Limited current adjustable testing device

Abstract

The utility model relates to the technical field of electronic circuits, and discloses a current-limiting adjustable testing device, which comprises a current-limiting protection circuit, a first switching circuit, a second switching circuit, an adjustable gate driving resistor array and a voltage conversion circuit, and is characterized in that when short-circuit parameter testing is carried out on a tested power device, the second switching circuit is controlled to be switched off, and the adjustable gate driving resistor array is controlled to be switched on; and determining a current limiting value according to the short-circuit current value of the tested power device, and adjusting the voltage value of the first driving power supply according to the voltage-current curve and the current limiting value so as to carry out current limiting on the loop of the testing device. According to the utility model, the tested power device is measured under the condition that the precision resistor is not connected in series, the current limiting protection circuit is used for adjusting the current limiting of the whole testing device, the testing device is not damaged when the tested power device is short-circuited, the measurement error caused by the series connection of the precision resistor is avoided, and the measurement accuracy is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of power electronics, in particular to a testing device with adjustable current limiting. Background Art

[0002] The third generation semiconductor material high-power devices are widely used in the market, but in their dynamic parameter tests (such as short-circuit parameter tests), there are often high voltage and high current. For example, the 600V, 650V, 800V, 1200V MOSFET products currently used in domestic automobiles, or the 1700V, 2500V and other high-voltage IGBT products used in power electronics, have a short-circuit current capability of up to 5000A or more, a short-circuit time of 10us, and an instantaneous short-circuit energy of up to 10 joules or more. If the device under test (DUT) fails or is damaged during the test, the instantaneous short-circuit energy will continue to increase, exceeding the system design indicators and damaging the test system. In severe cases, there is also the risk of explosion and burning of electronic components and high-voltage capacitors.

[0003] The prior art converts the bus current value into a voltage signal through a combination of a precision resistor or a current transformer and an op amp circuit, and then transmits the voltage signal to a control chip such as an MCU or FPGA through an analog-to-digital converter. The control chip compares the preset current upper limit value according to the preset program instruction, and sends a control signal to execute the action of closing the bus main switch device when the upper limit is exceeded. However, this method has a complex circuit. If a precision resistor is used to sample the current value, the internal resistance of the large current loop is increased, affecting the authenticity of the test result; if a current transformer is used to sample the current, there are problems with accuracy and zero drift, and the transformer will be saturated and cannot be used in the case of large current. Regardless of the current sampling method used, an external op amp and an analog-to-digital converter circuit are required, which will result in bandwidth and conversion time limitations, and the control chip needs to process the calculation. The action time of the bus switch device is generally us level for MOSFET or IGBT and ms level for relays. If it is a high-power relay, the action time can be as high as tens of ms, resulting in increased errors. The prior art increases the error of the measurement result when solving the problem of short circuit of the device under test and damage to the test device. Utility Model Content

[0004] In view of this, the utility model provides a test device with adjustable current limiting to solve the problem that the test device is not damaged when a power device under test is short-circuited but the error of the measurement result increases.

[0005] In a first aspect, the utility model provides a current limiting adjustable test device, comprising: a current limiting protection circuit, a first switch circuit, a second switch circuit, an adjustable gate drive resistor array, and a voltage conversion circuit, wherein:

[0006] A current limiting protection circuit, wherein the first driving signal is input to the input terminal, the positive power supply terminal is connected to the external first driving power supply, the negative power supply terminal is connected to the first ground terminal, and the output terminal is connected to the control terminal of the first switch circuit, and is used to adjust the voltage of the control terminal of the first switch circuit according to the voltage value of the input first driving power supply, so as to adjust the current limiting value of the test device;

[0007] A first switch circuit, a first end of which is connected to the positive electrode of an external power supply, and a second end of which is connected to the first end of the power device under test and the first end of the second switch circuit;

[0008] A second switch circuit, a second end of which is connected to the negative electrode of the external power supply, the second end of the power device under test, and the second grounding end, and the second end of the power device under test is connected to the third grounding end;

[0009] An adjustable gate drive resistor array, a first end of which is connected to the control end of the power device under test, and a second end of which is connected to the output end of the voltage conversion circuit, and which controls the speed of turning on and off the power device under test by controlling the current change rate during measurement;

[0010] A voltage conversion circuit, wherein the second driving signal is input to the input terminal, the positive power supply terminal is connected to the external second driving power supply, the negative power supply terminal is connected to the external third driving power supply, the second driving power supply and the third driving power supply are both connected to the third ground terminal, and the voltage conversion circuit is used to convert the second driving signal into a driving voltage;

[0011] When the second switch circuit is closed and the power device under test is not connected in series with the circuit or is in a cut-off state, current calibration is performed on the first switch circuit to obtain a voltage-current curve of the first switch circuit;

[0012] When a short-circuit parameter test is performed on the power device under test, the second switch circuit is controlled to be disconnected, the current limiting value is determined according to the short-circuit current value of the power device under test, and the voltage value of the first driving power supply is adjusted according to the voltage-current curve and the current limiting value to limit the current of the circuit of the test device.

[0013] The utility model provides a test device with adjustable current limit, which measures the power device under test without connecting a precision resistor in series. The current limiting of the entire test device is adjusted by a current limiting protection circuit to ensure that the short circuit of the power device under test does not damage the test device, while avoiding the measurement error caused by the series connection of the precision resistor, thereby improving the measurement accuracy.

[0014] In an optional implementation, the current limiting protection circuit includes:

[0015] The first operational amplifier has an input terminal inputting a first driving signal, a positive power supply terminal connected to an external first driving power supply, a negative power supply terminal connected to a first ground terminal, and an output terminal connected to a control terminal of a first switch circuit.

[0016] The utility model provides a test device with adjustable current limiting, in which the voltage value of the first driving power supply directly affects the gain voltage VGE of the first operational amplifier, thereby affecting the current limiting of the test device, so that the current limiting of the test device can be adjusted according to the short-circuit current of the power device under test, thereby ensuring that the test device is not damaged when the power device under test is short-circuited.

[0017] In an optional implementation, the first switch circuit includes:

[0018] The triode is connected to the positive pole of the external power supply, the second end of which is connected to the first end of the power device under test and the first end of the second switch circuit, and the control end of which is connected to the output end of the current limiting protection circuit.

[0019] The utility model provides a test device with adjustable current limiting, which achieves the purpose of adjusting the current limiting value of the device under test by connecting the input end of the transistor with the output end of the current limiting protection circuit, adjusting the output voltage value of the current limiting protection circuit, controlling the transistor gain voltage, and further adjusting the current limiting value inside the test device.

[0020] In an optional implementation, the second switch circuit includes: a single-pole single-throw relay.

[0021] The utility model provides a test device with adjustable current limit, which switches the working state of the device under test by controlling the on-off state of a single-pole single-throw relay. For example, when the single-pole single-throw relay is closed, the device under test is in a calibration state, and the voltage and current curve of the first switch circuit can be calibrated; when the single-pole single-throw relay is disconnected, the device under test is in a measuring state, and the dynamic parameters of the power device under test in a short-circuit state can be measured, thereby ensuring the accuracy of the measurement result.

[0022] In an optional implementation, the adjustable gate drive resistor array includes: a first resistor array branch and a second resistor array branch connected in reverse parallel.

[0023] In an optional embodiment, the first resistor array branch includes: a first diode and a first variable resistor, wherein the first diode has an anode connected to the output end of the voltage conversion circuit and a cathode connected to the first end of the first variable resistor; the first variable resistor has a second end connected to the control end of the power device under test.

[0024] In an optional embodiment, the second resistor array branch includes: a second diode and a second variable resistor, wherein the cathode of the second diode is connected to the output end of the voltage conversion circuit, and the anode of the second diode is connected to the first end of the second variable resistor; the second variable resistor has a second end connected to the control end of the power device under test.

[0025] The utility model provides a test device with adjustable current limit, in which the adjustable gate drive resistor array controls the on-off speed of the voltage conversion circuit by adjusting the current at the output end of the voltage conversion circuit, thereby ensuring the on-off speed of the voltage conversion circuit and improving the test efficiency without damaging the test device.

[0026] In an optional implementation, the voltage conversion circuit includes:

[0027] The second operational amplifier has an input terminal inputting a second driving signal, a positive power supply terminal connected to an external second driving power supply, a negative power supply terminal connected to an external third driving power supply, and an output terminal connected to an adjustable gate driving resistor array.

[0028] The utility model provides a test device with adjustable current limit, wherein the second operational amplifier converts the second driving signal into a driving voltage, and inputs the driving voltage into the control terminal of the power device under test, so that the power device under test enters a working state, thereby facilitating the measurement of its dynamic parameters.

[0029] In an optional embodiment, the current limiting adjustable testing device further includes:

[0030] A first resistor, whose first end is connected to the output end of the current limiting protection circuit and whose second end is connected to the control end of the first switch circuit, is used to adjust the current at the output end of the current limiting protection circuit to control the on-off speed of the current limiting protection circuit.

[0031] The utility model provides a test device with adjustable current limiting, which adjusts the on-off speed of the current limiting protection circuit by connecting a first resistor in series at the output end of the current limiting protection circuit, thereby improving the working efficiency of the test device.

[0032] In an optional embodiment, the current limiting adjustable testing device further includes:

[0033] A power supply module, whose positive electrode is connected to the first end of the first switch circuit and whose negative electrode is connected to the second grounding end, is used to provide power for the current limiting adjustable test device.

[0034] In an optional embodiment, the current limiting adjustable test device also includes: a first capacitor and a second capacitor, wherein the first capacitor has a first end connected to the second end of the first switching circuit, and a second end connected to the second end of the second capacitor and the second ground end; the second capacitor has a first end connected to the positive pole of the power module, and a second end connected to the negative pole of the power module.

[0035] The current-limiting adjustable test device provided by the utility model stores electric energy through two capacitors to ensure the normal use of the power module. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 It is a structural schematic diagram of a current limiting adjustable test device according to an embodiment of the utility model;

[0038] Figure 2 It is an equivalent circuit diagram of a current-limiting adjustable test device according to an embodiment of the utility model when performing a calibration function;

[0039] Figure 3 It is a voltage-current curve diagram obtained when a current-limiting adjustable test device according to an embodiment of the utility model performs a calibration function;

[0040] Figure 4 It is an equivalent circuit diagram of a current-limiting adjustable test device according to an embodiment of the utility model when performing a short-circuit measurement function;

[0041] Figure 5 It is a timing diagram of a power device under test not being damaged when a short-circuit parameter test is performed by a current-limit adjustable test device according to an embodiment of the utility model;

[0042] Figure 6 It is an equivalent circuit diagram of a measurement loop when a short-circuit parameter test is performed by a current-limit adjustable test device according to an embodiment of the utility model and a power device under test fails and shorts;

[0043] Figure 7 It is a timing diagram of damage to a power device under test when a short-circuit parameter test is performed by a current-limit adjustable test device according to an embodiment of the utility model;

[0044] Figure 8 It is a structural diagram of a specific circuit of a current limiting adjustable test device according to an embodiment of the utility model. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the utility model.

[0046] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are 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 operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0047] In the description of the present utility model, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0048] The embodiment of the utility model provides a test device with adjustable current limiting, which ensures that a short circuit of a power device under test does not damage the test device and improves the measurement accuracy through a current limiting protection circuit.

[0049] According to an embodiment of the utility model, a test device embodiment with adjustable current limiting is provided, such as Figure 1 As shown, it includes: a current limiting protection circuit 01, a first switch circuit 02, a second switch circuit 03, an adjustable gate drive resistor array 04, and a voltage conversion circuit 05.

[0050] like Figure 1 As shown, the current limiting protection circuit 01 has an input terminal that inputs a first driving signal, a positive power supply terminal that is connected to an external first driving power supply HVCC, a negative power supply terminal that is connected to a first ground terminal H_GND, and an output terminal that is connected to a control terminal of a first switching circuit 02, and is used to adjust the voltage of the control terminal of the first switching circuit 02 according to the voltage value of the input first driving power supply HVCC to adjust the current limiting value of the test device.

[0051] Exemplarily, the first driving power supply HVCC is an adjustable low-voltage isolated driving power supply. The voltage value of the first driving power supply HVCC can be set through the host computer and the control loop as needed. The current limiting protection circuit uses a gate driving chip. When the first driving signal is at a high level, its output voltage value is equal to the voltage value of the first driving power supply HVCC. The output voltage value of the current limiting protection circuit serves as the driving voltage of the first switching circuit, which can adjust the current value of the first switching circuit and indirectly adjust the current limiting value of the test device.

[0052] like Figure 1 As shown, the first switch circuit 02 has a first end connected to the positive electrode of the external power supply, and a second end connected to the first end of the power device under test and the first end of the second switch circuit 03.

[0053] like Figure 1 As shown, the second switch circuit 03 has a second end connected to the negative electrode of the external power supply, the second end of the power device under test, and the second ground end P_GND, and the second end of the power device under test is connected to the third ground end VG_GND.

[0054] like Figure 1 As shown, the adjustable gate drive resistor array 04 has a first end connected to the control end of the power device under test, and a second end connected to the output end of the voltage conversion circuit 05, which controls the speed of turning on and off the power device under test by controlling the current change rate during measurement.

[0055] like Figure 1 As shown, the voltage conversion circuit 05 has an input terminal that inputs the second driving signal, a positive power supply terminal that is connected to an external second driving power supply VG+, and a negative power supply terminal that is connected to an external third driving power supply VG-. The second driving power supply VG+ and the third driving power supply VG- are both connected to the third ground terminal VG_GND, and are used to convert the second driving signal into a driving voltage.

[0056] Exemplarily, the second driving power source VG+ and the third driving power source VG- are adjustable low-voltage isolated driving power sources, and their voltage values ​​can be set through the host computer and the control loop as needed.

[0057] Specifically, the test device of this embodiment involves two states, which are as follows:

[0058] (1) Calibration status

[0059] When the second switch circuit 03 is closed and the power device under test is not connected in series with the circuit or is in a cut-off state, the current calibration is performed on the first switch circuit 02 to obtain a voltage-current curve of the first switch circuit 02 .

[0060] When the current curve calibration function is used, when the second switch circuit 03 is closed and the power device under test is not connected in series with the circuit or is in the cut-off state, the equivalent circuit of the test device is as follows: Figure 2 As shown, at the beginning of calibration, the first drive signal S1 is always output at a high level, so that the current limiting protection circuit is always in a conducting state. The current limiting protection circuit uses a gate drive chip. When the first drive signal is at a high level, the output value is the voltage value of the first drive power supply HVCC, and the voltage gain of the current limiting protection circuit is the first drive power supply HVCC. The voltage value of the first drive power supply HVCC is continuously adjusted from small to large through software control, and at the same time, a current sensor is connected in series in the loop of the test device to continuously sample the current value. Figure 2 The current sensor is connected in series to the branch where the second switch circuit is located to collect the current of the second switch circuit. This is only an example, but not limited to this. The current value collected by the loop current sensor increases as the voltage value of the first drive power supply HVCC increases. The corresponding relationship between the current value and the first drive power supply HVCC is processed to obtain the following: Figure 3 The voltage-current curve is shown in the figure. Figure 3 The voltage-current curve shown is saved in the Flash or SRAM memory chip of the hardware control circuit, so that the saved data can be called for subsequent current limiting operations. The calibration function is only used when a new machine leaves the factory or when the customer performs regular inspections. This function is not required for normal short-circuit testing.

[0061] (2) Test status

[0062] When a short-circuit parameter test is performed on the power device under test, the second switch circuit 03 is controlled to be disconnected, the current limiting value is determined according to the short-circuit current value of the power device under test, and the voltage value of the first driving power supply is adjusted according to the voltage-current curve and the current limiting value to limit the current of the loop of the test device.

[0063] When the short-circuit parameter test is performed on the power device under test, the second switch circuit 03 is controlled to be disconnected, and the equivalent circuit diagram is as follows: Figure 4 To ensure that the test device is not damaged, it is necessary to set the voltage value of the first driving power supply according to the current value of the short-circuit current of the power device under test. For example, when the short-circuit current of the power device under test is 50A, the current limiting protection value of the control system measurement loop is 60A (to ensure safe measurement, the current limiting value of the measuring device will leave some margin, here 20% of the short-circuit current is used as the margin, only as an example, but not limited to this), and the voltage-current curve is obtained, as shown Figure 3 As shown by the dotted line, when the current limiting value is 60A, the gain voltage of the current limiting protection circuit is 6.2V. By setting the first driving power supply HVCC to 6.2V, the purpose of current limiting of the test device loop is achieved.

[0064] The three terminals VGS, VDS, and IDS of the current sensor IDS are connected to the oscilloscope measurement port (OSC) for testing related data and waveforms. In this embodiment, the connection method in the figure is only used as an example, but it is not limited to this. It can achieve the measurement of related data and waveforms. Under normal circumstances, that is, when the power device under test is not damaged, the timing diagram of the short-circuit parameter test is as follows: Figure 5 As shown; if the power device under test fails and short-circuits during the short-circuit parameter test, the measurement circuit is simplified to Figure 6 , the first and second terminals of the power device under test DUT are short-circuited, and the current will increase instantaneously along the dotted line direction in the figure. When the current increases to the maximum current limited by the current limiting protection circuit, the current limiting protection will be triggered, such as Figure 7 The timing diagram at this time is shown to avoid damaging the test equipment.

[0065] The utility model provides a test device with adjustable current limit, which measures the power device under test without connecting a precision resistor in series. The current limiting of the entire test device with adjustable current limit is adjusted by the current limiting protection circuit 01, which ensures that the short circuit of the power device under test does not damage the test device, while avoiding the measurement error caused by the series precision resistor, thereby improving the measurement accuracy.

[0066] In some optional embodiments, such as Figure 8 As shown, the current limiting protection circuit 01 includes:

[0067] The first operational amplifier A1 has a first drive signal S1 inputted into its input terminal, a positive power supply terminal connected to an external first drive power supply HVCC, a negative power supply terminal connected to a first ground terminal H_GND, and an output terminal connected to a control terminal of the first switch circuit 02. The characteristic curve of the switch device in the first switch circuit is utilized: the VGE-ICE curve, and the gain voltage Vge of the switch device is reasonably set, so that the IGBT switch works in an amplified state, and the maximum through current is clamped by its own characteristics, thereby achieving the function of current limiting protection of the measurement circuit.

[0068] The utility model provides a test device with adjustable current limiting, in which the voltage value of the first driving power supply directly affects the VGE voltage of the first operational amplifier, thereby affecting the current limiting of the test device, so that the current limiting of the test device can be adjusted according to the short-circuit current of the power device under test, thereby ensuring that the test device is not damaged when the power device under test is short-circuited.

[0069] In some optional embodiments, such as Figure 8 As shown, the first switch circuit 02 includes:

[0070] The transistor Q1 is connected to the positive electrode of the external power supply, has a second end connected to the first end of the power device under test DUT and the first end of the second switch circuit 03 , and has a control end connected to the output end of the current limiting protection circuit 01 .

[0071] The current limiting adjustable test device provided by the utility model is connected to the current limiting protection circuit 01 through a transistor, thereby amplifying the output current of the current limiting protection circuit 01 and ensuring that the device under test has a larger current limiting value when the first driving power supply is limited.

[0072] In some optional embodiments, such as Figure 8 As shown, the second switch circuit 03 includes: a single-pole single-throw relay K1.

[0073] The utility model provides a test device with adjustable current limiting, which switches the working state of the device under test through a single-pole single-throw relay. When the single-pole single-throw relay is closed, the device under test is in a calibration function, and when the single-pole single-throw relay is disconnected, the device under test is in a measurement state, thereby ensuring the accuracy of the measurement result.

[0074] In some optional embodiments, such as Figure 8 As shown, the adjustable gate drive resistor array 04 includes: a first resistor array branch and a second resistor array branch connected in reverse parallel.

[0075] In some optional embodiments, such as Figure 8 As shown, the first resistor array branch includes: a first diode D1 and a first variable resistor R_P, wherein the first diode D1 has an anode connected to the output end of the voltage conversion circuit 05, and a cathode connected to the first end of the first variable resistor R_P; the first variable resistor R_P has a second end connected to the control end of the power device under test DUT.

[0076] In some optional embodiments, such as Figure 8 As shown, the second resistor array branch includes: a second diode D2 and a second variable resistor R_N, wherein the cathode of the second diode D2 is connected to the output end of the voltage conversion circuit 05, and the anode of the second diode D2 is connected to the first end of the second variable resistor R_N; the second variable resistor R_N, the second end of which is connected to the control end of the power device under test DUT.

[0077] Optionally, the first variable resistor and the second variable resistor may include sliding resistors, which is only an example but not limited to this.

[0078] The utility model provides a test device with adjustable current limiting, in which the adjustable gate drive resistor array 04 controls the on-off speed of the voltage conversion circuit 05 by adjusting the current at the output end of the voltage conversion circuit 05, thereby ensuring the on-off speed of the voltage conversion circuit 05 and improving the test efficiency without damaging the test device.

[0079] In some optional embodiments, such as Figure 8 As shown, the voltage conversion circuit 05 includes:

[0080] The second operational amplifier A2 has its input terminal inputting the second driving signal VG, its positive power supply terminal connected to the external second driving power supply VG+, its negative power supply terminal connected to the external third driving power supply VG-, and its output terminal connected to the adjustable gate driving resistor array 04. The second driving power supply VG+ and the third driving power supply VG- are both connected to the third ground terminal VG_GND, and the third ground terminal VG_GND is also connected to the second terminal of the power device under test DUT.

[0081] The utility model provides an adjustable current limiting test device, which converts a second driving signal into a driving voltage through a second operational amplifier and inputs the voltage into a control terminal of a power device under test, so that the power device under test enters a working state, thereby facilitating measurement of its dynamic parameters.

[0082] In some optional embodiments, such as Figure 8 As shown, the current limiting adjustable test device also includes:

[0083] The first resistor R has a first end connected to the output end of the current limiting protection circuit 01 and a second end connected to the control end of the first switch circuit 02, and is used to adjust the current at the output end of the current limiting protection circuit 01 to control the on-off speed of the current limiting protection circuit 01.

[0084] The current limiting adjustable test device provided by the utility model adjusts the on-off speed of the current limiting protection circuit 01 by connecting a first resistor in series to the output end of the current limiting protection circuit 01, thereby improving the working efficiency of the test device.

[0085] In some optional embodiments, such as Figure 8 As shown, the current limiting adjustable test device also includes:

[0086] The power module HV_POWER, whose positive electrode is connected to the first end of the first switch circuit 02 and whose negative electrode is connected to the second ground terminal P_GND, is used to provide power for the current-limiting adjustable test device. Optionally, the power module can be a programmable power supply, but this is only an example and is not intended to be limiting.

[0087] In some optional embodiments, such as Figure 8 As shown, the current limiting adjustable test device also includes: a first capacitor C1 and a second capacitor C2, wherein the first capacitor C1, the first end of which is connected to the second end of the first switch circuit 02, and the second end of which is connected to the second end of the second capacitor C2 and the second ground terminal P_GND; the second capacitor C2, the first end of which is connected to the positive electrode of the power module HV_POWER, and the second end of which is connected to the negative electrode of the power module HV_POWER.

[0088] The current-limiting adjustable test device provided by the utility model stores electric energy through two capacitors to ensure the normal use of the power module.

[0089] Although the embodiments of the present invention are described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A test device with adjustable current limiting, characterized in that: include: A current limiting protection circuit, a first switch circuit, a second switch circuit, an adjustable gate drive resistor array, and a voltage conversion circuit, wherein: A current limiting protection circuit, wherein an input terminal thereof inputs a first driving signal, a positive power supply terminal thereof is connected to an external first driving power supply, a negative power supply terminal thereof is connected to a first ground terminal, and an output terminal thereof is connected to a control terminal of the first switching circuit, and is used for adjusting a voltage at the control terminal of the first switching circuit according to a voltage value of the input first driving power supply, so as to adjust a current limiting value of the testing device; A first switch circuit, a first end of which is connected to the positive electrode of an external power supply, and a second end of which is connected to the first end of the power device under test and the first end of the second switch circuit; A second switch circuit, a second end of which is connected to the negative electrode of the external power supply, the second end of the power device under test, and the second grounding end, and the second end of the power device under test is connected to the third grounding end; An adjustable gate drive resistor array, a first end of which is connected to the control end of the power device under test, and a second end of which is connected to the output end of the voltage conversion circuit, and which controls the speed of turning on and off the power device under test by controlling the current change rate during measurement; A voltage conversion circuit, wherein an input terminal thereof inputs a second driving signal, a positive power supply terminal thereof is connected to an external second driving power supply, a negative power supply terminal thereof is connected to an external third driving power supply, and the second driving power supply and the third driving power supply are both connected to a third ground terminal, and the voltage conversion circuit is used to convert the second driving signal into a driving voltage; When the second switch circuit is closed and the power device under test is not connected in series with the circuit or is in a cut-off state, current calibration is performed on the first switch circuit to obtain a voltage-current curve of the first switch circuit; When a short-circuit parameter test is performed on the power device under test, the second switch circuit is controlled to be disconnected, a current limiting value is determined according to the short-circuit current value of the power device under test, and the voltage value of the first driving power supply is adjusted according to the voltage-current curve and the current limiting value to limit the current of the circuit of the testing device.

2. The current limiting adjustable test device according to claim 1, characterized in that: The current limiting protection circuit comprises: The first operational amplifier has an input terminal inputting a first driving signal, a positive power supply terminal connected to an external first driving power supply, a negative power supply terminal connected to a first ground terminal, and an output terminal connected to a control terminal of the first switch circuit.

3. The current limiting adjustable test device according to claim 1, characterized in that: The first switch circuit comprises: A triode is connected to the positive pole of an external power supply, a second end of which is connected to the first end of the power device under test and the first end of the second switch circuit, and a control end of which is connected to the output end of the current limiting protection circuit.

4. The current limiting adjustable test device according to claim 1, characterized in that: The second switch circuit includes: a single-pole single-throw relay.

5. The current limiting adjustable test device according to claim 1, characterized in that: The adjustable gate drive resistor array includes: a first resistor array branch and a second resistor array branch connected in reverse parallel.

6. The current limiting adjustable test device according to claim 5, characterized in that: The first resistor array branch includes: a first diode and a first variable resistor, wherein: a first diode, an anode of which is connected to the output end of the voltage conversion circuit, and a cathode of which is connected to the first end of the first variable resistor; A first variable resistor, a second end of which is connected to the control end of the power device under test.

7. The current limiting adjustable test device according to claim 5, characterized in that: The second resistor array branch includes: a second diode and a second variable resistor, wherein: a second diode, a cathode of which is connected to the output end of the voltage conversion circuit, and an anode of which is connected to the first end of the second variable resistor; A second variable resistor, a second end of which is connected to the control end of the power device under test.

8. The current limiting adjustable test device according to claim 1, characterized in that: The voltage conversion circuit comprises: The second operational amplifier has an input terminal inputting the second driving signal, a positive power supply terminal connected to an external second driving power supply, a negative power supply terminal connected to an external third driving power supply, and an output terminal connected to the adjustable gate driving resistor array.

9. The current limiting adjustable test device according to claim 1, characterized in that: Also includes: A first resistor, whose first end is connected to the output end of the current limiting protection circuit and whose second end is connected to the control end of the first switch circuit, is used to adjust the current at the output end of the current limiting protection circuit to control the on-off speed of the current limiting protection circuit.

10. The current limiting adjustable test device according to claim 1, characterized in that: Also includes: A power supply module, whose positive electrode is connected to the first end of the first switch circuit and whose negative electrode is connected to the second grounding end, is used to provide power for the test device with adjustable current limiting.

11. The current limiting adjustable test device according to claim 10, characterized in that: Also includes: A first capacitor and a second capacitor, wherein: A first capacitor, a first end of which is connected to the second end of the first switch circuit, and a second end of which is connected to the second end of the second capacitor and a second ground end; A second capacitor has a first end connected to the positive electrode of the power module and a second end connected to the negative electrode of the power module.

Images