Automatic testing device and method for evaluating performance of power MOSFET (metal-oxide-semiconductor field effect transistor)

Abstract

The invention 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 supply module, a controller module, a driving module, a load module and a detection module. Based on the device, the turn-on voltage test, the gate source limit voltage test, the thermal resistance test, the short circuit test and the turn-on and turn-off waveform test of the MOSFET can be realized, the related working parameters of the MOSFET can be calculated according to the test data, the performance of the MOSFET can be comprehensively evaluated through comprehensive practical application, the device architecture is high in feasibility, the test conditions are easy to change, the devices are easy to replace, and the cost is low. The test efficiency is high; in addition, data used for evaluation of the device is convenient to obtain, the application value of the testing device is high, and the testing device has important significance in guiding model selection of the power MOSFET.

Description

Technical Field

[0001] The 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 transistor (MOSFET) has the advantages of fast switching speed, high input impedance, easy driving, and no secondary breakdown phenomenon. It is widely used in analog circuits and digital circuits. As the core component of modern power electronic systems, its performance parameters directly affect the efficiency, reliability and safety of the system. At present, the performance test of power MOSFET in the industry mainly relies on the specification data provided by the manufacturer, but these data are usually obtained in an idealized and static laboratory environment (such as constant temperature, fixed load, etc.), which is 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 technology and equipment have the following limitations:

[0003] 1. Simplified and fragmented test parameters: Existing test methods mostly focus on a single performance indicator (such as on-resistance, threshold voltage or switching time), and lack a comprehensive evaluation of the synergistic effect of multiple parameters. For example, thermal resistance testing is often independent of electrical performance testing, resulting in the inability to quantify the impact of temperature rise on the dynamic characteristics of the device. In addition, key parameters such as short-circuit withstand capability (SOA) and gate oxide layer limit voltage often need to rely on discrete equipment to complete the test process. 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: The existing test system is limited to the control of temperature conditions within the normal temperature range and lacks the ability to automate testing under a wide temperature range. Power MOSFETs are often exposed to extreme temperature shocks in automotive, industrial and other fields, and their threshold voltage, on-resistance and other parameters drift significantly with temperature. Existing test methods cannot dynamically simulate the impact of temperature changes on device performance, resulting in significant deviations between the data in the specification and the 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, and existing solutions mostly use manual data recording, which is time-consuming and prone to human errors. In addition, the measurement of dynamic parameters (such as switching loss) requires offline analysis of oscilloscopes, lacks real-time data processing and automated feedback mechanisms, and is difficult to meet batch testing needs.

[0006] 4. Limited dynamic load simulation capability: Existing simulation loads mostly use fixed resistors or simple electronic loads, which cannot accurately simulate transient loads in real applications (such as motor start and stop, short circuit faults, etc.). Especially in short circuit testing, existing equipment is difficult to capture the peak characteristics of drain-source voltage and current within the microsecond time scale, resulting in insufficient accuracy in SOA area assessment and inability to effectively predict the failure risk of devices under fault conditions.

[0007] 5. Insufficient system integration and scalability: Most test platforms are made up of discrete power supplies, controllers, and data acquisition units. The communication protocols of each module are not unified, and the system compatibility is poor. For example, the lack of a CAN bus or high-speed digital interface causes delays in test instructions and data feedback, making it difficult to achieve multi-parameter synchronous acquisition and closed-loop control. In addition, the existing architecture is difficult to adapt to MOSFETs of different packaging types, and device replacement requires redesign of fixtures and wiring, reducing test flexibility.

[0008] In summary, the current performance testing technology for MOSFET is relatively poor in comprehensiveness, and only tests a certain performance parameter of MOSFET. The test environment is often very complex, and it is impossible to fully evaluate the electrical performance parameters of MOSFET devices in actual application scenarios, which in turn affects its reliability and stability under different working conditions, and reduces the performance and safety of the system. Therefore, considering the performance parameters of MOSFET such as turn-on voltage, limit voltage, short-circuit characteristics, heat dissipation capacity, SOA area, etc. at different working environment temperatures, exploring a MOSFET automatic testing device and method with comprehensive test functions and easy implementation built according to actual application scenarios, and comprehensively evaluating the performance of MOSFET, is of great significance for selecting MOSFETs suitable for the circuit requirements of application scenarios. 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] Wherein, the host computer is connected to the controller module via the CAN bus, receives the test data transmitted by the controller module, 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, drives the simulated load according to the control instructions sent by the controller module, and tests 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 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; and the thermal test unit is used to monitor the surface temperature of the MOSFET to be tested.

[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 the control instruction of 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] On the other hand, the present invention provides a testing method for evaluating the performance of a power MOSFET based on the above device, the method comprising:

[0017] Test MOSFET gate-source turn-on voltage threshold: Determine the drain 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 And the leakage current test value I 0 Compare and obtain the gate-source turn-on voltage threshold;

[0018] Testing MOSFET gate-source limiting voltage: Determining the leakage current test value I 0 , determine 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 to connect with 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 as 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 ≥I 0 ; The host computer will I D with I 0 Compare and 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 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 stall 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 box to the specified temperature, select the load motor of the load module to connect with the H-bridge unit, and the controller module outputs DC power to drive the H-bridge unit through the driver chip. During the driving process, the controller module sets the relay switch to short-circuit the source of the upper bridge MOSFET of the H-bridge unit to the ground, and short-circuit the drain of the lower bridge MOSFET of the H-bridge unit to the power supply. 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 short-circuiting and short-circuiting.

[0021] Test MOSFET switching loss: set the temperature test chamber to the specified temperature, select the load motor of the load module to connect to the H-bridge unit, set the drive current with different drive frequencies and duty cycles on the controller module, and output the drive current to the load motor with PWM modulation. The controller module outputs the drive current from the weakest to the strongest to the gate of each MOSFET in the H-bridge unit through the configured drive 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.

[0022] Further, the host computer calculates the actual thermal resistance, the actual maximum operating current and the maximum stall current of the MOSFET according to the steady-state temperature rise, the drain-source voltage and the drain-source current, including:

[0023] The host computer calculates the steady-state temperature rise ΔT of the MOSFET 1 , drain-source voltage and drain-source current to calculate the actual thermal resistance R 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 environment 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 ΔT during normal operation 2 , MOSFET maximum withstand temperature MaxT j , Maximum operating environment temperature T C And the drain-source on-resistance R DS(on) Calculate the actual maximum stall current. Wherein, the steady-state temperature rise ΔT during normal operation 2 Obtained through:

[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. Test for more than half an hour to test the temperature of the upper and lower MOSFETs of the H-bridge in steady state. Get the steady-state temperature rise ΔT during normal operation. 2 .

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

[0028] The host computer determines 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 T of the MOSFET r is the drain-source voltage V DS Starts to decrease to V DS Time that no longer changes;

[0029] The host computer determines the MOSFET 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 the MOSFET is Tf 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 proposes an automatic test device for power MOSFET performance evaluation, the device driving module can be set to test the MOSFET alone, and can also be tested by forming the MOSFET into an H-bridge, which can realize the MOSFET's turn-on voltage test, gate-source limit voltage test, thermal resistance test, short circuit test, turn-on and turn-off waveform test and other projects; in addition, the device detection module adopts a combination of multiple load resistors and load motors, which can simulate a variety of different load scenarios and enrich the environment of MOSFET testing. The automatic test device provided by the present invention can comprehensively evaluate the performance of MOSFET based on actual application needs, and the device system architecture has high feasibility, easy to change test conditions, easy to replace devices, high test efficiency, convenient data acquisition for evaluation, high application value of the test device, and is of great significance for guiding the selection of power MOSFET.

[0031] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can 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 in conjunction with the accompanying drawings, wherein:

[0033] Figure 1 A schematic diagram of the structure of a MOSFET testing device provided by an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the 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 MOSFET Safe Operating Area;

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

[0038] Figure 6This is the waveform curve diagram for MOSFET turn-on;

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

[0040] The following describes the embodiments of the present invention by 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 only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

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

[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 the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position 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, and 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 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 comprises 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 test unit, which can detect the voltage, current, input and output waveforms of the driving module and the surface temperature of the MOSFET according to the instructions of the controller module, and transmit the sampled data to the controller. After receiving the signal, the controller interacts with the host computer to complete the calculation, collation and storage of the final test data. The signal acquisition unit is used to monitor the real-time gate-source voltage, drain-source voltage and drain-source current signals of the MOSFET unit; the waveform detection module is used to monitor the input and output voltage and current waveforms of the H-bridge unit in the driving module; and the thermal test unit is used to detect the surface temperature of the MOSFET of the H-bridge unit.

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

[0050] The method of 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 in a car 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 2 As 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 R is selected. 1=5Ω / 100W, the first power supply simulates the vehicle-mounted 12V system to provide the drain voltage, the gate is connected to the ground in parallel with a 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 stepping manner until the drain-source voltage and current no longer change, the controller sends instructions 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 instructions, and transmits them to the host computer through the controller, and the host computer can display the sampled voltage and current data in real time, and I D And the leakage current test value I 0 Compare, 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 I of the gate-source limit voltage 0 , determine the test time T for each step of the gate-source limit voltage test step1 In this embodiment, V GS =-20~20V, leakage current is I 0 =250μA, each step test time T step1 Set to 30 seconds. Taking the vehicle-mounted 12V system as an example, set the temperature test box to reach 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 drive module. In this embodiment, the drive current is 2A, and the power resistor R is selected. 1 =5Ω / 100W, the first power supply simulates the vehicle-mounted 12V system to provide drain voltage, the gate is connected to the ground in parallel with a 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 as T step1 , then turn off the gate voltage source, gradually increase the gate voltage from the threshold voltage in 1V steps, 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 ≥I 0 The controller sends instructions 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 instructions, 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 D with I 0Compare, obtain and record the gate-source limit voltage threshold. In this embodiment, the limit voltage V GS The limit voltage V at low temperature is 58V. GS It 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 resistors at both ends of the load motor are connected in parallel so that the H-bridge output current reaches the maximum simulated load current) and connects it to the H-bridge unit of the drive module. In this embodiment, the maximum temperature of the MOSFET is T j =175℃, the maximum current is 10A, and the power resistance is R=1Ω / 200W; the controller module is configured with a driver chip, and the driver chip outputs a DC drive H-bridge. The controller sends instructions to the detection module, and 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 hung 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 surface temperature of the MOSFET measured 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℃. The host computer can calculate the actual thermal resistance, actual maximum operating current and maximum stall current of MOSFET according to the steady-state temperature rise, drain-source voltage and current.

[0054] S4. Taking the vehicle-mounted 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 controller selects the load motor of the load module to be connected 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-mounted 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 electricity. The controller sends instructions 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 electricity / shorting to ground, and determines whether the MOSFET meets the SOA area limit range when shorting. 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 at room temperature short circuit is 60.934A, the shutdown time is 4.4μs, and V DS The peak value is 20.326V, the short-circuit current peak is 78.706A, the shutdown time is 7.2μs, 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 drive current with different drive frequencies and duty cycles according to the application requirements. Here, the drive frequency is set to 20KHz, the duty cycle is 50%, and the drive current is output to the load through the driver chip in the form of PWM modulation. The driver chip outputs the drive current to each MOSFET gate in the H-bridge unit, and the gate drive current is from the weakest to the strongest. Here, the drive 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 stall 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 steady-state temperature rise ΔT of the MOSFET.1 , drain-source voltage and drain-source current to calculate the actual thermal resistance R 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 environment 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 selects the relay switch, selects the load motor in the load module and connects it to the H-bridge unit of the drive 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 drive tube respectively, and tests the temperature of the upper and lower MOSFETs of the H-bridge drive tube in steady state for more than half an hour, obtains the steady-state temperature rise during normal operation and transmits it to the host computer. The host computer calculates the temperature of the upper and lower MOSFETs according to the actual thermal resistance R of the MOSFET. JA , Steady-state temperature rise ΔT during normal operation 2 , MOSFET maximum withstand temperature MaxT j , Maximum operating environment temperature T C And the drain-source on-resistance R DS(on) Calculate the actual maximum stall current.

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

[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 turn-on loss of MOSFET. Among them, the turn-on time of MOSFET is T r V DS Starts 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 GS and the drain-source current waveform I DData, 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 solution of the present invention rather than to limit it. 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 solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. An automatic test device for power MOSFET performance evaluation, characterized in that: It includes a host computer, a power module, a controller module, a drive module, a load module and a detection module; 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 driving 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 driving module includes a MOSFET to be tested and an H-bridge unit composed of the MOSFET to be tested, and drives a simulated load according to a control instruction sent by the controller module to test the MOSFET to be tested; The detection module collects the test data of the driving module according to the control instruction of the controller module, and transmits the test data to the controller module.

2. The automatic testing device according to claim 1, characterized in that: 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.

3. The automatic testing device according to claim 1, characterized in that: 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 driving module according to the control instruction of the host computer.

4. The automatic testing device according to claim 1, characterized in that: 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.

5. The automatic testing device according to claim 1, characterized in that: The power module, controller module, drive module, load module and detection module are all placed in a temperature test box.

6. A test method for evaluating the performance of a power MOSFET based on the device according to any one of claims 1 to 5, characterized in that: The method includes: Test MOSFET gate-source turn-on voltage threshold: Determine the drain 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 the 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 to connect with 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 as 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 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 stall 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 box to the specified temperature, select the load motor of the load module to connect with the H-bridge unit, set the controller module to drive the H-bridge unit with DC power, and set the relay switch in the controller module to short-circuit the source of the upper bridge MOSFET of the H-bridge unit to the ground during the driving process, and short-circuit the drain of the lower bridge MOSFET of the H-bridge unit to the power supply; the host computer determines whether the MOSFET meets the SOA area limit range in the short-circuit state according to the drain-source peak voltage, short-circuit peak current and short-circuit duration when shorting to power and shorting to the ground; Test MOSFET switching loss: set the temperature test chamber to the specified temperature, select the load motor of the load module to connect to the H-bridge unit, set the drive current with different drive frequencies and duty cycles on the controller module, and output the drive current to the load motor with PWM modulation. The controller module outputs the drive current from the weakest to the strongest to the gate of each MOSFET in the H-bridge unit through the configured drive 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.

7. The method according to claim 6, characterized in that The host computer calculates the actual thermal resistance, the actual maximum operating current and the maximum stall current of the MOSFET according to the steady-state temperature rise, the drain-source voltage and the drain-source current, including: 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 ; The host computer calculates the actual thermal resistance R of MOSFET JA , MOSFET maximum withstand temperature MaxT j , Maximum operating environment temperature T C And the drain-source on-resistance R DS(on) 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 ΔT2 during normal operation, MOSFET maximum withstand temperature MaxT j , Maximum operating environment temperature T C And the drain-source on-resistance R DS(on) Calculate the actual maximum stall current.

8. The method according to claim 7, characterized in that The steady-state temperature rise ΔT2 during normal operation is obtained by: selecting a load motor in the load module to connect to the H-bridge unit, setting a DC drive H-bridge in the controller module, and testing the surface temperatures of the upper and lower MOSFETs of the H-bridge unit respectively through a thermal test unit, and testing the temperature of the upper and lower MOSFETs of the H-bridge unit in steady state for more than half an hour to obtain a steady-state temperature rise ΔT2 during normal operation.

9. The method according to claim 6, characterized in that The host computer determines 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 T of the MOSFET r is the drain-source voltage V DS Starts to decrease to V DS Time that no longer changes; The host computer determines the MOSFET 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 the MOSFET is T f V DS Starts to increase to V DS Time that no longer changes.

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