A method and system for on-line condition monitoring of SiC MOSFET

Abstract

The present application relates to a kind of SiC MOSFET online condition monitoring method and system, method includes the following steps: in non-contact mode acquisition SiC MOSFET gate loop's switching current oscillation signal, and extract amplitude information for condition monitoring;Obtain the operating parameter information of SiC MOSFET, based on the operating characteristic of the pre-calibrated SiC MOSFET gate high-frequency switching oscillation circuit peak value, the amplitude information is working condition compensation, obtains the compensated gate high-frequency switching oscillation circuit peak value under rated working condition;Based on the gate high-frequency switching oscillation circuit peak value under rated working condition, the degree of device aging is evaluated.Compared with prior art, the present application has the advantages of high sensitivity, high safety and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power semiconductor device monitoring, in particular to a SiC MOSFET online state monitoring method and system. BACKGROUND

[0002] The faster switching speed, lower switching loss and higher temperature resistance of SiC MOSFET make it a development trend of new generation high power density electric energy conversion device. While SiC MOSFET brings a significant performance improvement to the converter, its reliability problem is increasingly concerned. In order to improve the operation reliability of SiC MOSFET, its early degradation state needs to be monitored online. However, due to the extremely fast switching speed of SiC MOSFET (about tens of nanoseconds), the online monitoring of dynamic characteristic parameters (such as switching time, Miller platform time, etc.) requires high time resolution of hardware equipment. Moreover, due to the high frequency operation of SiC MOSFET being sensitive to parasitic parameters, direct measurement of SiC MOSFET voltage through physical contact will introduce additional high frequency parasitic parameter interference, but the existing monitoring method is difficult to achieve non-contact online monitoring without interference.

[0003] FARHADI M et al. in the document "Temperature Independent Gate Oxide Degradation Monitoring of SiC MOSFETs Based on Junction Capacitances" studied the influence of gate oxide aging on SiC MOSFET junction capacitance and designed a state detection method, but the interval in which the junction capacitance is highly sensitive to gate oxide aging does not belong to the normal operating condition of the device. In order to realize online monitoring, a special gate drive circuit needs to be designed to change the switching operating condition.

[0004] PU Shi et al. in the document "In situ Degradation Monitoring of SiC MOSFET Based on Switching Transient Measurement" used the turn-on time of the device as a precursor of aging, and developed a picosecond resolution detection circuit to detect the change of turn-on time. But this monitoring system needs very high sampling accuracy, which is difficult to be used in large scale for industrial application.

[0005] Chinese patent application No. CN202111248678.8 provides a SiC MOSFET device gate aging monitoring circuit and online monitoring method, which can realize online monitoring of gate aging without affecting the normal operation of the device and the device, solves the problem that most gate aging monitoring methods are difficult to implement online, and effectively avoids economic losses caused by shutdown monitoring. The application determines the aging state of the device by changes in parasitic parameters, and needs to set isolation type gate drivers, latches, comparators and other devices, so the hardware structure is relatively complex.

[0006] To overcome the deficiencies of the prior art, the present application provides a SiC MOSFET online state monitoring system and method. SUMMARY

[0007] The purpose of the present application is to provide a SiC MOSFET online state monitoring method and system to overcome the deficiencies of the prior art. The gate high-frequency switching oscillation current is measured in a non-contact manner to realize safe and sensitive online monitoring of the early degradation state of SiC MOSFET.

[0008] The purpose of the present application can be achieved by the following technical solutions:

[0009] In one aspect of the present application, a SiC MOSFET online state monitoring method is provided, comprising the following steps:

[0010] The switching current oscillation signal of the SiC MOSFET gate loop is collected in a non-contact manner, and the amplitude information for state monitoring is extracted;

[0011] The operating parameter information of the SiC MOSFET is obtained, and the amplitude information is compensated for operating conditions based on the operating characteristics of the pre-calibrated peak value of the SiC MOSFET gate high-frequency switching oscillation circuit, to obtain the compensated peak value of the gate high-frequency switching oscillation circuit under the rated operating condition.

[0012] Based on the peak value of the gate high-frequency switching oscillation circuit under the rated operating condition, the degree of device aging is evaluated.

[0013] As a preferred technical solution, based on the switching current oscillation signal, the amplitude information for state monitoring is obtained by high-frequency peak detection and signal sampling.

[0014] As a preferred technical solution, the operating parameter information includes at least one of DC voltage, current and temperature.

[0015] As a preferred technical solution, the evaluation of the degree of device aging is specifically:

[0016] By comparing the peak value of the gate high-frequency switching oscillation circuit obtained in this measurement with the historical measurement gate high-frequency switching oscillation circuit peak value, the degree of device aging is quantitatively evaluated.

[0017] As a preferred technical solution, the switching current oscillation signal is collected from the SiC MOSFET gate loop by a non-contact high-frequency switching current oscillation sensor.

[0018] As a preferred technical solution, the bandwidth of the high-frequency switching current oscillation sensor is 1MHz-30MHz.

[0019] Another aspect of the present application provides a SiC MOSFET online state monitoring system, comprising:

[0020] The gate high-frequency switching current oscillation capture module comprises a high-frequency oscillation circuit sensor arranged in the SiC MOSFET gate loop, which is used to capture the switching current oscillation signal in a non-contact manner online;

[0021] The oscillation amplitude feature extraction module is used to take out the amplitude information for SiC MOSFET state monitoring based on the switching current oscillation signal;

[0022] The operating condition compensation module is used to collect operating parameter information, and compensate the amplitude information based on the operating characteristics of the pre-calibrated SiC MOSFET gate high-frequency switching oscillation circuit peak value, to obtain the compensated gate high-frequency switching oscillation circuit peak value under the rated operating condition;

[0023] The aging state evaluation module is used to quantitatively evaluate the degree of device aging based on the gate high-frequency switching oscillation circuit peak value under the rated operating condition.

[0024] As a preferred technical solution, the oscillation amplitude feature extraction module comprises a high-frequency peak detection analog circuit and a signal sampling digital circuit.

[0025] Another aspect of the present application provides an electronic device, comprising one or more processors and a memory, the memory storing one or more programs, the one or more programs comprising instructions for executing the above-mentioned SiC MOSFET online state monitoring method.

[0026] Another aspect of the present application provides a computer-readable storage medium comprising one or more programs for execution by one or more processors of an electronic device, the one or more programs comprising instructions for executing the above-mentioned SiC MOSFET online state monitoring method.

[0027] Compared with the prior art, the present application has the following advantages:

[0028] (1)High sensitivity: the application measures the gate high-frequency switching oscillation current by non-contact method, extracts amplitude information and realizes state monitoring through working condition compensation, the gate high-frequency switching oscillation is more sensitive to the health state of SiC MOSFET, for example, the gate high-frequency switching oscillation peak of SiC MOSFET gate oxide aging will gradually decrease, and the decrease amplitude is more than 20%, therefore, the scheme of the application has higher sensitivity.

[0029] (2)High safety: the non-contact sensor is used to measure and capture the gate high-frequency switching oscillation current online, and does not affect the normal operation of SiC MOSFET, so that safe and continuous online monitoring can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 SiC MOSFET online state monitoring system block diagram;

[0031] Figure 2 Gate high-frequency oscillation current sensor installation position;

[0032] Figure 3 SiC MOSFET online state monitoring method flow chart;

[0033] Figure 4 SiC MOSFET gate oxide aging state monitoring experimental system principle diagram;

[0034] Figure 5 Gate high-frequency switching oscillation current sensor and high-frequency peak detection circuit physical diagram;

[0035] Figure 6 Gate current oscillation i g-s under different gate oxide aging time;

[0036] Figure 7 Peak detection circuit output signal;

[0037] Figure 8 i g-s peak and gate oxide aging relationship diagram,

[0038] 1, gate high-frequency switching current oscillation capture module, 2, oscillation amplitude feature extraction module, 3, running condition compensation module, 4, aging state evaluation module. DETAILED DESCRIPTION

[0039] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be clearly and completely described below, obviously, the described embodiments are a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work should belong to the protection scope of the present application.

[0040] Embodiment 1

[0041] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be clearly and completely described below, obviously, the described embodiments are a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work should belong to the protection scope of the present application. Figure 1 , the present embodiment provides a SiC MOSFET online state monitoring system, which measures and compares the peak state information of the gate oscillation. The block diagram of the SiC MOSFET online state monitoring system is shown in Figure 1 .

[0042] The SiC MOSFET online state monitoring system mainly includes four modules: a gate high-frequency switching current oscillation capture module, an oscillation amplitude feature extraction module, a running condition compensation module, and an aging state evaluation module.

[0043] (1) Gate high-frequency switching current oscillation capture module: install a high-frequency oscillation circuit sensor on the gate loop of the SiC MOSFET to capture the high-frequency switching circuit oscillation i g-sw in an online non-contact manner, as shown in Figure 2 . The high-frequency oscillation circuit sensor adopts a hollow coil structure with a bandwidth of 1MHz-30MHz.

[0044] (2) Oscillation amplitude feature extraction module: the function of this module is to extract the amplitude feature information i g-peak that can be used for SiC MOSFET state monitoring from the gate opening high-frequency oscillation signal i g-sw . Since the oscillation frequency of i g-sw is high, this module adopts a digital-analog hybrid circuit composed of a high-frequency peak detection analog circuit and a signal sampling digital circuit.

[0045] (3) Running condition compensation module: during the running of the SiC MOSFET, the changes of the running conditions including the direct current voltage V d , the current i d and the temperature T j will affect the accuracy of the online monitoring of the device health state. This module online obtains the running parameters of the SiC MOSFET and compensates their influence on the online monitoring of the device health state.

[0046] (4) Aging state evaluation module: the function of this module is to compare the processed SiC MOSFET state detection parameters collected in different time periods to determine whether aging occurs and evaluate the degree of aging.

[0047] The system operation method of the present application is as shown in Figure 3 .

[0048] The SiC MOSFET gate oxide aging state monitoring is taken as an example to illustrate the feasibility and effectiveness of the present application.

[0049] (1) Experimental system

[0050] The experimental system is a SiC MOSFET bidirectional half-bridge converter as shown in Figure 4 , and the basic parameters are as shown in Table 1. The gate high-frequency switching current sensor and the high-frequency peak detection analog circuit are as shown in Figure 5 . The gate high-frequency switching current sensor is installed on the SiC MOSFET gate pin, which can capture the gate current opening oscillation signal online. The signal is extracted by the peak detection circuit to output to the host computer, and finally the gate oxide state analysis and evaluation are carried out by comparing the characteristic parameters extracted under different aging states. In the experiment, high gate bias voltage is applied to the measured SiC MOSFET gate and source to simulate the gate aging.

[0051] Table 1 Basic parameters of experimental system

[0052]

[0053] (2) Experimental results

[0054] The time-domain diagram of the opening gate current oscillation i g-sw under different gate oxide aging times at the operating point of the SiC MOSFET V d = 600 V, i d = 8 A, T j = 25℃ is as shown in Figure 6 . It can be seen that the peak value of the gate opening oscillation current monotonically decreases with the deepening of the aging degree, and the decline reaches 24.8%.

[0055] The collected gate current high-frequency oscillation is processed subsequently, and the peak value of the gate opening current oscillation is taken as the state monitoring parameter. The peak value detection holding circuit is used to extract the parameter, and the output can be approximately a straight line, which can collect the peak signal and reduce the requirement of the sampling frequency of the system. The output signal of the peak detection circuit in the operation of the SiC MOSFET converter is as shown in Figure 7 .

[0056] The influence of the deepening of the gate oxide aging on the change of the peak value of the gate opening current oscillation is as shown in Figure 8 , and it can be seen that i g-swThe peak value has obvious stratification phenomenon, and decreases with the gate oxide aging, which verifies the basic principle and feasibility of the online monitoring system. In order to further compensate the influence of the running condition on the gate oxide deterioration state monitoring, the running parameters need to be appropriately compensated. The SiC MOSFET running characteristic calibration experiment shows that the gate high-frequency switching oscillation current is basically independent of i d , and is approximately proportional to V d and T j . Accordingly, the gate high-frequency switching oscillation circuit peak value can be converted to the rated condition according to V d and T j to evaluate the aging state.

[0057] The present application measures the high-frequency switching oscillation current from the SiC MOSFET gate circuit online in a non-contact manner, and realizes safe and sensitive online monitoring of the early deterioration state of the device according to the change.

[0058] Embodiment 2

[0059] Referring to Figure 3 , the present embodiment provides an online state monitoring method for the SiC MOSFET online state monitoring system in embodiment 1, comprising the following steps:

[0060] Step S1, initialization: before starting the monitoring program, the preparation work is done, specifically including recording the time and the running parameters of the SiC MOSFET at the current time;

[0061] Step S2, switching current oscillation signal capture: the switching current oscillation signal is measured and captured from the SiC MOSFET gate circuit online through a non-contact high-frequency switching current oscillation sensor.

[0062] Step S3, amplitude feature extraction: the amplitude information that can be used for SiC MOSFET state monitoring is extracted from the gate current oscillation signal obtained from the above method.

[0063] Step S4, running condition compensation: according to the running characteristic of the SiC MOSFET gate high-frequency switching oscillation circuit peak value i g-peak =f(Vd,i d ,T j ), the gate high-frequency switching oscillation circuit peak value i g-peak extracted under the actual running condition is converted to the gate high-frequency switching oscillation circuit peak value i g-peak_com under the rated condition, so as to realize the condition compensation.

[0064] Step S5, aging state evaluation: according to the gate high-frequency switching oscillation circuit peak value i g-peak_comThe parameters are used to evaluate the aging state of the SiC MOSFET. When i g-peak When the trend changes over time, it can be determined that the device is aging, and the state of the device aging can be quantitatively evaluated according to the proportion of the change.

[0065] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of various equivalent modifications or replacements within the technical range disclosed by the present application, and these modifications or replacements should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A SiC MOSFET on-line condition monitoring method, characterized by, Comprising the following steps: Collecting the switching current oscillation signal of the SiC MOSFET gate loop in a non-contact manner, and extracting the amplitude information for state monitoring; Obtaining the operating parameter information of the SiC MOSFET, compensating the amplitude information based on the pre-calibrated operating characteristics of the SiC MOSFET gate high-frequency switching oscillation circuit peak value, and obtaining the compensated gate high-frequency switching oscillation circuit peak value under the rated operating condition. Based on the gate high-frequency switching oscillation circuit peak value under the rated operating condition, the degree of device aging is evaluated.

2. The SiC MOSFET on-line condition monitoring method according to claim 1, characterized in that, Based on the switching current oscillation signal, the amplitude information for state monitoring is obtained through high-frequency peak value detection and signal sampling.

3. The method of claim 1, wherein the SiC MOSFET is a SiC MOSFET of a power inverter. The operating parameter information includes at least one of DC voltage, current, and temperature.

4. The method of claim 1, wherein, The evaluation of the degree of device aging is specifically: By comparing the gate high-frequency switching oscillation circuit peak value obtained this time and the historical measurement gate high-frequency switching oscillation circuit peak value, the degree of device aging is quantitatively evaluated.

5. The method of claim 1, wherein, The switching current oscillation signal is collected from the SiC MOSFET gate loop by a non-contact high-frequency switching current oscillation sensor.

6. The method of claim 5, wherein the SiC MOSFET is a SiC MOSFET of a power converter. The bandwidth of the high-frequency switching current oscillation sensor is 1MHz-30MHz.

7. A SiC MOSFET on-line condition monitoring system characterized by, Comprising: A gate high-frequency switching current oscillation capture module, comprising a high-frequency oscillation circuit sensor arranged in the SiC MOSFET gate loop, for capturing the switching current oscillation signal in a non-contact manner online; An oscillation amplitude feature extraction module for extracting the amplitude information for SiC MOSFET state monitoring based on the switching current oscillation signal; An operating condition compensation module for collecting operating parameter information, compensating the amplitude information based on the pre-calibrated operating characteristics of the SiC MOSFET gate high-frequency switching oscillation circuit peak value, and obtaining the compensated gate high-frequency switching oscillation circuit peak value under the rated operating condition. An aging state evaluation module for quantitatively evaluating the degree of device aging based on the gate high-frequency switching oscillation circuit peak value under the rated operating condition.

8. The on-line SiC MOSFET condition monitoring system of claim 7, wherein, The oscillation amplitude feature extraction module includes a high-frequency peak value detection analog circuit and a signal sampling digital circuit.

9. An electronic device, comprising: Comprising: One or more processors and a memory, the memory storing one or more programs, the one or more programs including instructions for executing the SiC MOSFET online state monitoring method according to any one of claims 1-6.

10. A computer-readable storage medium, characterized in that, Comprising one or more programs for one or more processors of an electronic device to execute, the one or more programs including instructions for executing the SiC MOSFET online state monitoring method according to any one of claims 1-6.

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