A power device characteristic test circuit and method

Abstract

The application relates to the field of power electronics, and discloses a power device characteristic test circuit and method, which integrates a switching time test device and an avalanche breakdown test device, reduces the equipment investment cost, reduces the debugging time of the tested power device at the initial test stage, reduces the overall test time, speeds up the test time of mass production products, and reduces the test cost.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and more specifically to a power device characteristic testing circuit and method. Background Technology

[0002] Currently, avalanche breakdown testers and switching time testers on the market are two independent measurement systems. When customers need to test these two parameters simultaneously, separate workstations are required, resulting in long testing times and high equipment investment. Furthermore, avalanche breakdown testers require clamping when measuring IGBT devices to prevent excessive energy from causing breakdown. The current method involves connecting a TVS diode or Zener diode in parallel across the drain and source (or collector and emitter) terminals of the device under test. Since different products require different clamping voltages, the initial debugging phase of new product introductions is quite troublesome: hand soldering makes replacement and debugging difficult and can easily damage the tester and devices; using a TVS matrix can effectively solve the need for adjustable clamping voltage, but a matrix TVS requires many different models of TVS diodes, increasing costs. Additionally, the breakdown voltage of the same model of TVS diodes varies significantly, making it difficult to precisely adjust the clamping voltage. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the problem that the power device switching time test system and the avalanche breakdown test system are independent in the prior art, thereby providing a power device characteristic test circuit and method.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] In a first aspect, the present invention provides a power device characteristic testing circuit, comprising: a first switching circuit, a second switching circuit, a power inductor, an adjustable gate drive resistor array, and an operational amplifier circuit, wherein the first switching circuit is connected in parallel with an external power supply; the second switching circuit is connected in parallel with the power inductor to form a first branch; a first terminal of the first branch is connected to a first terminal of the first switching circuit, and a second terminal of the first branch is connected to a first terminal of the power device; the power device has a control terminal connected to a first terminal of the adjustable gate drive resistor array, and its second terminal and the second terminal of the first switching circuit are both connected to a first ground terminal, and its second terminal is also connected to a second ground terminal; the adjustable gate drive resistor array... The first switch circuit is connected to the second switch circuit, and its second power supply is connected to the output of the operational amplifier circuit. The operational amplifier circuit has its input connected to the drive signal source, its first power supply connected to the first drive power supply, and its second power supply connected to the second drive power supply. Both the first and second drive power supplies are connected to the second ground terminal. When performing a switching time test, the first switch circuit is controlled to be disconnected, and the output state of the operational amplifier circuit drive signal source is adjusted by controlling the on / off state of the second switch circuit to measure the switching time of the power device. When performing an avalanche breakdown test, the first switch circuit is controlled to be turned on and the second switch circuit is turned off, and the output state of the operational amplifier circuit drive signal source is adjusted to cause the power device to undergo avalanche breakdown.

[0006] The test circuit provided by this invention integrates an avalanche tester and a switching time tester. When it is necessary to measure these two parameters of a power device, it can reduce equipment investment costs, reduce the debugging time of the power device under test in the initial stage of testing, and reduce the overall testing time, thereby accelerating the testing time of mass-produced products and reducing testing costs.

[0007] In one optional embodiment, the first switching circuit includes a first single-pole single-throw relay and a first diode, wherein the cathode of the first diode is connected to the first terminal of the second switching circuit and the first terminal of the external power supply through the first single-pole single-throw relay, the anode of the first diode is connected to the second terminal of the power device, and the anode, the second terminal of the power device, and the external power supply are all connected to the second ground terminal.

[0008] The test circuit provided by this invention can, in the event of an avalanche breakdown, have its first switching circuit act as a direct current circuit, forming a freewheeling loop for the power inductor.

[0009] In one alternative embodiment, the second switching circuit includes: a first controllable switch, the first end of which is connected to the first end of the first switching circuit and an external power supply, and the second end of which is connected to the first end of the power device for freewheeling current to the power inductor.

[0010] The test circuit provided by this invention uses an IGBT without a body diode as the second switching circuit, which is a power inductor freewheeling circuit.

[0011] In one alternative implementation, the adjustable gate drive resistor array includes a first resistor array branch and a second resistor array branch connected in reverse parallel.

[0012] The test circuit provided by this invention uses an adjustable gate drive resistor array to control the turn-on and turn-off speed of power devices.

[0013] In one optional embodiment, the system further includes a power supply module comprising: a support capacitor, a second controllable switch, and a programmable power supply. The support capacitor has a first terminal connected to a first terminal of the second controllable switch, and a second terminal connected to a second terminal of the first switching circuit and a first ground terminal. The second controllable switch has two terminals connected to a first terminal of the first branch. The programmable power supply is connected in parallel with the support capacitor and is used to provide a test voltage for the power device.

[0014] In one optional implementation, it further includes: a clamping circuit, the power supply terminal of which is connected to an external isolated power supply, the first terminal of which is connected to the second terminal of the first branch, the second terminal of which is connected to the control terminal of the power device, and the third terminal of which is connected to the second ground terminal, for absorbing excess current in the circuit and clamping the voltage across the power device to the avalanche breakdown voltage during the avalanche breakdown test.

[0015] The test circuit provided by this invention can protect the power device under test during avalanche breakdown testing by clamping the circuit, preventing the power device from being damaged by avalanche breakdown due to excessive energy.

[0016] In one optional embodiment, the clamping circuit includes: a second single-pole single-throw relay, a third single-pole single-throw relay, a fourth single-pole single-throw relay, a second diode, and a third diode. The cathode of the second diode is connected to the positive terminal of an external isolation power supply, and its anode is connected to a first terminal of the power device via the second single-pole single-throw relay. The anode of the third diode is connected to the negative terminal of the external isolation power supply, and its cathode is connected to the control terminal of the power device via the third single-pole single-throw relay. Its cathode is also connected to a second ground terminal via the fourth single-pole single-throw relay.

[0017] The test circuit provided by this invention uses diodes to prevent reverse power supply from externally connected isolation power, which could damage the power devices.

[0018] Secondly, the present invention provides a method for testing the characteristics of a power device, comprising: when performing a switching time test, controlling a first switching circuit to be disconnected, and measuring the switching time of the power device by controlling the on / off state of a second switching circuit and adjusting the output state of the operational amplifier circuit drive power supply; when performing an avalanche breakdown test, controlling the first switching circuit to be turned on and the second switching circuit to be disconnected, and causing the power device to undergo avalanche breakdown by adjusting the output state of the operational amplifier circuit drive power supply.

[0019] The testing method provided by this invention can perform both switching time and avalanche breakdown tests using the same device by changing the on / off states of the first and second switching circuits, thereby reducing equipment investment costs and overall testing time.

[0020] In one optional implementation, the method for testing switching time includes: controlling the first switching circuit and the second switching circuit to disconnect, controlling the power device to turn on, and simultaneously providing a test voltage from an external power supply; when the power inductor current reaches a first preset current value, controlling the power device to turn off and the second switching circuit to turn on; and after a first preset time, controlling the power device to turn on.

[0021] The testing method provided by this invention controls the on / off state and on / off timing of the switching circuit and power devices, and displays the switching time waveform on an oscilloscope.

[0022] In one optional embodiment, the avalanche breakdown test method includes: a first avalanche breakdown test method and a second avalanche breakdown test method, wherein the first avalanche breakdown test method includes: controlling a first switching circuit to be turned on and a second switching circuit to be turned off; after a second preset time, controlling a power device to be turned on, while an external power supply provides a test voltage; when the power inductor current reaches a first preset current value, controlling the power device to be turned off.

[0023] In one optional implementation, the second avalanche breakdown test method includes: controlling the first switching circuit to be turned on and the second switching circuit to be turned off, while an external power supply provides a test voltage; after a third preset time, controlling the power device to be turned on; and when the power inductor current reaches a first preset current value, controlling the power device to be turned off.

[0024] In one optional implementation, a clamping method is also included, which includes: adjusting the voltage across the power device by controlling the on / off states of the second single-pole single-throw relay, the third single-pole single-throw relay, and the fourth single-pole single-throw relay, adjusting the voltage of the external isolation power supply, and clamping the voltage across the power device to the avalanche breakdown voltage.

[0025] The testing method provided by this invention controls the on / off state of a single-pole single-throw relay and adjusts the voltage of an external isolation power supply to clamp the power device to the avalanche breakdown voltage, thereby preventing overvoltage breakdown and damage to the power device.

[0026] In one optional implementation, the clamping method includes: controlling the second and third single-pole single-throw relays to turn on and the fourth single-pole single-throw relay to turn off, thereby adjusting the voltage of the external isolation power supply; during the adjustment of the external isolation power supply voltage, when the avalanche breakdown voltage of the power device is greater than the sum of the external isolation power supply voltage and the threshold voltage of the power device, controlling the power device to turn on; during the adjustment of the external isolation power supply voltage, when the avalanche breakdown voltage of the power device is less than the sum of the external isolation power supply voltage and the threshold voltage of the power device, controlling the power device to turn off; during the adjustment of the external isolation power supply voltage, when the voltage across the power device rises to a first preset voltage value, controlling the power device to turn on; during the adjustment of the external isolation power supply voltage, when the avalanche breakdown voltage of the power device is equal to the sum of the external isolation power supply voltage and the threshold voltage of the power device, stopping the adjustment of the external isolation power supply voltage, thereby clamping the voltage across the power device to the sum of the current external isolation power supply voltage and the power device threshold voltage.

[0027] In one optional implementation, the clamping method includes: controlling the second single-pole single-throw relay and the fourth single-pole single-throw relay to be turned on and the third single-pole single-throw relay to be turned off, thereby adjusting the voltage of the external isolation power supply; during the adjustment of the voltage of the external isolation power supply, when the avalanche breakdown voltage of the power device is greater than the voltage of the external isolation power supply, controlling the power device to be turned on; during the adjustment of the voltage of the external isolation power supply, when the avalanche breakdown voltage of the power device is equal to the voltage of the external isolation power supply, stopping the adjustment of the voltage of the external isolation power supply, thereby clamping the voltage across the power device to the current voltage of the external isolation power supply. Attached Figure Description

[0028] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a composition diagram of a specific example of a power device characteristic testing circuit according to an embodiment of the present invention;

[0030] Figure 2 This is a specific circuit structure diagram of a power device characteristic testing circuit according to an embodiment of the present invention;

[0031] Figure 3 This is another specific circuit structure diagram of the power device characteristic testing circuit according to an embodiment of the present invention;

[0032] Figure 4This is a specific circuit structure diagram of the switching time test circuit according to an embodiment of the present invention;

[0033] Figure 5 This is a timing diagram of the switching time testing process according to an embodiment of the present invention;

[0034] Figure 6 , 7 These are all current flow diagrams during the switching time test process of embodiments of the present invention;

[0035] Figure 8 This is a specific circuit structure diagram of the avalanche breakdown test circuit according to an embodiment of the present invention;

[0036] Figure 9 This is a timing diagram of the avalanche breakdown test process according to an embodiment of the present invention;

[0037] Figure 10 This is another timing diagram of the avalanche breakdown test process according to an embodiment of the present invention;

[0038] Figure 11 , 12 These are all current flow diagrams during the avalanche breakdown test process in embodiments of the present invention;

[0039] Figure 13 This is a specific circuit structure diagram of the clamping circuit according to an embodiment of the present invention;

[0040] Figure 14 This is another specific circuit structure diagram of the clamping circuit in an embodiment of the present invention. Detailed Implementation

[0041] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0043] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0045] This invention provides a power device characteristic testing circuit that integrates an avalanche tester and a switching time tester. When customers need to measure both parameters of a power device simultaneously, it reduces equipment investment costs, initial setup time, and overall testing time. This invention can accelerate mass production product testing and reduce testing costs, paving the way for widespread application.

[0046] According to embodiments of the present invention, a power device characteristic testing circuit is provided, such as... Figure 1 As shown, it includes: a first switching circuit 1, a second switching circuit 2, a power inductor L, an adjustable gate drive resistor array 3, and an operational amplifier circuit 4.

[0047] like Figure 1 As shown, the first switching circuit 1 is connected in parallel with the external power supply; the second switching circuit 2 is connected in parallel with the power inductor L to form a first branch, the first end of the first branch is connected to the first end of the first switching circuit 1, and the second end of the first branch is connected to the first end of the power device DUT; the control terminal of the power device DUT is connected to the first end of the adjustable gate drive resistor array 3, and its second end and the second end of the first switching circuit 1 are both connected to the first ground terminal P_GND, and its second end is also connected to the second ground terminal VG_GND.

[0048] like Figure 1 As shown, the adjustable gate drive resistor array 3 has its second end connected to the output terminal of the operational amplifier circuit 4; the operational amplifier circuit 4 has its input terminal connected to the drive signal source VG, its first power supply terminal connected to the first drive power supply VG+, and its second power supply terminal connected to the second drive power supply VG-; both the first drive power supply VG+ and the second drive power supply VG- are connected to the second ground terminal VG_GND.

[0049] like Figure 1As shown, when performing a switching time test, the first switching circuit 1 is turned off, and the on / off state of the second switching circuit 2 is controlled to adjust the output state of the operational amplifier circuit 4 and the drive power supply, thereby measuring the switching time of the power device DUT.

[0050] Specifically, when performing switching time testing on the power device DUT, the first switching circuit 1 is opened, and the on / off state of the second switching circuit 2 is controlled at different times. The on / off state of the power device DUT is controlled by controlling the output state of the drive power supply at different times, and the switching time of the power device DUT is measured. The specific operation procedure for the switching time test is a mature existing test procedure, and will not be described in detail here.

[0051] Figure 1 In the process of performing an avalanche breakdown test, the first switch circuit 1 is turned on and the second switch circuit 2 is turned off. The output state of the signal source VG is adjusted by the operational amplifier circuit 4 to cause the power device DUT to undergo avalanche breakdown.

[0052] Specifically, when performing an avalanche breakdown test on a power device DUT, the first switching circuit 1 is turned on and the second switching circuit 2 is turned off, so that the power device DUT is connected in series with the power inductor L. The on / off state of the power device DUT is controlled by controlling the output state of the drive signal source VG at different times, and the avalanche breakdown parameters of the power device DUT are measured. The specific operation procedure of the avalanche breakdown test is a mature existing test procedure, and will not be described in detail here.

[0053] In some alternative implementations, such as Figure 2 As shown, the first switching circuit 1 includes a first single-pole single-throw relay K1 and a first diode D1. The cathode of the first diode D1 is connected to the first terminal of the second switching circuit 2 (i.e., S2) and the first terminal of the external power supply through the first single-pole single-throw relay K1, and its anode is connected to the second terminal of the power device DUT. The anode, the second terminal of the power device DUT, and the external power supply are all connected to the second ground terminal VG_GND.

[0054] Specifically, when performing a switching time test, the first single-pole single-throw relay K1 is controlled to open; when performing an avalanche breakdown test, the first single-pole single-throw relay K1 is controlled to close, forming a freewheeling circuit for the power inductor.

[0055] In some alternative implementations, such as Figure 2 As shown, the second switching circuit includes 2: a first controllable switch S2, whose first end is connected to the first end of the first switching circuit 1 and the external power supply, and whose second end is connected to the first end of the power device DUT, for freewheeling current to the power inductor L.

[0056] Optionally, the first controllable switch S2 is an IGBT without a body diode, which serves as a freewheeling current for the power inductor L.

[0057] In some alternative implementations, such as Figure 2 As shown, the adjustable gate drive resistor array 3 includes a first resistor array branch and a second resistor array branch connected in reverse parallel.

[0058] Optionally, such as Figure 2 As shown, the first resistor array branch includes a fourth diode D4 and a first adjustable resistor circuit R_P, with the anode of the fourth diode connected to the output terminal of the operational amplifier circuit 4; the second resistor array branch includes a fifth diode D5 and a second adjustable resistor circuit R_N, with the cathode of the fifth diode connected to the output terminal of the operational amplifier circuit 4.

[0059] In some alternative implementations, such as Figure 2 As shown, it also includes a power supply module 5, which includes a support capacitor C, a second controllable switch S1, and a programmable power supply HV_POWER. The first end of the support capacitor C is connected to the first end of the second controllable switch S1, and the second end of the support capacitor C is connected to the second end of the first switch circuit 1 (i.e., the series branch of K1 and D1) and the first ground terminal P_GND. The second controllable switch S1 has two ends connected to the first end of the first branch. The programmable power supply HV_POWER is connected in parallel with the support capacitor C and is used to provide test voltage for the power device DUT.

[0060] Specifically, when performing a switching time test, the second controllable switch S1 is turned on, and the programmable power supply HV_POWER and the supporting capacitor C together provide the test voltage for the power device DUT; when performing an avalanche test, the timing of the test voltage is controlled by controlling the turn-on timing of the second controllable switch S1 and the power device DUT, and the avalanche breakdown parameters of the power device DUT are measured.

[0061] In some alternative implementations, such as Figure 3 As shown, it also includes: a clamping circuit 6, whose power supply terminal is connected to an external isolation power supply VCLAMP, whose first terminal is connected to the second terminal of the first branch (i.e., the parallel branch of S2 and power inductor L), whose second terminal is connected to the control terminal of the power device DUT, and whose third terminal is connected to the second ground terminal VG_GND, used to absorb excess current in the circuit and clamp the voltage across the power device DUT to the avalanche breakdown voltage during the avalanche breakdown test.

[0062] Specifically, the voltage across the power device DUT can be adjusted by regulating the voltage of the external isolation power supply VCLAMP. When the voltage across the power device DUT is equal to the avalanche breakdown voltage, the voltage of the external isolation power supply VCLAMP is fixed at the current voltage value, clamping the voltage across the power device DUT to the avalanche breakdown voltage. When the voltage across the power device DUT is greater than the avalanche breakdown voltage, the clamping circuit 6 absorbs excess current in the circuit to prevent the power device DUT from avalanche breakdown.

[0063] In some alternative implementations, such as Figure 3 As shown, the clamping circuit 6 includes: a second single-pole single-throw relay K2, a third single-pole single-throw relay K3, a fourth single-pole single-throw relay K4, a second diode D2, and a third diode D3. The cathode of the second diode D2 is connected to the positive terminal of the external isolation power supply VCLAMP, and its anode is connected to the first terminal of the power device DUT through the second single-pole single-throw relay K2. The anode of the third diode D3 is connected to the negative terminal of the external isolation power supply VCLAMP, and its cathode is connected to the control terminal of the power device DUT through the third single-pole single-throw relay K3. Its cathode is also connected to the second ground terminal VG_GND through the fourth single-pole single-throw relay K4.

[0064] Specifically, the second diode D2 and the third diode D3 are used to prevent reverse power supply VCLAMP from damaging the power device DUT.

[0065] This invention provides a method for testing the characteristics of power devices. This method is applied to the above embodiments and their optional implementations. The method includes:

[0066] (1) When performing a switching time test, the first switching circuit is controlled to be disconnected, and the switching time of the power device is measured by controlling the on / off state of the second switching circuit and adjusting the output state of the operational amplifier circuit drive power supply.

[0067] (2) When performing an avalanche breakdown test, the first switch circuit is turned on and the second switch circuit is turned off, and the output state of the power supply driven by the operational amplifier circuit is adjusted to cause the power device to avalanche breakdown.

[0068] In some alternative implementations, the method for testing the switching time includes:

[0069] The first and second switching circuits are disconnected, the power device is turned on, and the external power supply provides the test voltage. When the power inductor current reaches the first preset current value, the power device is turned off and the second switching circuit is turned on. After the first preset time, the power device is turned on again.

[0070] Specifically, when testing the switching time parameters of the power device DUT, the first single-pole single-throw relay K1 to the fourth single-pole single-throw relay K4 are released, and the switching time measurement circuit is as follows: Figure 4 As shown.

[0071] Figure 4 In this circuit, the programmable power supply HV_POWER and capacitor C provide VDS voltage to the power device DUT; the power inductor L acts as a series inductor load of the power device DUT to slow down the rise rate of the IDS current; the first controllable switch S2 provides freewheeling current to the power inductor L through timing control; the adjustable gate drive resistor array (R_P, R_N) controls the turn-on and turn-off speed of the power device DUT; the I_Sense current sensor is used to detect the real-time value of IDS; VGS, VDS, and IDS are respectively connected to the measurement channels of an oscilloscope to measure the corresponding switching time waveforms.

[0072] The measurement timing diagram for the switching time test is as follows: Figure 5 As shown, in state II, the drive signal source VG controls the power device DUT to be in the on state. At this time, the high-current circuit operates according to... Figure 6 The dashed line indicates that the current rises at a slower rate due to the presence of the power inductor L.

[0073] like Figure 5 As shown, when the I_Sense current sensor detects that the IDS current reaches the set value Iset through the subsequent detection circuit, the drive signal source VG controls the power device DUT to turn off, reaching state III. At this time, the first controllable switch S2 is turned on, providing freewheeling for the power inductor L, and the current loop proceeds according to... Figure 7 The dashed line indicates flow. The first controllable switch S2 acts as a freewheeling diode for the power inductor L.

[0074] like Figure 5 As shown, in state IV, the drive signal source VG controls the power device DUT to re-enter the conduction state, and the current loop reference at this time... Figure 6 The waveforms of VGS, VDS, and IDS are sampled by the oscilloscope, processed by the host computer, and the test results of the switching time parameters, such as TDON, TR, TDOFF, TF, EON, EOFF, etc., will not be elaborated here.

[0075] In some alternative implementations, the avalanche breakdown test method includes: a first avalanche breakdown test method and a second avalanche breakdown test method.

[0076] Specifically, (1) when the driving signal source VG turns on the power device DUT, the second controllable switch S1 simultaneously provides VDD voltage. The avalanche breakdown test method under this switching timing is the first avalanche breakdown test method; (2) for a period of time before the driving signal source VG turns on the power device DUT, the second controllable switch S1 is controlled to output VDD voltage in advance. The avalanche breakdown test method under this switching timing is the second avalanche breakdown test method.

[0077] Specifically, when testing the avalanche breakdown parameters of the power device DUT, the first single-pole single-throw relay K1 is closed, the second single-pole single-throw relays K2 to K4 are released, the first controllable switch S2 is turned off, and the avalanche breakdown measurement circuit is as follows: Figure 8 As shown. The programmable power supply HV_POWER and capacitor C provide the IDS current; the power inductor L acts as a series inductor load in the current loop, controlling the rise rate of the IDS; the adjustable gate drive resistor array (R_P, R_N) controls the turn-on and turn-off speed of the power device DUT, used to control the di / dt current rise rate parameter during measurement; the I_Sense current sensor detects the real-time value of the IDS; VGS, VDS, and IDS are respectively connected to the oscilloscope measurement channels to measure the corresponding switching time waveforms.

[0078] Specifically, a square wave drive signal source VG is used to excite the power device DUT, which is already supplied with a power supply voltage VDD. When ID reaches a set value, the first drive power supply VG+ is switched to the second drive power supply VG-. The power inductor current cannot change abruptly, resulting in a high voltage BVDSS on the drain terminal of the power device DUT, which will break down the power device DUT, causing avalanche breakdown.

[0079] In some alternative implementations, the first avalanche breakdown test method includes:

[0080] The system controls the first switching circuit to be turned on and the second switching circuit to be turned off; after a second preset time, the system controls the power device to be turned on, and at the same time, the external power supply provides the test voltage; when the power inductor current reaches the first preset current value, the system controls the power device to be turned off.

[0081] The measurement timing diagram for the first avalanche breakdown test is as follows: Figure 9 As shown, in state II, the drive signal source VG controls the power device DUT to be in the on state, at which time the high current loop operates according to... Figure 11 The dashed line indicates that the current is flowing linearly and gradually increases due to the presence of the power inductor L.

[0082] like Figure 9As shown, when the I_Sense current sensor detects that the IDS current reaches the set value Iset through the subsequent detection loop, the drive signal source VG controls the power device DUT to turn off, reaching state III, and the current loop proceeds according to... Figure 12 The dashed line represents the flow. Since the power inductor current cannot change abruptly, a high voltage BVDSS is generated across the drain (D) terminal of the power device under test (DUT), which will cause the DUT to break down, resulting in avalanche breakdown. The first diode D1 serves as a shoot-through after the power device DUT breaks down and a freewheeling current for the power inductor L. The waveforms of VGS, VDS, and IDS are sampled by an oscilloscope, processed by a host computer, and the test results of the avalanche test parameters are output; these will not be elaborated further here.

[0083] In some optional implementations, the second avalanche breakdown test method includes: controlling the first switching circuit to be turned on and the second switching circuit to be turned off, while an external power supply provides a test voltage; after a third preset time, controlling the power device to be turned on; and when the power inductor current reaches a first preset current value, controlling the power device to be turned off.

[0084] The measurement timing diagram for the second avalanche breakdown test is as follows: Figure 10 As shown.

[0085] It should be noted that the second avalanche breakdown test method can be selected according to different testing needs of customers, and will not be elaborated here.

[0086] In some alternative implementations, a clamping method is also included to... Figure 3 For example, the clamping method includes: adjusting the voltage across the power device DUT by controlling the on / off state of the second single-pole single-throw relay K2, the third single-pole single-throw relay K3, and the fourth single-pole single-throw relay K4, adjusting the voltage of the external isolation power supply VCLAMP, and clamping the voltage across the power device DUT to the avalanche breakdown voltage.

[0087] In some alternative implementations, with Figure 3 For example, clamping methods include:

[0088] Control the second single-pole single-throw relay K2 and the third single-pole single-throw relay K3 to be turned on, and the fourth single-pole single-throw relay K4 to be turned off, thereby adjusting the voltage of the external isolation power supply VCLAMP.

[0089] like Figure 13 As shown, during the process of adjusting the voltage of the external isolation power supply VCLAMP, when the avalanche breakdown voltage of the power device DUT is greater than the sum of the voltage of the external isolation power supply VCLAMP and the threshold voltage of the power device DUT, the power device DUT is controlled to turn on.

[0090] Specifically, when the avalanche breakdown voltage BVDSS is greater than the sum of the voltage of the isolated power supply VCLAMP and the threshold voltage VTH of the power device DUT, that is, when BVDSS>VCLAMP+VTH, the power device DUT is turned on, and the voltage across the power device DUT drops at this time.

[0091] As Figure 13 illustrated, during the process of adjusting the voltage of the external isolated power supply VCLAMP, when the avalanche breakdown voltage of the power device DUT is less than the sum of the voltage of the external isolated power supply VCLAMP and the threshold voltage of the power device DUT, the power device DUT is controlled to turn off.

[0092] Specifically, when BVDSS<VCLAMP+VTH, the power device DUT is controlled to turn off.

[0093] As Figure 13 illustrated, during the process of adjusting the voltage of the external isolated power supply VCLAMP, when the voltage across the power device DUT rises to a first preset voltage value, the power device DUT is controlled to turn on.

[0094] Specifically, after the power device DUT is controlled to turn off, when the voltage across the power device DUT rises to the first preset voltage value, the power device DUT is controlled to continue conducting, and the second diode D2 and the third diode D3 absorb excess current in the circuit.

[0095] As Figure 13 illustrated, during the process of adjusting the voltage of the external isolated power supply VCLAMP, when the avalanche breakdown voltage of the power device DUT is equal to the sum of the voltage of the external isolated power supply VCLAMP and the threshold voltage of the power device DUT, the adjustment of the voltage of the external isolated power supply VCLAMP is stopped, so that the voltage across the power device DUT is clamped to the sum of the voltage of the current external isolated power supply VCLAMP and the threshold voltage of the power device DUT.

[0096] Specifically, when BVDSS=VCLAMP+VTH, the adjustment of the voltage of the external isolated power supply VCLAMP is stopped, and at this time the voltage across the power device DUT is clamped to VCLAMP+VTH, preventing the power device DUT from being damaged due to avalanche breakdown.

[0097] In some alternative embodiments, taking Figure 3 as an example, the voltage clamping method includes:

[0098] controlling the second single-pole single-throw relay K2 and the fourth single-pole single-throw relay K4 to conduct, controlling the third single-pole single-throw relay K3 to open, and adjusting the voltage of the external isolated power supply VCLAMP.

[0099] As Figure 14As shown, during the process of adjusting the voltage of the external isolation power supply VCLAMP, when the avalanche breakdown voltage of the power device DUT is greater than the voltage of the external isolation power supply VCLAMP, the power device DUT is controlled to turn on.

[0100] Specifically, when the avalanche breakdown voltage BVDSS is greater than the voltage of the external isolation power supply VCLAMP, i.e., BVDSS>VCLAMP, the second diode D2 and the third diode D3 absorb the excess current in the circuit.

[0101] like Figure 14 As shown, during the process of adjusting the voltage of the external isolation power supply VCLAMP, when the avalanche breakdown voltage of the power device DUT is equal to the voltage of the external isolation power supply VCLAMP, the adjustment of the voltage of the external isolation power supply VCLAMP is stopped, so that the voltage across the power device DUT is clamped to the current voltage of the external isolation power supply VCLAMP.

[0102] Specifically, when the avalanche breakdown voltage BVDSS is equal to the voltage of the external isolation power supply VCLAMP, i.e., BVDSS>VCLAMP, the adjustment of the voltage of the external isolation power supply VCLAMP is stopped. At this time, the voltage across the power device DUT is clamped to VCLAMP to prevent the power device DUT from being damaged by avalanche breakdown.

[0103] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A power device characteristic testing circuit, characterized in that, include: The circuit comprises a first switching circuit, a second switching circuit, a power inductor, an adjustable gate drive resistor array, and an operational amplifier circuit. The first switching circuit is connected in parallel with the external power supply; The second switching circuit is connected in parallel with the power inductor to form the first branch; the first end of the first branch is connected to the first end of the first switching circuit, and the second end of the first branch is connected to the first end of the power device. The power device has its control terminal connected to the first terminal of the adjustable gate drive resistor array, its second terminal and the second terminal of the first switching circuit are both connected to the first ground terminal, and its second terminal is also connected to the second ground terminal. An adjustable gate drive resistor array, the second end of which is connected to the output terminal of the operational amplifier circuit; The operational amplifier circuit has its input terminal connected to a drive signal source, its first power supply terminal connected to a first drive power supply, and its second power supply terminal connected to a second drive power supply; both the first drive power supply and the second drive power supply are connected to the second ground terminal. When performing a switching time test, the first switching circuit is turned off, and the output state of the operational amplifier circuit driving the signal source is adjusted by controlling the on / off state of the second switching circuit, and the switching time of the power device is measured. When performing an avalanche breakdown test, the first switching circuit is turned on and the second switching circuit is turned off, and the output state of the signal source driven by the operational amplifier circuit is adjusted to cause the power device to undergo avalanche breakdown. The power device characteristic test circuit also includes: The clamping circuit has its power supply terminal connected to an external isolated power supply, its first terminal connected to the second terminal of the first branch, its second terminal connected to the control terminal of the power device, and its third terminal connected to the second ground terminal. It is used to absorb excess current in the circuit and clamp the voltage across the power device to the avalanche breakdown voltage during the avalanche breakdown test. The clamping circuit includes: a second single-pole single-throw relay, a third single-pole single-throw relay, a fourth single-pole single-throw relay, a second diode, and a third diode, wherein... The second diode has its cathode connected to the positive terminal of the external isolation power supply, and its anode connected to the first terminal of the power device through the second single-pole single-throw relay. The third diode has its anode connected to the negative terminal of the external isolation power supply, its cathode connected to the control terminal of the power device through the third single-pole single-throw relay, and its cathode also connected to the second ground terminal through the fourth single-pole single-throw relay. The clamping circuit can selectively clamp the voltage across the power device to the voltage of the isolation power supply, or to the sum of the voltage of the isolation power supply and the threshold voltage of the power device, by controlling the on / off combination of the second single-pole single-throw relay, the third single-pole single-throw relay, and the fourth single-pole single-throw relay.

2. The test circuit according to claim 1, characterized in that, The first switching circuit includes a first single-pole single-throw relay and a first diode, wherein, The cathode of the first diode is connected to the first terminal of the second switching circuit and the first terminal of the external power supply through the first single-pole single-throw relay, and its anode is connected to the second terminal of the power device. The anode, the second terminal of the power device, and the second terminal of the external power supply are all connected to the second ground terminal.

3. The test circuit according to claim 1, characterized in that, The second switching circuit includes: A first controllable switch has its first terminal connected to the first terminal of the first switching circuit and an external power supply, and its second terminal connected to the first terminal of the power device, for providing freewheeling current to the power inductor.

4. The test circuit 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.

5. The test circuit according to claim 1, characterized in that, It also includes a power module, which comprises: a support capacitor, a second controllable switch, and a programmable power supply, wherein... A supporting capacitor, the first end of which is connected to the first end of the second controllable switch, and the second end of which is connected to the second end of the first switch circuit and the first grounding end; The second controllable switch has its two ends connected to the first end of the first branch; A programmable power supply, connected in parallel with the supporting capacitor, is used to provide a test voltage for the power device.

6. A method for testing the characteristics of power devices, characterized in that, The power device characteristic testing circuit applied to any one of claims 1 to 5, the testing method comprising: When performing a switching time test, the first switching circuit is controlled to be disconnected, and the switching time of the power device is measured by controlling the on / off state of the second switching circuit and adjusting the output state of the operational amplifier circuit drive power supply. During an avalanche breakdown test, the first switching circuit is turned on and the second switching circuit is turned off. The output state of the power supply is adjusted by the operational amplifier circuit to cause the power device to undergo avalanche breakdown.

7. The test method according to claim 6, characterized in that, The method for testing the switching time includes: The first and second switching circuits are disconnected, the power device is turned on, and the external power supply provides the test voltage. When the power inductor current reaches the first preset current value, the control power device is turned off and the second switching circuit is turned on. After the first preset time, the control power device is turned on.

8. The test method according to claim 6, characterized in that, The avalanche breakdown test method includes: a first avalanche breakdown test method and a second avalanche breakdown test method, wherein the first avalanche breakdown test method includes: The first switching circuit is turned on, and the second switching circuit is turned off. After the second preset time, the control power device is turned on, and at the same time the external power supply provides the test voltage. When the power inductor current reaches the first preset current value, the power device is turned off.

9. The test method according to claim 8, characterized in that, The second avalanche breakdown test method includes: The first switch circuit is turned on, the second switch circuit is turned off, and the external power supply provides the test voltage. After the third preset time, the control power device is turned on; When the power inductor current reaches the first preset current value, the power device is turned off.

Images