Automatic test device for bipolar degradation test of SiC MOSEFET body diode
By designing an automated testing device for bipolar degradation testing of SiC MOSFET body diodes, the problems of temperature control and characteristic evaluation of SiC MOSFET body diodes during testing were solved, and the safety and degradation degree of the devices were evaluated.
Patent Information
- Application Number
- CN202422891293.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-26
- Publication Date
- 2025-12-02
- Estimated Expiration
- 2034-11-26
AI Technical Summary
Existing technologies struggle to stably control device temperature during bipolar degradation tests of SiC MOSFET body diodes, leading to device failure, and lack effective methods for evaluating dynamic and static characteristics.
An automated testing device for bipolar degradation testing of SiC MOSFET body diodes was designed, including a control unit, a human-machine interface module, a drain-source voltage sampling circuit, a temperature measurement circuit, an electronic switch, a current source, a logic control unit, a pulse generation circuit, a programmable voltage source, a cooling device, a dynamic characteristic evaluation circuit, and a data processing unit, to realize temperature control and characteristic evaluation during automated testing.
It enables stable control of device temperature during SiC MOSFET bipolar degradation testing, ensuring device safety, and allows for dynamic and static characteristic evaluation to assess the degree of degradation.
Smart Images
Figure CN223624368U_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of SiC power semiconductor device technology, and more specifically, relates to an automated test device for bipolar degradation testing of SiC MOSEFET body diodes. Background Technology
[0002] Wide-bandgap semiconductor devices, represented by silicon carbide (SiC) MOSFETs, offer advantages such as smaller chip area, lower on-resistance, and higher operating frequencies, enabling power electronic converters to continuously evolve towards higher frequencies, higher power densities, and smaller sizes. SiC MOSFETs contain a body diode formed by a PN junction. This body diode exhibits short reverse recovery time and low recovery loss, resulting in excellent forward operating characteristics.
[0003] However, when a SiC MOSFET is forward-biased, the on-state voltage of the body diode increases over time as a continuous current flows through it, a phenomenon known as bipolar degradation. This is primarily caused by dislocation defects on the basal plane of the SiC MOSFET substrate. When the body diode is turned on, the energy released by the recombination of electrons and holes causes stacking faults to propagate at these dislocations. After bipolar degradation occurs, the on-state resistance of the SiC MOSFET increases, leading to increased losses during operation. Therefore, it is necessary to evaluate body diode degradation. Currently, DC mode testing is commonly used, where a DC current is applied to the body diode, keeping it continuously operational. The larger the current, the more likely it is to trigger stacking fault growth at the dislocations, resulting in bipolar degradation.
[0004] However, applying a large current to the body diode causes a rapid rise in device temperature, potentially leading to device failure. Furthermore, to prevent the SiC MOSFET from forward-biased conduction, a reverse voltage needs to be applied between its gate and source. Therefore, it is necessary to design automated testing equipment and ensure stable temperature control of the device during body diode degradation testing. Additionally, after the device completes the corresponding degradation test, separate dynamic and static tests are required to evaluate the degree of degradation and the test results. Utility Model Content
[0005] To address the shortcomings of existing technologies, the purpose of this application is to provide an automated testing device for bipolar degradation testing of SiC MOSFET body diodes. This device enables automated testing of SiC MOSFET bipolar degradation, stabilizes the device temperature during the automated testing process, and evaluates the degree of device degradation (including dynamic and static characteristics) after the test.
[0006] This application relates to an automated testing device for bipolar degradation testing of SiC MOSEFET body diodes. The automated testing device includes: a control unit, a human-machine interface module, a drain-source voltage sampling circuit, a temperature measurement circuit, an electronic switch, a current source, a logic control unit, a pulse generation circuit, a programmable voltage source, a cooling device, a dynamic characteristic evaluation circuit, and a data processing unit; wherein...
[0007] The first input terminal of the control unit is connected to the output terminal of the human-computer interaction module, and the input terminal of the human-computer interaction module is connected to the data processing unit;
[0008] The second input terminal of the control unit is connected to the output terminal of the drain-source voltage sampling circuit. The positive input terminal of the drain-source voltage sampling circuit is connected to the drain of the device under test, and the negative input terminal is connected to the source of the device under test.
[0009] The third input terminal of the control unit is connected to the output terminal of the temperature measurement circuit, which is in close contact with the surface of the device under test.
[0010] The first output terminal of the control unit is connected to the control terminal of the electronic switch. The electronic switch is electrically connected to the current source. The positive terminal of the current source is connected to the source of the device under test, and the negative terminal is connected to the drain of the device under test.
[0011] The second output terminal of the control unit is connected to the logic control unit, the output terminal of the logic control unit is connected to the control terminal of the pulse generation circuit, the output terminal of the pulse generation circuit is connected to the control terminal of the programmable voltage source, the positive terminal of the programmable voltage source is connected to the gate of the device under test, and the negative terminal is connected to the source of the device under test.
[0012] The third output terminal of the control unit is connected to the control terminal of the cooling device, which is placed close to the device under test.
[0013] The switching transistor in the dynamic characteristic evaluation circuit is the device under test, and its output is connected to the human-machine interaction module through the data processing unit.
[0014] In one illustrated embodiment, the control unit is an MCU, an FPGA chip, or a SoC.
[0015] In one illustrated embodiment, the human-machine interface module is configured to receive settings for the maximum temperature, forward current, and conduction duration during a bipolar degradation test, display temperature data and drain-source voltage during the bipolar degradation test, and / or display the switching dynamic characteristic curve of the device under test.
[0016] In one illustrated embodiment, the temperature measurement circuit is a temperature sensor.
[0017] In one illustrated embodiment, the electronic switch is a relay, the coil of which is connected to a control unit to be energized or de-energized according to the control unit's command; the contacts of the relay are connected in series in a current source circuit.
[0018] In one illustrated embodiment, the logic control unit is an FPGA or a CPLD.
[0019] In one illustrated embodiment, the pulse generating circuit continuously outputs a low-level pulse signal during the bipolar degradation test of the body diode; after the bipolar degradation test of the body diode ends, it outputs two high-level pulses with different pulse widths.
[0020] In one illustrated embodiment, the load inductor in the dynamic characteristic evaluation circuit is an air-core inductor.
[0021] In one illustrated embodiment, the cooling device is either an air-cooled heat dissipation device or a water-cooled heat dissipation device.
[0022] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art:
[0023] This application provides an automated testing device for bipolar degradation testing of SiC MOSFET body diodes. A control unit generates the control logic required for the SiC MOSFET bipolar degradation test, driving electronic switches and the logic control unit to complete the automated testing process. Simultaneously, a temperature measurement circuit measures the temperature of the device under test (DUT) and sends the real-time temperature readings to the control unit. This prompts the control unit to generate a control signal to activate a cooling device. Under the control signal, the cooling device cools the SiC MOSFET under test when the measured temperature exceeds the device's maximum allowable temperature, thus stabilizing the device temperature during the automated SiC MOSFET bipolar degradation test. Furthermore, after the SiC MOSFET bipolar degradation test, a dynamic characteristic evaluation circuit can be connected to a data processing unit and then to a human-machine interface module to perform dynamic characteristic testing of the SiC MOSFET under test. Additionally, a drain-source voltage sampling circuit and a control unit can be used to perform static characteristic testing of the SiC MOSFET under test, thereby assessing its degradation state. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the structure of an automated testing device for bipolar degradation testing of SiC MOSEFET body diodes provided in this application.
[0025] Figure 2 This is a schematic diagram of the drain-source voltage sampling circuit structure provided in the embodiment of this application.
[0026] Figure 3 This is a schematic diagram of the dynamic characteristic evaluation circuit structure provided in the embodiments of this application. Detailed Implementation
[0027] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.
[0028] In this article, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The symbol " / " in this article indicates that the related objects are in an "or" relationship; for example, A / B means A or B.
[0029] The terms "first" and "second," etc., used in the specification and claims herein are used to distinguish different objects, not to describe a specific order of objects. For example, "first response message" and "second response message," etc., are used to distinguish different response messages, not to describe a specific order of response messages.
[0030] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.
[0031] In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more, for example, multiple processing units means two or more processing units, multiple elements means two or more elements, etc.
[0032] The embodiments of this application are described below with reference to the accompanying drawings.
[0033] like Figure 1As shown, this application provides an automated testing device for bipolar degradation testing of SiC MOSEFET body diodes. The automated testing device includes: a control unit, a human-machine interface module, a drain-source voltage sampling circuit, a temperature measurement circuit, an electronic switch, a current source, a logic control unit, a pulse generation circuit, a programmable voltage source, a cooling device, a dynamic characteristic evaluation circuit, and a data processing unit. The first input terminal of the control unit is connected to the output terminal of the human-machine interface module, and the input terminal of the human-machine interface module is connected to the data processing unit. The second input terminal of the control unit is connected to the output terminal of the drain-source voltage sampling circuit, with the positive input terminal of the drain-source voltage sampling circuit connected to the drain of the device under test and the negative input terminal connected to the source of the device under test. The third input terminal of the control unit is connected to the output terminal of the temperature measurement circuit. The measurement circuit is placed in close contact with the surface of the device under test (DUT). The first output terminal of the control unit is connected to the control terminal of an electronic switch, which is electrically connected to a current source. The positive terminal of the current source is connected to the source of the DUT, and the negative terminal is connected to the drain of the DUT. The second output terminal of the control unit is connected to a logic control unit, the output terminal of which is connected to the control terminal of a pulse generation circuit. The output terminal of the pulse generation circuit is connected to the control terminal of a programmable voltage source, the positive terminal of which is connected to the gate of the DUT, and the negative terminal is connected to the source of the DUT. The third output terminal of the control unit is connected to the control terminal of a cooling device, which is placed close to the DUT. The switching transistor in the dynamic characteristic evaluation circuit is the DUT, and its output terminal is connected to the human-machine interface module via a data processing unit.
[0034] The control unit is configured to receive settings for the maximum temperature, forward current, and conduction duration in a bipolar degradation test via a human-machine interface module; acquire real-time measured temperature and drain-source voltage; control the closing / closing of electronic switches; control the logic control unit to perform bipolar degradation tests / dual-pulse detection; and control the start / stop of the cooling device. In one illustrated embodiment, the control unit is an MCU, an FPGA chip, or a SoC.
[0035] The human-machine interface module is configured to receive settings for the maximum temperature, forward current, and conduction time during the bipolar degradation test, display temperature data and drain-source voltage during the bipolar degradation test, and / or display the switching dynamic characteristic curve of the device under test.
[0036] The drain-source voltage sampling circuit is configured to measure the drain-source voltage of the SiC MOSEFET in real time. In one illustrated embodiment, as... Figure 2As shown, when the SiC MOSFET is turned on, a current source injects a certain current into the SiC MOSFET through resistor R1 and high-voltage diode D1. By sampling the voltage across capacitor C1, which consists of the voltage drop across resistor R1, the voltage drop across high-voltage diode D1, and the drain-source voltage drop of the device, the drain-source voltage drop can be calculated.
[0037] The temperature measurement circuit is configured to measure the temperature of the SiC MOSEFET in real time. Under DC current, the device heats up, causing its temperature to rise. After a period of time, thermal equilibrium is reached, and the internal and external temperatures can be considered to be the same. In one illustrated embodiment, the temperature measurement circuit is a temperature sensor attached directly to the surface of the SiC MOSEFET heatsink. The temperature sensor includes, but is not limited to, a PT100 thin-film resistance temperature sensor.
[0038] The electronic switch is configured to control the current source to operate normally or disconnect. In one illustrated embodiment, the electronic switch is a relay, the coil of which is connected to a control unit to be energized or de-energized according to the control unit's control; the relay contacts are connected in series in the current source circuit.
[0039] The current source is configured to provide a constant current to cause the body diode to degrade.
[0040] During the bulk diode degradation experiment, the pulse generation module continuously outputs a low-level pulse signal, thereby controlling the voltage source to output a -5V voltage. At this time, the gate and source of the device under test are off. After the experiment, the pulse generation module outputs two high-level pulses (+15V) with different pulse widths to control the gate of the SiC MOSFET to turn on and off, thus testing the device's dynamic performance. The duty cycle is related to the load current in the dynamic characteristic evaluation circuit.
[0041] The programmable voltage source is configured to provide a stable negative voltage to the gate-source junction during the body diode degradation experiment, thereby completely closing the device channel and ensuring that all current flows through the body diode, causing it to undergo bipolar degradation. In one illustrated embodiment, the negative voltage is -5V.
[0042] The cooling device is configured for SiC MOSEFET cooling. In one illustrated embodiment, the cooling device is either an air-cooled device or a water-cooled device.
[0043] Dynamic characteristic evaluation circuit internals and its external interfaces, such as Figure 3 As shown, the dynamic characteristic evaluation circuit is a half-bridge structure, consisting of the upper bridge arm (Q... H ) and lower bridge arm (Q L The air-core inductor is selected as the load inductor L in the circuit and its driving circuit.load Support capacitor C bank Composition, external DC voltage source V dc .
[0044] The device under test is located in the lower bridge arm. When the device under test is turned on, the current across the device flows through the load inductor. When the required current for measurement is reached, the device is turned off, and the switching dynamic characteristics of the device at that current level can be obtained.
[0045]
[0046] in, This is the high-level time.
[0047] In one illustrated embodiment, the data processing unit is an oscilloscope.
[0048] The automated testing device operates as follows: First, it receives settings for the maximum temperature, forward current, and conduction time in the bipolar degradation test via a human-machine interface module. Second, the control unit controls the logic control module and pulse generation circuit to perform the bipolar degradation test. The programmable voltage source outputs a negative voltage to the gate-source junction, turning off the SiC MOSFET gate and placing the device in a forward-off state. Third, the control unit controls the electronic switch to close, and the current source applies a forward current to the source-drain junction. Simultaneously, the temperature measurement circuit measures the temperature of the device under test in real time and controls the device temperature through a cooling device to ensure it does not exceed the maximum allowable temperature. Then, when the conduction time reaches the set conduction duration, the control unit controls the electronic switch to turn off the DC current source. Finally, the temperature measurement circuit continues to monitor the device temperature until it cools to room temperature, at which point the control unit turns off the programmable power supply, ending the automated test. After the experiment, the control unit controls the logic control module and pulse generation circuit to perform dynamic performance testing. The pulse generation module outputs two high-level pulses (+15V) with different pulse widths to control the gate of the SiC MOSFET to turn on and off, thus testing the device's dynamic performance. The switching transistor in the dynamic characteristic evaluation circuit turns off when it reaches the required measurement current, obtaining the device's switching dynamic characteristics at that current level. Simultaneously, the controller samples the drain-source voltage of the SiC MOSFET through a drain-source voltage sampling circuit to obtain the device's static characteristics.
[0049] This application follows the principles for determining the magnitude of the forward current applied to the body diode:
[0050] (1) Ensure that the temperature of the device does not exceed the maximum rated value during the test;
[0051] (2) Place the device in a high-temperature chamber and adjust the temperature of the chamber to the maximum rated value of the device, and measure the forward voltage of the body diode of the device;
[0052] (3) Install the device on the test bench, continuously increase the current applied to the body diode of the device by stepping, and measure the forward voltage of the body diode. When the measured forward voltage reaches the measured value of the device in the high temperature chamber, take the current applied at this time as the current applied during the test.
[0053] To assess the degradation level of the body diode, the degradation level assessment module in the control unit is activated. This module is configured to acquire the drain-source voltage of the SiC MOSFET at different conduction durations, compare the measured voltages with those of healthy devices, quantify the degradation level of the device, and output the assessment result. The degradation level quantification algorithm is existing technology. The different conduction durations can be combinations of 30h, 50h, 70h, and 100h.
[0054] It should be understood that expressions such as “comprising” and “may include” used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as “comprising” and / or “having” are to be interpreted as indicating a particular characteristic, number, operation, constituent element, component, or combination thereof, but not to exclude the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.
[0055] Furthermore, in this application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.
[0056] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. The directional terms mentioned in the embodiments of this application, such as "top," "bottom," "inner," "outer," "left," and "right," are only for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of this application, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.
[0057] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. An automated testing device for bipolar degradation testing of SiC MOSEFET bulk diodes, characterized in that, include: The system includes a control unit, a human-machine interface module, a drain-source voltage sampling circuit, a temperature measurement circuit, an electronic switch, a current source, a logic control unit, a pulse generation circuit, a programmable voltage source, a cooling device, a dynamic characteristic evaluation circuit, and a data processing unit; among which, The first input terminal of the control unit is connected to the output terminal of the human-computer interaction module, and the input terminal of the human-computer interaction module is connected to the data processing unit; The second input terminal of the control unit is connected to the output terminal of the drain-source voltage sampling circuit. The positive input terminal of the drain-source voltage sampling circuit is connected to the drain of the device under test, and the negative input terminal is connected to the source of the device under test. The third input terminal of the control unit is connected to the output terminal of the temperature measurement circuit, which is in close contact with the surface of the device under test. The first output terminal of the control unit is connected to the control terminal of the electronic switch. The electronic switch is electrically connected to the current source. The positive terminal of the current source is connected to the source of the device under test, and the negative terminal is connected to the drain of the device under test. The second output terminal of the control unit is connected to the logic control unit, the output terminal of the logic control unit is connected to the control terminal of the pulse generation circuit, the output terminal of the pulse generation circuit is connected to the control terminal of the programmable voltage source, the positive terminal of the programmable voltage source is connected to the gate of the device under test, and the negative terminal is connected to the source of the device under test. The third output terminal of the control unit is connected to the control terminal of the cooling device, which is placed close to the device under test. The switching transistor in the dynamic characteristic evaluation circuit is the device under test, and its output is connected to the human-machine interaction module through the data processing unit.
2. The automated testing device as described in claim 1, characterized in that, The control unit is an MCU, FPGA chip, or SoC.
3. The automated testing device as described in claim 1, characterized in that, The human-machine interface module is configured to receive settings for the maximum temperature, forward current, and conduction time during the bipolar degradation test, display temperature data and drain-source voltage during the bipolar degradation test, and / or display the switching dynamic characteristic curve of the device under test.
4. The automated testing device as described in claim 1, characterized in that, The temperature measurement circuit is a temperature sensor.
5. The automated testing device as described in claim 1, characterized in that, The electronic switch is a relay, and the coil of the relay is connected to the control unit to be energized or de-energized according to the control of the control unit; the contacts of the relay are connected in series in the current source circuit.
6. The automated testing device as described in claim 1, characterized in that, The logic control unit is an FPGA or a CPLD.
7. The automated testing device as described in claim 1, characterized in that, The pulse generation circuit continuously outputs a low-level pulse signal during the bipolar degradation test of the body diode; after the bipolar degradation test of the body diode ends, it outputs two high-level pulses with different pulse widths.
8. The automated testing device as described in claim 1, characterized in that, The load inductor in the dynamic characteristic evaluation circuit is an air-core inductor.
9. The automated testing device as described in claim 1, characterized in that, The cooling device is either an air-cooled or a water-cooled device.