Automatic test apparatus and method for power mosfet performance evaluation

Abstract

The application relates to an automatic testing device and method for power MOSFET performance evaluation, and belongs to the technical field of power electronic power device testing. The automatic testing device comprises an upper computer, a power module, a controller module, a driving module, a load module and a detection module. Based on the device, MOSFET opening voltage testing, gate-source limit voltage testing, thermal resistance testing, short circuit testing, opening and closing waveform testing can be realized, and related working parameters of the MOSFET can be calculated according to the testing data, the performance of the MOSFET is comprehensively evaluated in actual application, the device architecture has high feasibility, the testing condition is easy to change, the device is easy to replace, and the testing efficiency is high; in addition, the device is convenient to use in data acquisition, has high application value, and is of great significance for guiding the selection of power MOSFET.

Description

Technical Field

[0001] The present invention belongs to the technical field of power electronic power device testing, and relates to an automatic testing device and method for power MOSFET performance evaluation. Background Art

[0002] Metal-oxide semiconductor field-effect transistors (MOSFETs) have the advantages of fast switching speed, high input impedance, easy driving, and no secondary breakdown phenomenon. They are widely used in analog and digital circuits. As the core component of modern power electronic systems, their performance parameters directly affect the efficiency, reliability and safety of the system. At present, the performance testing of power MOSFETs in the industry mainly relies on the data in the specifications provided by the manufacturer. However, these data are usually obtained in an idealized, static laboratory environment (such as constant temperature, fixed load, etc.), which makes it difficult to truly reflect the performance of the device under actual complex working conditions (such as wide temperature range, dynamic load changes, high-frequency switching stress, etc.). Existing testing technologies and equipment have the following limitations:

[0003] 1. Single and fragmented test parameters: Existing test methods often focus on a single performance indicator (such as on-resistance, threshold voltage, or switching time) and lack a comprehensive assessment of the synergistic effects of multiple parameters. For example, thermal resistance testing is often independent of electrical performance testing, making it impossible to quantify the impact of temperature rise on device dynamic characteristics. In addition, key parameters such as short-circuit withstand capability (SOA) and gate oxide limit voltage often rely on discrete equipment. The test process is lengthy and data integration is difficult, making it difficult to fully reflect the failure boundaries of the device in actual applications.

[0004] 2. Insufficient environmental adaptability: Existing test systems limit their control of temperature conditions to room temperature and lack the ability to automate testing over a wide temperature range. Power MOSFETs are often exposed to extreme temperatures in automotive and industrial applications, and their parameters, such as threshold voltage and on-resistance, drift significantly with temperature. Existing test methods are unable to dynamically simulate the impact of temperature changes on device performance, resulting in significant discrepancies between datasheets and actual application scenarios.

[0005] 3. Low test efficiency and automation: Traditional test equipment relies on manual operation to switch loads and adjust test conditions, and the process of replacing the device under test (DUT) is cumbersome. For example, thermal resistance testing requires long-term steady-state temperature rise monitoring, but existing solutions often rely on manual data recording, which is time-consuming and prone to human error. Furthermore, the measurement of dynamic parameters (such as switching loss) requires offline analysis using an oscilloscope, lacking real-time data processing and automated feedback mechanisms, making it difficult to meet the needs of batch testing.

[0006] 4. Limited dynamic load simulation capabilities: Existing simulated loads mostly use fixed resistors or simple electronic loads, which cannot accurately simulate transient loads in real applications (such as motor start-stop and short-circuit faults). In particular, in short-circuit testing, existing equipment has difficulty capturing the peak characteristics of drain-source voltage and current within microsecond timescales, resulting in insufficient SOA area assessment accuracy and inability to effectively predict device failure risks under fault conditions.

[0007] 5. Insufficient system integration and scalability: Most test platforms are composed of discrete power supplies, controllers, and data acquisition units. Communication protocols among these modules are inconsistent, resulting in poor system compatibility. For example, the lack of a CAN bus or high-speed digital interface leads to delays in test command and data transmission, making it difficult to achieve simultaneous multi-parameter acquisition and closed-loop control. Furthermore, existing architectures struggle to adapt to MOSFETs of varying package types. Component replacements require redesigning fixtures and wiring, reducing testing flexibility.

[0008] In summary, current MOSFET performance testing technology is relatively incomplete, testing only a specific MOSFET performance parameter. The test environment is often complex, making it impossible to fully evaluate the electrical performance parameters of MOSFET devices in actual application scenarios. This in turn affects their reliability and stability under different operating conditions, reducing system performance and safety. Therefore, considering MOSFET performance parameters such as turn-on voltage, limit voltage, short-circuit characteristics, heat dissipation capacity, and SOA area at different operating ambient temperatures, and exploring a comprehensive and easy-to-implement MOSFET automatic testing device and method built based on actual application scenarios, to comprehensively evaluate MOSFET performance is of great significance for selecting MOSFETs that are suitable for application scenario circuit requirements. Summary of the Invention

[0009] In view of this, the purpose of the present invention is to provide an automatic testing device and method for power MOSFET performance evaluation, which comprehensively evaluates the performance parameters of MOSFET such as turn-on voltage, limit voltage, short-circuit characteristics, heat dissipation capability, SOA area, etc. in actual application scenarios.

[0010] To achieve the above objectives, the present invention provides an automatic testing device for power MOSFET performance evaluation, which includes a host computer, a power module, a controller module, a drive module, a load module and a detection module.

[0011] The host computer is connected to the controller module via the CAN bus, receives the test data transmitted by the controller module, and calculates, organizes, and stores the test data; the host computer sends control instructions to the power module via the CAN bus. The controller module sends control instructions to the detection module, the drive module, and the load module respectively. The load module selects different loads according to the control instructions of the controller module to simulate different load conditions. The drive module includes a MOSFET to be tested and an H-bridge unit composed of the MOSFET to be tested, and drives the simulated load according to the control instructions sent by the controller module to test the MOSFET to be tested. The detection module collects the test data of the drive module according to the control instructions of the controller module and transmits it to the controller module.

[0012] Furthermore, the detection module includes a signal acquisition unit, a waveform detection unit, and a thermal testing unit. The signal acquisition unit is used to monitor and collect the real-time gate-source voltage, drain-source voltage, and drain-source current of the MOSFET under test; the waveform detection unit is used to monitor and collect the input and output voltage waveforms and input and output current waveforms of the H-bridge; and the thermal testing unit is used to monitor the surface temperature of the MOSFET under test.

[0013] Furthermore, the power supply module includes a first power supply and a second power supply. The first power supply supplies power to the controller module and the load module respectively; the second power supply provides a gate-source voltage to the MOSFET to be tested in the driver module according to control instructions from the host computer.

[0014] Furthermore, the load module includes a relay switch, a plurality of drive motors and a plurality of power resistors, and the controller module controls the relay switch to select different loads to be connected to the drive module.

[0015] Furthermore, the power module, controller module, drive module, load module and detection module are all placed in a temperature test box.

[0016] In another aspect, the present invention provides a testing method for evaluating the performance of a power MOSFET based on the above-mentioned device, the method comprising:

[0017] Test MOSFET gate-source turn-on voltage threshold: Determine the leakage current I at the gate-source turn-on voltage threshold D , set the temperature test box to the specified temperature, select the power resistor in the load module to connect to the MOSFET, the host computer controls the second power supply to supply power to the MOSFET gate, and gradually increases the gate voltage from 0V in a step-by-step manner according to the specified voltage step until the MOSFET drain-source voltage and current no longer change; the host computer sets I D Compare with the leakage current test value I0 to obtain the gate-source turn-on voltage threshold;

[0018] Test MOSFET gate-source limit voltage: determine the leakage current test value I0 and the test time T for each step of the gate-source limit voltage test. step1 , set the temperature test box to the specified temperature, select the power resistor in the load module and connect it to the MOSFET; the host computer controls the second power supply to supply power to the MOSFET gate, and controls the time for each step of the second power supply to output voltage to the gate to be T step1 , starting from the gate-source turn-on voltage threshold, the gate voltage is gradually increased in a step-by-step manner according to the specified voltage step until the gate oxide layer is damaged or the gate is turned off. D ≥I0; the host computer will I D Compare with I0 to obtain the gate-source limit voltage threshold;

[0019] Test the actual thermal resistance, actual maximum operating current and maximum stall current of MOSFET: Determine the thermal resistance value R from MOSFET junction to environment JA and the maximum withstand temperature T j , select the maximum simulated load of the load module and connect it to the H-bridge unit. The controller module outputs DC power to drive the H-bridge unit through the configured driver chip; collect the gate voltage, drain-source voltage, drain-source current, and the surface temperature of the upper and lower bridges of the H-bridge unit. The host computer calculates the actual thermal resistance, actual maximum operating current, and maximum locked-rotor current of the MOSFET based on the steady-state temperature rise, drain-source voltage, and drain-source current;

[0020] Test whether the MOSFET meets the SOA area limit range in the short-circuit state: Set the temperature test chamber to the specified temperature, select the load module's load motor and connect it to the H-bridge unit. The controller module outputs DC power to drive the H-bridge unit through the driver chip. During the driving process, the controller module sets a relay switch to short-circuit the source of the upper bridge MOSFET of the H-bridge unit to ground and short-circuit the drain of the lower bridge MOSFET of the H-bridge unit to power. The host computer determines whether the MOSFET meets the SOA area limit range in the short-circuit state based on the drain-source peak voltage, short-circuit peak current, and short-circuit duration during the short-circuit and short-circuit conditions.

[0021] Test MOSFET switching loss: Set the temperature test chamber to the specified temperature, select the load module's load motor and connect it to the H-bridge unit, set the controller module to drive current with different drive frequencies and duty cycles, and output the drive current to the load motor using PWM modulation. The controller module outputs the drive current to the gate of each MOSFET in the H-bridge unit from weakest to strongest through the configured driver chip; the host computer calculates the switching loss based on the drain-source voltage waveform and drain-source current waveform when the MOSFET is turned on and off under different gate drive currents, as well as the turn-on and turn-off times.

[0022] Furthermore, the host computer calculates the actual thermal resistance, actual maximum operating current and maximum locked-rotor current of the MOSFET based on the steady-state temperature rise, drain-source voltage and drain-source current, including:

[0023] The host computer calculates the actual thermal resistance R of the MOSFET based on the steady-state temperature rise ΔT1, drain-source voltage and drain-source current of the MOSFET. JA ;

[0024] The host computer calculates the actual thermal resistance R of MOSFET JA 、MOSFET maximum withstand temperature MaxT j , Maximum operating temperature T C And the drain-source on-resistance R DS(on) Calculate the actual maximum operating current I of the MOSFET DMAX ;

[0025] The host computer calculates the actual thermal resistance R of MOSFET JA , steady-state temperature rise ΔT2 during normal operation, MOSFET maximum withstand temperature MaxT j , Maximum operating temperature T C And the drain-source on-resistance R DS(on) Calculate the actual maximum locked-rotor current. The steady-state temperature rise ΔT2 during normal operation is obtained by the following method:

[0026] Select the load motor in the load module and connect it to the H-bridge unit. Set the controller module to drive the H-bridge with DC power. Use the thermal test unit to test the surface temperature of the upper and lower MOSFETs of the H-bridge respectively. Test for more than half an hour to test the temperature of the upper and lower MOSFETs of the H-bridge in steady state and obtain the steady-state temperature rise ΔT2 during normal operation.

[0027] Furthermore, for calculating the switching loss, it is specifically:

[0028] The host computer is based on the MOSFET opening time T r , drain-source voltage waveform and drain-source current waveform to calculate the turn-on loss of MOSFET; wherein, the turn-on time of MOSFET is T r is the drain-source voltage V DS Start to decrease to V DS Time that no longer changes;

[0029] The host computer determines the MOSFET's off time T f , drain-source voltage waveform, drain-source current waveform and switching frequency F SW Calculate the turn-off loss of MOSFET; wherein, the turn-off time of MOSFET is T f V DS Starts to increase to V DS Time that no longer changes.

[0030] The beneficial effects of the present invention are as follows: the present invention provides an automatic test device for power MOSFET performance evaluation. The device drive module can be set to test the MOSFET individually, or the MOSFET can be tested by forming an H-bridge. This device can perform MOSFET turn-on voltage testing, gate-source limit voltage testing, thermal resistance testing, short-circuit testing, turn-on and turn-off waveform testing, and other tests. In addition, the device detection module uses a combination of multiple load resistors and load motors to simulate a variety of different load scenarios, enriching the MOSFET testing environment. The automatic test device provided by the present invention can comprehensively evaluate the performance of MOSFETs based on actual application requirements. The device system architecture is highly feasible, test conditions are easy to change, components are easy to replace, the test efficiency is high, the data used for evaluation is convenient to obtain, the test device has high application value, and is of great significance for guiding the selection of power MOSFETs.

[0031] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0033] Figure 1 A schematic structural diagram of a MOSFET testing device provided in one embodiment of the present invention;

[0034] Figure 2 Schematic diagram of MOSFET turn-on / limit voltage test method;

[0035] Figure 3 is MOSFET V DS With V GS Schematic diagram of the changing trend of

[0036] Figure 4 This is a schematic diagram of the MOSFET Safe Operating Area;

[0037] Figure 5 This is a schematic diagram of the MOSFET short-circuit test method;

[0038] Figure 6 Turn on the waveform graph for MOSFET;

[0039] Figure 7This is the MOSFET turn-off waveform curve. DETAILED DESCRIPTION

[0040] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0041] Among them, the accompanying drawings are only for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting the present invention. In order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the dimensions of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings.

[0042] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc. indicating directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0043] In view of the problems that the existing MOSFET testing method does not consider the influence of the working environment temperature, the testing environment is complex, and the electrical performance parameters of the MOS device cannot be fully evaluated, an embodiment of the present invention provides an automatic testing device for power MOSFET performance evaluation. Figure 1 As shown, the device includes a host computer, a power module, a controller module, a drive module, a load module and a detection module.

[0044] Among them, the power supply module includes a first power supply and a second power supply. The first power supply is used to provide working voltage for the control module and the load module. The second power supply outputs a specified voltage signal according to the instructions of the host computer to provide the driving module with a voltage of the test application conditions.

[0045] The host computer exchanges data with the controller module through CAN communication and is responsible for sending control instructions to the second power supply; the controller module provides control signals to the drive module according to test requirements and controls the relay switch of the load module to select different loads to be connected to the drive module.

[0046] The driving module includes an H-bridge unit and a MOSFET unit, and is responsible for driving the analog load according to the control signal.

[0047] The load module includes a motor unit and a power resistor unit, and is used to simulate different load conditions.

[0048] The detection module includes a signal acquisition unit, a waveform detection unit, and a thermal testing unit. Based on instructions from the controller module, it detects the voltage, current, input / output waveforms of the driver module, and the surface temperature of the MOSFET. The sampled data is then transmitted to the controller, which then interacts with the host computer to calculate, organize, and store the final test data. The signal acquisition unit monitors the real-time gate-source voltage, drain-source voltage, and drain-source current signals of the MOSFET unit; the waveform detection module monitors the input / output voltage and current waveforms of the H-bridge unit in the driver module; and the thermal testing unit detects the surface temperature of the MOSFET in the H-bridge unit.

[0049] Based on the above test device, it is possible to perform performance tests such as thermal resistance, limit voltage, turn-on voltage, switching waveform, and short-circuit test of MOSFET, and evaluate the performance of MOSFET in different application scenarios.

[0050] The method for using the test device to test and evaluate the performance of MOSFET includes:

[0051] S1. First determine the leakage current I under the threshold voltage D In this embodiment, V GS(th) =2.4~3.4V, leakage current I D = 250μA, taking the 12V system on board as an example, then set the temperature test box to the specified temperature (normal temperature is 25℃ / low temperature is -40℃ / high temperature is 85℃) and stabilize for half an hour. Figure 2As shown, according to the driving current requirements of the actual application, the controller turns on the relay switch, selects the power resistor in the load module to be connected to the source of the MOSFET in the MOSFET unit of the driving module, in this embodiment, the actual application driving current is 2A, and the power resistor R1 = 5Ω / 100W is selected. The first power supply simulates the on-board 12V system to provide the drain voltage, the gate is connected to the ground in parallel with the pull-down resistor, the second power supply is connected to the gate, and the host computer controls the second voltage source to gradually increase the gate voltage from 0 in a 0.2V step manner until the drain-source voltage and current no longer change. The controller sends an instruction to the detection module, and the signal acquisition unit of the detection module detects the real-time gate voltage, drain-source voltage and drain-source current according to the controller instruction, and transmits them to the host computer through the controller. The host computer can display the sampled voltage and current data in real time, and I D Compare with the leakage current test value I0 to obtain and record the gate-source turn-on voltage threshold. Figure 3 Shown is the MOSFET drain-source voltage V DS With the gate-source voltage V GS The trend curve of the change of V under high temperature GS(th) is 3V, V at low temperature GS(th) is 3.6V.

[0052] S2. Determine the leakage current test value I0 of the gate-source limit voltage and the test time T of each step of the gate-source limit voltage test. step1 In this embodiment, V GS =-20~20V, leakage current I0=250μA, each step test time T step1 Set to 30 seconds. Taking the vehicle 12V system as an example, set the temperature test box to the specified temperature (normal temperature is 25℃ / low temperature is -40℃ / high temperature is 85℃) and stabilize for half an hour. Figure 2 As shown, the controller turns on the relay switch, selects the power resistor in the load module to be connected to the source of the MOSFET in the MOSFET unit of the driver module, in this embodiment, the driving current is 2A, the power resistor R1 is selected to be 5Ω / 100W, the first power supply simulates the on-board 12V system to provide the drain voltage, the gate is connected to the ground in parallel with the pull-down resistor, the second power supply is connected to the gate, and the host computer sets the time for the second power supply to output the gate voltage at each step to T step1 , then turn off the gate voltage source, gradually increase the gate voltage in 1V steps starting from the threshold voltage, then turn off the gate voltage source, and observe the gate oxide layer until the gate oxide layer shows signs of damage or the gate is turned off. D ≥I0, the controller sends an instruction to the detection module. The signal acquisition unit of the detection module detects the gate voltage, drain-source voltage and drain-source current after the gate voltage is turned off according to the controller instruction, and transmits them to the host computer through the controller. The host computer can display the sampled voltage and current data in real time, and the drain-source current I DCompare with I0 to obtain and record the gate-source limit voltage threshold. In this embodiment, the limit voltage V GS The limit voltage at low temperature is 58V. GS is 52V.

[0053] S3. Determine the thermal resistance R from the MOSFET junction to the environment JA and the maximum MOSFET withstand temperature T j According to the maximum current requirement of the actual application, the controller selects the maximum simulated load in the load module (the power resistor at both ends of the load motor is connected in parallel to make the H-bridge output current reach the maximum simulated load current) and connects it to the H-bridge unit of the driver module. In this embodiment, the maximum temperature that the MOSFET can withstand is T j =175℃, the maximum current is 10A, and the power resistor is R=1Ω / 200W; the controller module is configured with a driver chip, which outputs a DC drive H-bridge through the driver chip. The controller sends instructions to the detection module. The thermal test unit of the detection module tests the surface temperature of the upper and lower MOSFETs of the H-bridge driver tube according to the controller instructions. The test is carried out for more than half an hour. The signal acquisition unit detects the gate voltage, drain-source voltage and drain-source current in steady state, and transmits them to the host computer through the controller. The thermal test unit tests the surface temperature of the upper and lower MOSFETs of the H-bridge driver tube in steady state and transmits them to the host computer through the controller. In this embodiment, the initial value of the measured surface temperature of the MOSFET is T A1 =33.4℃, T A2 =32.9℃, steady-state drain-source voltage V DS1 =0.052V, V DS2 =0.05V, leakage current I D2 =I D1 =10.38A, the surface temperature of MOSFET is T J1 =58.6℃, T J2 =58.6°C. The host computer can calculate the actual thermal resistance, actual maximum operating current, and maximum locked-rotor current of the MOSFET based on the steady-state temperature rise, drain-source voltage, and current.

[0054] S4. Taking the 12V system on board as an example, set the temperature test box to the specified temperature (normal temperature is 25℃ / low temperature is -40℃ / high temperature is 85℃) and stabilize for half an hour. According to the current requirements of the actual application, the controller selects the load motor of the load module and connects it to the H-bridge unit of the drive module. In this embodiment, the drive current is 2A, and the power resistor is R = 5Ω / 200W. Figure 5As shown, the first power supply simulates the vehicle's 12V system to provide drain voltage, and the controller module outputs DC power to drive the H-bridge through the driver chip. During the driving process, the controller sets a relay switch to short the source of the upper tube of the H-bridge to ground / short the drain of the lower tube of the H-bridge to power. The controller sends a command to the detection module. The waveform detection unit of the detection module tests the drain-source peak voltage, short-circuit peak current waveform and short-circuit duration when shorting to power / short to ground, and determines whether the MOSFET meets the SOA area limit range when shorted. The SOA area mainly includes R DS(on) Limit, current I D There are five limit lines: limit, maximum power limit, thermal stability limit and BVDSS limit.

[0055] In this embodiment, the actual measured current peak value during short-circuit at room temperature is 60.934A, the shutdown time is 4.4μs, and V DS The peak value is 20.326V, the current peak value during short-circuit is 78.706A, the shutdown time is 7.2μs, and V DS The peak value is 20.801V. The SOA area is as follows Figure 4 As shown, the short-circuit peak current should meet I D Limit line, drain-source peak voltage V DS The BVDSS limit line should be met.

[0056] S5. Taking the on-board 12V system as an example, set the temperature test box to the specified temperature (normal temperature is 25℃ / low temperature is -40℃ / high temperature is 85℃) and stabilize for half an hour. According to the current requirements of the actual application, the load motor of the load module is selected by the controller to be connected to the H-bridge unit of the drive module. The controller module sets the driving current with different driving frequencies and duty cycles according to the application requirements. Here, the driving frequency is set to 20KHz and the duty cycle is 50%. The driving current is output to the load through the driver chip in the form of PWM modulation. The driver chip outputs the driving current to each MOSFET gate in the H-bridge unit, and the gate driving current is from the weakest to the strongest. Here, the driving current range is set to 0.5mA~64mA. The controller sends instructions to the detection module. The waveform detection unit of the detection module tests the gate-source voltage, drain-source voltage and current waveform and the start-up and shutdown time when the MOSFET is turned on and off under different gate drive currents, and transmits them to the host computer through the controller. The turn-on waveform and turn-off waveform under a certain drive current in this embodiment are as follows. Figure 6 、 Figure 7 shown.

[0057] The actual thermal resistance, actual maximum operating current, and actual maximum locked-rotor current of the MOSFET in step S3 are calculated by the following steps:

[0058] S301, the host computer obtains the data of the signal acquisition unit and the data of the thermal test module, and calculates the actual thermal resistance R of the MOSFET based on the steady-state temperature rise ΔT1, drain-source voltage and drain-source current of the MOSFET JA ;

[0059] S302, the host computer calculates the actual thermal resistance R of MOSFET JA 、MOSFET maximum withstand temperature MaxT j , Maximum operating temperature T C , and the drain-source on-resistance R DS(on) Calculate the actual maximum continuous operating current I of the MOSFET DMAX ;

[0060] S303, according to the current requirements of the actual application, the controller switches on the relay switch, selects the load motor in the load module and connects it to the H-bridge unit of the driver module, sets the DC drive H-bridge, and sends instructions to the detection module. The thermal test unit of the detection module tests the surface temperature of the upper and lower MOSFETs of the H-bridge driver tube respectively. The test is carried out for more than half an hour. The temperature of the upper and lower MOSFETs of the H-bridge driver tube in steady state is tested, and the steady-state temperature rise during normal operation is obtained and transmitted to the host computer. The host computer calculates the temperature rise based on the actual thermal resistance R JA , steady-state temperature rise ΔT2 during normal operation, MOSFET maximum withstand temperature MaxT j , Maximum operating temperature T C And the drain-source on-resistance R DS(on) Calculate the actual maximum locked-rotor current.

[0061] In step S5, the switching loss is calculated based on the gate-source voltage, drain-source voltage, current waveform, and turn-on and turn-off time of the MOSFET when it is turned on and off under different gate drive currents. Specifically, it is:

[0062] S501, the host computer obtains the drain-source voltage V when the MOSFET is turned on, which is collected by the waveform detection unit DS , gate-source voltage V GS and drain-source current I D Waveform data, based on the MOSFET turn-on time T r , drain-source voltage waveform and drain-source current waveform to calculate the MOSFET turn-on loss. r V DS Start to decrease to V DS Time that no longer changes.

[0063] S502, the host computer obtains the drain-source voltage V when the MOSFET is turned on, which is collected by the waveform detection unit DS , gate-source voltage V GSand the drain-source current waveform I D Data, based on the MOSFET turn-off time T f , drain-source voltage waveform, drain-source current waveform and switching frequency F in practical applications SW Calculate the turn-off loss of MOSFET. The turn-off time of MOSFET is T f V DS Starts to increase to V DS Time that no longer changes.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A test method for power MOSFET performance evaluation based on an automatic test device, the device comprising a host computer, a power module, a controller module, a driver module, a load module, and a detection module; The host computer is connected to the controller module via a CAN bus, receives the test data transmitted by the controller module, and calculates, organizes and stores the test data; the host computer sends control instructions to the power module via the CAN bus; the controller module sends control instructions to the detection module, the drive module and the load module respectively; the load module selects different loads according to the control instructions of the controller module to simulate different load conditions; the drive module includes a MOSFET to be tested and an H-bridge unit composed of the MOSFET to be tested, and drives the simulated load according to the control instructions sent by the controller module to test the MOSFET to be tested; the detection module collects the test data of the drive module according to the control instructions of the controller module and transmits it to the controller module; The detection module includes a signal acquisition unit, a waveform detection unit and a thermal test unit; the signal acquisition unit is used to monitor and collect the real-time gate-source voltage, drain-source voltage and drain-source current of the MOSFET to be tested; the waveform detection unit is used to monitor and collect the input and output voltage waveforms and input and output current waveforms of the H-bridge unit; The thermal testing unit is used to monitor the surface temperature of the MOSFET to be tested; The power supply module includes a first power supply and a second power supply; the first power supply supplies power to the controller module and the load module respectively; the second power supply provides a gate-source voltage to the MOSFET to be tested in the driver module according to the control instruction of the host computer; The load module includes a relay switch, multiple drive motors and multiple power resistors, and the controller module controls the relay switch to select different loads to connect to the drive module; The power module, controller module, drive module, load module and detection module are all placed in a temperature test box; Characterized in that the method comprises: Test MOSFET gate-source turn-on voltage threshold: Determine the leakage current I at the gate-source turn-on voltage threshold D , set the temperature test box to the specified temperature, select the power resistor in the load module to connect to the MOSFET, the host computer controls the second power supply to supply power to the MOSFET gate, and gradually increases the gate voltage from 0V in a step-by-step manner according to the specified voltage step until the MOSFET drain-source voltage and current no longer change; the host computer sets I D Compare with the leakage current test value I0 to obtain the gate-source turn-on voltage threshold; Test MOSFET gate-source limit voltage: determine the leakage current test value I0 and the test time T for each step of the gate-source limit voltage test. step1 , set the temperature test box to the specified temperature, select the power resistor in the load module and connect it to the MOSFET; the host computer controls the second power supply to supply power to the MOSFET gate, and controls the time for each step of the second power supply to output voltage to the gate to be T step1 , starting from the gate-source turn-on voltage threshold, the gate voltage is gradually increased in a step-by-step manner according to the specified voltage step until the gate oxide layer is damaged or the gate is turned off. D ≥I0; the host computer will I D Compare with I0 to obtain the gate-source limit voltage threshold; Test the actual thermal resistance, actual maximum operating current and maximum stall current of MOSFET: Determine the thermal resistance value R from MOSFET junction to environment JA and maximum temperature , select the maximum simulated load of the load module and connect it to the H-bridge unit. The controller module outputs DC power to drive the H-bridge unit through the configured driver chip; collect the gate voltage, drain-source voltage, drain-source current, and the surface temperature of the upper and lower bridges of the H-bridge unit. The host computer calculates the actual thermal resistance, actual maximum operating current, and maximum locked-rotor current of the MOSFET based on the steady-state temperature rise, drain-source voltage, and drain-source current; Test whether the MOSFET meets the SOA area limit range in the short-circuit state: Set the temperature test chamber to the specified temperature, select the load module's drive motor and connect it to the H-bridge unit, and set the controller module to drive the H-bridge unit with DC power. During the driving process, the controller module sets a relay switch to short-circuit the source of the upper bridge MOSFET of the H-bridge unit to ground and short-circuit the drain of the lower bridge MOSFET of the H-bridge unit to power. The host computer determines whether the MOSFET meets the SOA area limit range in the short-circuit state based on the drain-source peak voltage, short-circuit peak current, and short-circuit duration when shorting to power and shorting to ground. Test MOSFET switching loss: Set the temperature test chamber to the specified temperature, select the load module's drive motor and connect it to the H-bridge unit, set the controller module to drive current with different drive frequencies and duty cycles, and output the drive current to the drive motor using PWM modulation. The controller module outputs the drive current to the gate of each MOSFET in the H-bridge unit from weakest to strongest through the configured driver chip; the host computer calculates the switching loss based on the drain-source voltage waveform and drain-source current waveform when the MOSFET is turned on and off under different gate drive currents, as well as the turn-on and turn-off time.

2. The method according to claim 1, characterized in that The host computer calculates the actual thermal resistance, actual maximum operating current and maximum locked-rotor current of the MOSFET according to the steady-state temperature rise, drain-source voltage and drain-source current, including: The host computer calculates the steady-state temperature rise of the MOSFET , drain-source voltage and drain-source current to calculate the actual thermal resistance R of MOSFET JA ; The host computer calculates the actual thermal resistance R of MOSFET JA , MOSFET maximum withstand temperature , Maximum operating temperature and drain-source on-resistance Calculate the actual maximum operating current I of the MOSFET DMAX ; The host computer calculates the actual thermal resistance R of MOSFET JA , Steady-state temperature rise during normal operation , MOSFET maximum withstand temperature , Maximum operating temperature and drain-source on-resistance Calculate the actual maximum locked-rotor current.

3. The method according to claim 2, characterized in that The steady-state temperature rise during normal operation The temperature rise can be obtained by the following method: select the drive motor in the load module and connect it to the H-bridge unit. Set the controller module to drive the H-bridge with DC power. Use the thermal test unit to test the surface temperature of the upper and lower MOSFETs of the H-bridge unit. Test for more than half an hour. Test the temperature of the upper and lower MOSFETs of the H-bridge unit in steady state. The steady-state temperature rise during normal operation can be obtained. .

4. The method according to claim 1, wherein The host computer is based on the opening time of MOSFET , drain-source voltage waveform and drain-source current waveform to calculate the turn-on loss of MOSFET; wherein, the turn-on time of MOSFET is the drain-source voltage V DS Start to decrease to V DS Time that no longer changes; The host computer determines the MOSFET's off time , drain-source voltage waveform, drain-source current waveform and switching frequency Calculate the turn-off loss of MOSFET; wherein, the turn-off time of MOSFET V DS Starts to increase to V DS Time that no longer changes.

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