falling edge of the PWM signal and the voltage pulse signals V CP1 、 V CP2 、 V CP3 and V CP4 rising edges is extracted; through the high-precision edge positioning unit, the rising edge / falling edge of the PWM signal, the voltage pulse signals T coarse ; through the high-precision edge positioning unit, the rising edge / falling edge of the PWM signal, the voltage pulse signals V CP1 、 VCP2 , V CP3 and V CP4 rising edges, and calculate the fine time between the above-mentioned edges and the rising edges of the adjacent clock signals T fine ;

[0089] Specifically, the time between the edges of the 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 start edge of the input signal appears, the counting of the rising edge of the clock signal starts, and when the end edge of the input signal appears, the counting ends, and the count value is saved N cnt . Multiply the count value N cnt by the clock period T cycle to obtain the rough time between the edges T coarse ;

[0090] Among them, the rough time between the rising edge of the PWM signal and the rising edge of the voltage pulse signal V CP1 is T coarse_01 ; the rough time between the rising edge of the voltage pulse signal V CP1 and the rising edge of the voltage pulse signal V CP2 is T coarse_12 ; the rough time between the falling edge of the PWM signal and the rising edge of the voltage pulse signal V CP3 is T coarse_34 ; the rough time between the rising edge of the voltage pulse signal V CP3 and the rising edge of the voltage pulse signal V CP4 is T coarse_45 .

[0091] Further, the structure of the high-precision edge positioning unit in the embodiment of the present invention is as shown in Figure 6 , and its internal structure includes N delay units, N D flip-flops, and N registers, where each delay unit corresponds to one D flip-flop and one register;

[0092] The described NThe delay units have consistent delay times T delay , and these delay units are connected in sequence to form a delay chain, which can generate N pulses with the same pulse width and successively delayed phases T delay , and are sent to the corresponding D flip - flops;

[0093] For the N number of D flip - flops mentioned above, at each rising edge of the external clock, they latch the state of the input pulse signal and save it to the corresponding register. Finally, by counting the number of "1"s inside the N number of registers, the position of the measured edge within the clock cycle is determined.

[0094] For the method of determining the position of the measured edge within the clock cycle by counting the number of "1"s inside the N number of registers, its feature is that in the next clock cycle after the edge of the pulse to be located, the high - precision edge positioning unit counts the number of "1"s in the N number of registers as N cnt_fine , and multiplies it by T delay to obtain the fine time between the edge to be measured and the rising edge of the clock T fine .

[0095] Among them, the fine time at the rising edge of the PWM signal is T fine_rising ; the fine time at the rising edge of the voltage pulse signal V CP1 is T fine_1 ; the fine time at the rising edge of the voltage pulse signal V CP2 is T fine_2 ; the fine time at the falling edge of the PWM signal is T fine_falling ; the fine time at the rising edge of the voltage pulse signal V CP3 is T fine_4 ; the fine time at the rising edge of the voltage pulse signal V CP4 is T fine_5 .

[0096] Furthermore, for the steps of obtaining the junction temperature of the silicon carbide MOSFET device S5 , characterized in that the time between the rising edge of the PWM signal and the rising edge of the voltage pulse signal V CP1 、the time between the rising edge of the voltage pulse signal T t0-t1 、the rising edge of the voltage pulse signal V CP1 、the time between the rising edge of the voltage pulse signal and the rising edge of the voltage pulse signal V CP2 、the time between the falling edge of the PWM signal and the rising edge of the voltage pulse signal T t1-t2 、and the time between the rising edge of the voltage pulse signal and the rising edge of the voltage pulse signal V CP3 can be calculated according to the following formula: T t3-t4 The above pulse time can correspond to the turn-on / turn-off delay time and turn-on / turn-off current slope information of the silicon carbide MOSFET device. Among them, V CP3 corresponds to the turn-on delay time; V CP4 corresponds to the turn-on current slope information; T t4-t5 corresponds to the turn-off delay time;

[0097]

[0098] corresponds to the turn-off current slope information. T t0-t1 corresponds to the turn-on delay time; T t1-t2 corresponds to the turn-on current slope information; T t3-t4 corresponds to the turn-off delay time; T t4-t5 corresponds to the turn-off current slope information.

[0099] 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 combines the corresponding rough time obtained from the pulse width calculation unit T coarse with the corresponding fine time obtained from the high-precision edge positioning unit T fine to obtain the accurate turn-on / turn-off delay time and turn-on / turn-off current slope information of the device. Finally, the device junction temperature can be obtained by referring to the relationship between the above parameters and the device junction temperature.

[0100] The above junction temperature monitoring scheme is applied to the silicon carbide MOSFET drive structure test platform shown in Figure 7 . Among them, the programmable logic chip used by the driver is ZYNQ-7010, and finally Tt0-t1 , T t0-t1 , T t0-t1 and T t0-t1 The detection accuracy of the electrical parameter isothermal electrical parameter with a resolution of 70 picoseconds.

[0101] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, and improvements made on the basis and within the scope of the present invention shall be included within 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 rough 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 rough time between rising edges is T coarse_34 ; Voltage pulse signal V CP3 Rising edge and voltage pulse signal V CP4 The rough 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.

Images