MOSFET and diode avalanche test system and method

Abstract

The invention discloses an avalanche test system and method for an MOSFET and a diode, and the system enables a sampling module, a signal conditioning module, an analog-digital conversion module, a digital control core module, an isolation drive module and an upper computer to be integrated on a test board, and achieves the avalanche test of the MOSFET and the diode. Accurate acquisition of voltage signals of a fast rising edge and a fast falling edge is realized by using a resistance-capacitance voltage division network in the sampling module; sampling current and voltage are processed through the signal conditioning module, negative current collection is achieved, and the data accuracy is improved; compared with a method for controlling the maximum avalanche current in a loop by controlling the conduction time of the MOSFET in the prior art, the method has the advantages that the current signal is analyzed in real time, and the MOSFET is controlled to be turned off when the avalanche current reaches the preset current value by monitoring the current signal in real time, so that the acquired avalanche current is more accurate, and the reliability of the avalanche current is improved. And meanwhile, the efficiency is also improved.

Description

Technical Field

[0001] The invention belongs to the field of power electronics, and in particular relates to a MOSFET and a diode avalanche test system and method. Background Art

[0002] With the development of electronic technology, high-voltage devices are widely used in the field of power electronics, and their reliability issues are also prominent. For devices in inductive loads, when the switch tube is turned off, the inductor current cannot change suddenly, causing it to generate a large reverse electromotive force, causing the device to enter an avalanche state, which can cause irreversible damage to the device in severe cases. Therefore, it is very necessary to provide a test platform for avalanche testing for the device to analyze the avalanche reliability of the device.

[0003] The current avalanche test is mainly for two devices, MOSFET (Metal-Oxide-Semiconductor Field-EffectTransistor) and diode. For MOSFET, the avalanche test circuit includes power supply, inductor, and MOSFET. The MOSFET itself is used as a switch tube. When the MOSFET is turned on, the inductor is charged. When the MOSFET is turned off, the inductor causes the MOSFET to enter an avalanche state. For the diode, a switch tube and the diode under test itself (the avalanche voltage of the MOSFET is higher than that of the diode under test) are required in the loop. The two are connected in parallel. When the MOSFET is turned on, the power supply charges the inductor through the inductor-MOSFET-ground loop. Then the MOSFET is turned off. The reverse electromotive force of the inductor causes the diode to avalanche, and current flows through the diode.

[0004] The existing avalanche test platform is generally for MOSFET, and there are few test platforms for diodes. There is no test platform that is compatible with both, resulting in a waste of resources; the current test generally uses more measuring equipment and oscilloscopes, which are costly, large in size, and inconvenient for testing. The current avalanche test system is not highly intelligent, and uses pulse time to charge the inductor, which cannot achieve precise control of the current; the voltage acquisition of the current avalanche test system uses a resistor network for voltage division, and does not consider the voltage division at high frequency, and the avalanche voltage acquisition with a steep rising edge is not accurate enough (rising edge or overshoot occurs); and during the acquisition of the avalanche current, the current will be reversed at the end of the avalanche, and the existing test system cannot detect the reverse current; the current avalanche test system indirectly controls the avalanche current by controlling the time of charging the inductor in the loop, but the parasitic parameters in the loop and the device are unknown, and the actual current will deviate from the expected current. To reach a certain value, it is necessary to adjust the charging time multiple times, which is inconvenient. In summary, the existing avalanche test platform has the problems of not being able to achieve precise control of the current, not being accurate enough in testing accuracy, high design cost, and not being able to achieve test compatibility with MOSFET and diodes. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a MOSFET and diode avalanche test system and method. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides an avalanche test system for MOSFET and diode, comprising:

[0007] Sampling module, signal conditioning module, analog-to-digital conversion module, digital control core module, isolation drive module and host computer; among them,

[0008] The sampling module is used to sample the current and voltage corresponding to the MOSFET or diode to be tested respectively by using its own sampling resistor and resistor-capacitor voltage divider network to obtain the sampled current and sampled voltage;

[0009] The signal conditioning module is used to condition the sampled current and sampled voltage respectively using its own current operational amplifier conditioning circuit and voltage operational amplifier conditioning circuit to obtain a conditioned current signal and a conditioned voltage signal;

[0010] The analog-to-digital conversion module is used to convert the conditioned current signal into a current digital signal, and convert the conditioned voltage signal into a voltage digital signal;

[0011] The digital control core module is used to control the isolation drive module according to a preset current value to turn on or off the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested; to charge the inductor in the sampling module; to store the received current digital signal and voltage digital signal, and transmit them to the host computer;

[0012] The host computer is used to set preset parameters; perform integral calculation on avalanche tolerance according to the received current digital signal, voltage digital signal and preset parameters to obtain avalanche test results; the preset parameters include preset current values.

[0013] In one embodiment of the present invention, the sampling module includes:

[0014] Sampling resistor R01, sampling resistor R02, resistor-capacitor voltage divider network, voltage source, inductor, base corresponding to the MOSFET to be tested and base corresponding to the diode to be tested; wherein,

[0015] The first end of the sampling resistor R01 is connected to the source of the base corresponding to the MOSFET to be tested, and the second end is grounded;

[0016] The first end of the sampling resistor R02 is connected to the positive electrode of the base corresponding to the diode to be tested, and the second end is connected to the second end of the sampling resistor R01;

[0017] The first end of the RC voltage divider network is respectively connected to the cathode of the base corresponding to the diode to be tested and the drain of the base corresponding to the MOSFET to be tested, and the second end is connected to the second end of the sampling resistor R02;

[0018] The positive terminal of the voltage source is connected to the first end of the inductor, and the negative terminal is connected to the second end of the sampling resistor R01;

[0019] The second end of the inductor is connected to the drain of the base corresponding to the MOSFET to be tested.

[0020] In one embodiment of the present invention, a resistor-capacitor voltage divider network includes:

[0021] Resistor R03, resistor R04, capacitor C01 and capacitor C02; wherein,

[0022] The first end of the resistor R03 is connected to the first end of the capacitor C01, serving as the first end of the resistor-capacitor voltage divider network, and the second end is connected to the second end of the capacitor C01;

[0023] The first end of the resistor R04 is connected to the second end of the resistor R03, and the second end is connected to the second end of the capacitor C02, serving as the second end of the resistor-capacitor voltage divider network;

[0024] The first end of the capacitor C02 is connected to the second end of the capacitor C01.

[0025] In one embodiment of the present invention, in the RC voltage divider network, the values ​​of the resistor R03, the resistor R04, the capacitor C01 and the capacitor C02 satisfy:

[0026]

[0027] Among them, R 03 Indicates the resistance value of resistor R03, R 04 Indicates the resistance value of resistor R04, C 01 Indicates the capacitance value of capacitor C01, C 02 Represents the capacitance value of capacitor C02.

[0028] In one embodiment of the present invention, when the diode to be tested is subjected to an avalanche test, a MOSFET connected in parallel with the diode to be tested is arranged at a position corresponding to the MOSFET to be tested.

[0029] In one embodiment of the present invention, a current operational amplifier conditioning circuit includes:

[0030] A differential ratio amplification module, a level raising module and a first filter follower module; wherein,

[0031] The differential ratio amplification module comprises:

[0032] Resistor R1, resistor R2, resistor R3, resistor R4 and operational amplifier A1; wherein,

[0033] The first end of the resistor R1 is grounded, and the second end is connected to the inverting input terminal of the operational amplifier A1;

[0034] The first end of the resistor R2 is connected to the second end of the resistor R1, and the second end is connected to the output end of the operational amplifier A1;

[0035] The first end of the resistor R3 is connected to the sampling current, and the second end is connected to the non-inverting input end of the operational amplifier A1;

[0036] The first end of the resistor R4 is connected to the second end of the resistor R3, and the second end is grounded;

[0037] The level raising module comprises:

[0038] Resistor R5, resistor R7, resistor R8, resistor R9 and operational amplifier A2; wherein,

[0039] A 0.5V voltage signal is input to the first end of the resistor R5, and a second end is connected to the non-inverting input end of the operational amplifier A2;

[0040] The first end of the resistor R7 is connected to the output end of the operational amplifier A1, and the second end is connected to the non-inverting input end of the operational amplifier A2;

[0041] The first end of the resistor R8 is grounded, and the second end is connected to the inverting input terminal of the operational amplifier A2;

[0042] The first end of the resistor R9 is connected to the inverting input terminal of the operational amplifier A2, and the second end is connected to the output terminal of the operational amplifier A2;

[0043] The first filter follower module comprises:

[0044] Resistor R10, capacitor C1 and voltage follower A3; wherein,

[0045] The first end of the resistor R10 is connected to the output end of the operational amplifier A2, and the second end is connected to the in-phase input end of the voltage follower A3;

[0046] The first end of the capacitor C1 is connected to the second end of the resistor R10, and the second end is grounded;

[0047] The inverting input terminal of the voltage follower A3 is connected to its own output terminal.

[0048] In one embodiment of the present invention, a voltage operational amplifier conditioning circuit includes:

[0049] A voltage follower module, an addition module and a second filter follower module; wherein,

[0050] The voltage follower module comprises:

[0051] Resistor R11 and operational amplifier A4; where,

[0052] The first end of the resistor R11 is connected to the sampling voltage, and the second end is connected to the non-inverting input end of the operational amplifier A4;

[0053] The inverting input terminal of the operational amplifier A4 is connected to its own output terminal;

[0054] The addition module comprises:

[0055] Resistor R12, resistor R13, resistor R14, resistor R15 and operational amplifier A5; wherein,

[0056] A 0.5V voltage signal is input to the first end of the resistor R12, and a second end is connected to the non-inverting input end of the operational amplifier A5;

[0057] The first end of the resistor R13 is connected to the output end of the operational amplifier A4, and the second end is connected to the non-inverting input end of the operational amplifier A5;

[0058] The first end of the resistor R14 is grounded, and the second end is connected to the inverting input terminal of the operational amplifier A5;

[0059] The first end of the resistor R15 is connected to the inverting input end of the operational amplifier A5, and the second end is connected to the output end of the operational amplifier A5;

[0060] The second filter follower module comprises:

[0061] Resistor R16, capacitor C2 and voltage follower A6; wherein,

[0062] The first end of the resistor R16 is connected to the output end of the operational amplifier A5, and the second end is connected to the non-inverting input end of the voltage follower A6;

[0063] The first end of the capacitor C2 is connected to the second end of the resistor R16, and the second end is grounded;

[0064] The inverting input terminal of the voltage follower A6 is connected to its own output terminal.

[0065] In one embodiment of the present invention, the digital control core module controls the isolation driving module according to a preset current value to turn on or off the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested, including:

[0066] After the digital control core module obtains the preset current value, it controls the isolation drive module to turn on the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested; when the current digital signal reaches the preset current value, it controls the isolation drive module to turn off the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested.

[0067] In a second aspect, the present invention provides an avalanche test method for MOSFET and diode, which is applied to the avalanche test system as described in the first aspect, and the method comprises:

[0068] S1, using a host computer to set preset parameters; the preset parameters include preset current values;

[0069] S2, using the digital control core module to control the isolation drive module to turn on the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested;

[0070] S3, using the sampling module to sample the current and voltage corresponding to the MOSFET or the diode to be tested, to obtain the sampled current and the sampled voltage;

[0071] S4, using a signal conditioning module to condition the sampled current and the sampled voltage respectively to obtain a conditioned current signal and a conditioned voltage signal, and using an analog-to-digital conversion module to convert the conditioned current signal into a current digital signal and convert the conditioned voltage signal into a voltage digital signal;

[0072] S5, using the digital control core module to store the received current digital signal and voltage digital signal, when the current digital signal reaches the preset current value, control the isolation drive module to turn off the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested, start the avalanche test, and send the current digital signal and voltage digital signal to the host computer;

[0073] S6, using the host computer to integrate the avalanche tolerance according to the received current digital signal, voltage digital signal and preset parameters to obtain the avalanche test result; judging the number of current avalanche tests, if the number of current avalanche tests is less than the number of avalanche tests in the preset parameters, return to S2 to continue testing; if the number of current avalanche tests is equal to the number of avalanche tests in the preset parameters, the avalanche test ends.

[0074] In one embodiment of the present invention, the preset parameters further include:

[0075] The current peak value when the inductor in the sampling module is charged, the inductance value of the inductor in the sampling module, and the power supply voltage.

[0076] Beneficial effects of the present invention:

[0077] In the solution provided by the present invention, a sampling module, a signal conditioning module, an analog-to-digital conversion module, a digital control core module, an isolation drive module and a host computer can be integrated on a test board to realize avalanche testing of MOSFET and diode, thereby solving the problem that MOSFET and diode cannot be tested compatible in the prior art and reducing the design cost; the resistor-capacitor voltage divider network in the sampling module is used to realize accurate collection of voltage signals at fast rising and falling edges; the sampling current and the sampling voltage are processed by the signal conditioning module to realize the collection of negative current signals, thereby greatly improving the accuracy of test data; compared with the method of controlling the conduction time of MOSFET to control the maximum avalanche current in the loop, which is mostly used in the prior art, the present invention adopts a method of real-time analysis of the current signal, and through real-time monitoring of the current signal, when the avalanche current reaches a preset current value, the MOSFET is controlled to be turned off, thereby making the acquired avalanche current more accurate and also improving the efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Figure 1 A schematic diagram of the principle of a MOSFET and diode avalanche test system provided by an embodiment of the present invention;

[0079] Figure 2 A schematic diagram of the structure of a sampling circuit in an avalanche test system for a MOSFET and a diode provided by an embodiment of the present invention;

[0080] Figure 3 A schematic diagram of the structure of a current amplifier conditioning circuit in a MOSFET and diode avalanche test system provided by an embodiment of the present invention;

[0081] Figure 4 A schematic diagram of the structure of a voltage amplifier conditioning circuit in a MOSFET and diode avalanche test system provided by an embodiment of the present invention;

[0082] Figure 5 A schematic diagram of the steps of a MOSFET and a diode avalanche test method provided by an embodiment of the present invention;

[0083] Figure 6 A schematic flow chart of a method for avalanche testing a MOSFET and a diode provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0084] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0085] There are two main test methods for avalanche testing at present. One is to implement avalanche testing with UIS circuit topology. Specifically, a signal generator is used to control the switch of MOSFET, and a voltage probe and a current probe are used to collect the current and voltage of the device avalanche, which are displayed through an oscilloscope. Then, the avalanche waveform is manually analyzed and processed. This method is costly, and the oscilloscope is large in size, which is not convenient for testing. The other is to connect a sampling resistor and a parallel voltage divider resistor in series in the UIS circuit, and use a current and voltage acquisition circuit to perform analog-to-digital conversion, and then collect, process and transmit the data by a digital chip, and display the waveform data through a host computer. This circuit can only implement avalanche testing of MOSFET, and the voltage and current accuracy is insufficient (reverse current cannot be detected, and the faster rising and falling edges of the voltage signal cannot be accurately captured). The current avalanche test charges the inductor by controlling the time when the MOSFET is turned on. The avalanche tolerance is calculated by collecting the maximum avalanche current using a formula, but the parasitic parameters in the circuit and the device are unknown, and the actual current will deviate from the expected current. To reach a certain value, the charging time needs to be adjusted multiple times, which is inconvenient.

[0086] In order to achieve the purpose of performing avalanche testing on both MOSFET and diode, an embodiment of the present invention provides a system and method for avalanche testing of MOSFET and diode.

[0087] Below, firstly, an avalanche test system for MOSFET and diode provided by an embodiment of the present invention is introduced.

[0088] An avalanche test system for MOSFET and diode provided by an embodiment of the present invention is as follows: Figure 1 As shown, this may include:

[0089] Sampling module, signal conditioning module, analog-to-digital conversion module, digital control core module, isolation drive module and host computer; among them,

[0090] The sampling module is used to sample the current and voltage corresponding to the MOSFET or diode to be tested respectively by using its own sampling resistor and resistor-capacitor voltage divider network to obtain the sampled current and sampled voltage;

[0091] The signal conditioning module is used to condition the sampled current and sampled voltage respectively using its own current operational amplifier conditioning circuit and voltage operational amplifier conditioning circuit to obtain a conditioned current signal and a conditioned voltage signal;

[0092] The analog-to-digital conversion module is used to convert the conditioned current signal into a current digital signal and to convert the conditioned voltage signal into a voltage digital signal;

[0093] The digital control core module is used to control the isolation drive module according to the preset current value to turn on or off the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested; to charge the inductor in the sampling module; to store the received current digital signal and voltage digital signal, and transmit them to the host computer;

[0094] The host computer is used to set preset parameters; perform integral calculation on the avalanche withstand capability according to the received current digital signal, voltage digital signal and preset parameters to obtain the avalanche test result; the preset parameters include preset current values.

[0095] In the solution provided by the embodiment of the present invention, the sampling module, signal conditioning module, analog-to-digital conversion module, digital control core module, isolation drive module and host computer can be integrated on a test board to realize avalanche testing of MOSFET and diode; the resistor-capacitor voltage divider network in the sampling module is used to realize accurate collection of voltage signals at fast rising and falling edges; the sampling current and sampling voltage are processed by the signal conditioning module to realize the collection of negative current signals, which greatly improves the accuracy of the data; compared with the method of controlling the conduction time of MOSFET to control the maximum avalanche current in the loop, which is mostly used in the prior art, the present invention adopts a method of real-time analysis of the current signal, and through real-time monitoring of the current signal, when the avalanche current reaches a preset current value, the MOSFET is controlled to be turned off, thereby making the acquired avalanche current more accurate and also improving the efficiency.

[0096] For ease of understanding, each module of the avalanche test system proposed in the embodiment of the present invention is introduced separately below.

[0097] Sampling Module

[0098] Sampling modules, such as Figure 2 As shown, this may include:

[0099] Sampling resistor R01, sampling resistor R02, resistor-capacitor voltage divider network, voltage source, inductor, base corresponding to the MOSFET to be tested and base corresponding to the diode to be tested; wherein,

[0100] The first end of the sampling resistor R01 is connected to the source of the base corresponding to the MOSFET to be tested, and the second end is grounded;

[0101] The first end of the sampling resistor R02 is connected to the positive electrode of the base corresponding to the diode to be tested, and the second end is connected to the second end of the sampling resistor R01;

[0102] The first end of the RC voltage divider network is respectively connected to the cathode of the base corresponding to the diode to be tested and the drain of the base corresponding to the MOSFET to be tested, and the second end is connected to the second end of the sampling resistor R02;

[0103] The positive terminal of the voltage source is connected to the first end of the inductor, and the negative terminal is connected to the second end of the sampling resistor R01;

[0104] The second end of the inductor is connected to the drain of the base corresponding to the MOSFET to be tested.

[0105] It can be understood that two bases can be selected and placed at positions corresponding to the MOSFET to be tested and the diode to be tested, respectively, to realize avalanche testing of the MOSFET to be tested and the diode to be tested. During the test, it is only necessary to place the MOSFET to be tested on the corresponding base (the base corresponding to the diode to be tested is equivalent to an open circuit) to realize the avalanche test of the MOSFET; when the avalanche test is performed on the diode to be tested, the MOSFET connected in parallel with the diode to be tested is set at the position corresponding to the MOSFET to be tested, and the diode to be tested is placed on the corresponding base to realize the avalanche test of the diode.

[0106] The sampling module can use its own sampling resistor and resistor-capacitor voltage divider network to sample the current and voltage corresponding to the MOSFET or diode to be tested, and obtain the sampled current and sampled voltage. Figure 2 As shown in , when current sampling is performed, the sampling resistor introduced in the loop can be used to detect the voltage across it to obtain current information. For the MOSFET to be tested, its current is obtained through the sampling resistor R01, which can be expressed as the corresponding sampling current I MOSFor the diode to be tested, its current is obtained through the sampling resistor R02, which can be expressed as the corresponding sampling current I DIODE The sampling voltages of both are obtained by the resistor-capacitor voltage divider network and can be expressed as V AV .

[0107] Specifically, the resistor-capacitor voltage divider network, such as Figure 2 As shown, this may include:

[0108] Resistor R03, resistor R04, capacitor C01 and capacitor C02; wherein,

[0109] The first end of the resistor R03 is connected to the first end of the capacitor C01 as the first end of the resistor-capacitor voltage divider network, and the second end is connected to the second end of the capacitor C01;

[0110] The first end of the resistor R04 is connected to the second end of the resistor R03, and the second end is connected to the second end of the capacitor C02, serving as the second end of the resistor-capacitor voltage divider network;

[0111] A first end of the capacitor C02 is connected to a second end of the capacitor C01 .

[0112] When sampling voltage, it can be realized by using a parallel resistor-capacitor voltage divider network. At low frequencies, the reactance of the resistor is much smaller than that of the capacitor, so the voltage divider is determined by the resistor. At high frequencies, the reactance of the resistor is much larger than that of the capacitor, so the voltage divider is determined by the capacitor. Therefore, in order to make the waveform acquisition accurate, it is necessary to specially design the specifications of each device in the resistor-capacitor voltage divider network. The specific design is as follows:

[0113] In the resistor-capacitor voltage divider network, the values ​​of resistor R03, resistor R04, capacitor C01 and capacitor C02 satisfy:

[0114]

[0115] Among them, R 03 Indicates the resistance value of resistor R03, R 04 Indicates the resistance value of resistor R04, C 01 Indicates the capacitance value of capacitor C01, C 02 Represents the capacitance value of capacitor C02.

[0116] It can be understood that the embodiment of the present invention adopts a resistor-capacitor voltage divider network to make the ratio of resistance equal to the inverse of the ratio of capacitance, so that the ratio of reactance remains consistent regardless of high frequency or low frequency, and the voltage signals with fast rising and falling edges can be collected more accurately, thereby achieving precise attenuation of high avalanche voltage and accurately collecting avalanche voltage.

[0117] Signal Conditioning Module

[0118] Signal conditioning modules may include:

[0119] Current op amp conditioning circuit and voltage op amp conditioning circuit.

[0120] The signal conditioning module can use its own current operational amplifier conditioning circuit and voltage operational amplifier conditioning circuit to condition the sampling current and the sampling voltage respectively to obtain a conditioned current signal and a conditioned voltage signal.

[0121] Specifically, the current op amp conditioning circuit, such as Figure 3 As shown, this may include:

[0122] A differential ratio amplification module, a level raising module and a first filter follower module; wherein,

[0123] The differential proportional amplifier module may include:

[0124] Resistor R1, resistor R2, resistor R3, resistor R4 and operational amplifier A1; wherein,

[0125] A first end of the resistor R1 is grounded, and a second end is connected to an inverting input terminal of the operational amplifier A1;

[0126] The first end of the resistor R2 is connected to the second end of the resistor R1, and the second end is connected to the output end of the operational amplifier A1;

[0127] The first end of the resistor R3 is connected to the sampling current, and the second end is connected to the non-inverting input terminal of the operational amplifier A1;

[0128] A first end of the resistor R4 is connected to a second end of the resistor R3, and the second end is grounded;

[0129] The level raising module may include:

[0130] Resistor R5, resistor R7, resistor R8, resistor R9 and operational amplifier A2; wherein,

[0131] A 0.5V voltage signal is input to the first end of the resistor R5, and the second end is connected to the non-inverting input end of the operational amplifier A2;

[0132] A first end of the resistor R7 is connected to the output end of the operational amplifier A1, and a second end of the resistor R7 is connected to the non-inverting input end of the operational amplifier A2;

[0133] A first end of the resistor R8 is grounded, and a second end is connected to an inverting input terminal of the operational amplifier A2;

[0134] A first end of the resistor R9 is connected to the inverting input end of the operational amplifier A2, and a second end of the resistor R9 is connected to the output end of the operational amplifier A2;

[0135] The first filter follower module may include:

[0136] Resistor R10, capacitor C1 and voltage follower A3; wherein,

[0137] A first end of the resistor R10 is connected to the output end of the operational amplifier A2, and a second end of the resistor R10 is connected to the non-inverting input end of the voltage follower A3;

[0138] A first end of the capacitor C1 is connected to a second end of the resistor R10, and the second end is grounded;

[0139] The inverting input terminal of the voltage follower A3 is connected to its own output terminal.

[0140] It can be understood that for the processing of the sampling current representing the avalanche current: the current op amp conditioning circuit uses the differential proportional amplifier module to amplify the sampling current and outputs the first amplified signal; because the avalanche current will have a period of reverse current at the end stage, the second stage uses the level raising module to raise the level of the first amplified signal and output the first raised signal; specifically, it can be selected to raise it by 0.5V so that the subsequent ADC (Analog-to-Digital Converte, analog-to-digital converter) can collect the negative current signal; the last stage uses the first filter follower module to filter and impedance match the first raised signal, and outputs the conditioned current signal V OUT Specifically, the voltage follower A3 is selected for impedance matching, and the active RC composed of the resistor R10 and the capacitor C1 is used for filtering, thereby changing the passive network into an active filtering network to complete the processing of the sampled current. By raising the level of the sampled current corresponding to the avalanche current, the negative avalanche current signal can be collected, which is more accurate than the existing method of only collecting signals above 0V.

[0141] Voltage op amp conditioning circuits, such as Figure 4 As shown, this may include:

[0142] A voltage follower module, an addition module and a second filter follower module; wherein,

[0143] Voltage follower module, which may include:

[0144] Resistor R11 and operational amplifier A4; where,

[0145] The first end of the resistor R11 is connected to the sampling voltage, and the second end is connected to the non-inverting input terminal of the operational amplifier A4;

[0146] The inverting input terminal of the operational amplifier A4 is connected to its own output terminal;

[0147] Addition modules can include:

[0148] Resistor R12, resistor R13, resistor R14, resistor R15 and operational amplifier A5; wherein,

[0149] A 0.5V voltage signal is input to the first end of the resistor R12, and the second end is connected to the non-inverting input end of the operational amplifier A5;

[0150] A first end of the resistor R13 is connected to the output end of the operational amplifier A4, and a second end of the resistor R13 is connected to the non-inverting input end of the operational amplifier A5;

[0151] A first end of the resistor R14 is grounded, and a second end is connected to an inverting input terminal of the operational amplifier A5;

[0152] A first end of the resistor R15 is connected to the inverting input end of the operational amplifier A5, and a second end of the resistor R15 is connected to the output end of the operational amplifier A5;

[0153] The second filter follower module may include:

[0154] Resistor R16, capacitor C2 and voltage follower A6; wherein,

[0155] A first end of the resistor R16 is connected to the output end of the operational amplifier A5, and a second end is connected to the non-inverting input end of the voltage follower A6;

[0156] A first end of the capacitor C2 is connected to a second end of the resistor R16, and the second end is grounded;

[0157] The inverting input terminal of the voltage follower A6 is connected to its own output terminal.

[0158] It can be understood that for the processing of the sampling voltage: due to the existence of the voltage divider resistor in the sampling circuit, the impedance is relatively large, so the first stage of the voltage op amp conditioning circuit uses a voltage follower for impedance matching, so as to output a following voltage according to the sampling voltage. In order to make the voltage and current signals as synchronous as possible without delay, similar to the processing of the current signal, an addition module is added to the second stage to raise the level of the following voltage and output a second raised signal; specifically, it can be selected to raise it by 0.5V; the last stage uses the second filter follower module to filter and impedance match the second raised signal, and outputs a conditioned voltage signal V OUT_V Specifically, the voltage follower A6 is selected for impedance matching, and the active RC composed of the resistor R16 and the capacitor C2 is used for filtering, thereby changing the passive network into an active filtering network to complete the processing of the sampled voltage. For impedance matching, the voltage follower can solve the impedance mismatch problem between the signal source and the load. When the output impedance of the signal source is high and the input impedance of the load is low, the signal output by the signal source will be absorbed by the load, making it impossible for the signal to be transmitted to the load end. By introducing a voltage follower, the output resistance of the signal source can be matched with the input resistance of the load, thereby achieving effective transmission of the signal.

[0159] Analog-to-digital conversion module

[0160] The analog-to-digital conversion module is a conventional ADC, which is used to convert the conditioned current signal into a current digital signal and convert the conditioned voltage signal into a voltage digital signal. The specific structure will not be described in detail here. For details, please refer to the prior art.

[0161] Digital control core module

[0162] The digital control core module is used to charge the inductor in the sampling module, store the received current digital signal and voltage digital signal, and transmit them to the host computer. The digital control core module is also used to control the isolation drive module according to the preset current value to turn on or off the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested.

[0163] Specifically, the digital control core module controls the isolation drive module according to the preset current value to turn on or off the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested, which may include:

[0164] After the digital control core module obtains the preset current value, it controls the isolation drive module to turn on the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested; when the current digital signal reaches the preset current value, it controls the isolation drive module to turn off the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested.

[0165] It can be understood that the digital control core module may include: FPGA (Field Programmable Gate Array) or DSP (Digital Signal Processor). For its specific structure, please refer to the prior art and will not be elaborated here.

[0166] The existing avalanche current is controlled by presetting a MOSFET conduction time to control the maximum avalanche current in the loop. Due to the parasitic parameters in the loop and the conduction characteristics of the device itself, the avalanche current cannot accurately reach the expected current, so it is necessary to make small adjustments repeatedly to gradually approach the expected current. The embodiment of the present invention adopts a method of real-time sampling and analysis of the current signal, monitors the current, and controls the MOSFET to turn off when the avalanche current reaches the preset current value, thereby achieving a more accurate avalanche current and also improving efficiency.

[0167] Isolation driver module

[0168] Since the digital signal of FPGA has insufficient current and driving capability, an isolated driver module is used to enhance its driving capability. Since the voltage and current at the avalanche moment are high and the power is extremely large, in order to avoid breakdown or interference between the power circuit and the driven power supply circuit, an isolated driver module is used to isolate the ground plane between the two circuits.

[0169] Host computer

[0170] It can be understood that the host computer refers to a computer that can directly issue control commands, and various signal changes such as hydraulic pressure, water level, temperature, etc. can be displayed on its screen. In an embodiment of the present invention, the user can use the host computer to set preset parameters, and can also use the host computer to perform integral calculations on the avalanche tolerance according to the received current digital signal, voltage digital signal and preset parameters to obtain the avalanche test results. The host computer can display the avalanche test results on its own screen. The avalanche test results include: avalanche tolerance and waveform display diagram. The preset parameters also include: the current peak value when the inductor is charged in the sampling module, the inductance value of the inductor in the sampling module, and the power supply voltage.

[0171] In the second aspect, corresponding to the above system embodiment, the embodiment of the present invention also provides a MOSFET and diode avalanche test method, the steps of the avalanche test method are shown in FIG. Figure 5 As shown in the flow chart, Figure 6 As shown, combined Figure 5 and Figure 6 It can be seen that the method may include:

[0172] S1, using the host computer to set the preset parameters; the preset parameters include preset current values;

[0173] Preset parameters also include:

[0174] The current peak value when the inductor in the sampling module is charged, the inductance value of the inductor in the sampling module, and the power supply voltage.

[0175] S2, using the digital control core module to control the isolation drive module to turn on the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested;

[0176] After the host computer sets the preset parameters, the digital control core module is used to control the isolation drive module to turn on the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested, and to charge the inductor in the sampling module.

[0177] The working principles of the digital control core module and the isolation drive module can be found in the system implementation examples, which will not be elaborated here.

[0178] S3, using the sampling module to sample the current and voltage corresponding to the MOSFET or the diode to be tested, to obtain the sampled current and the sampled voltage;

[0179] The sampling module is used to meet the measurement and sampling of the current and voltage corresponding to the MOSFET or diode to be tested. The working principle of the sampling module can be found in the system embodiment, which will not be elaborated here.

[0180] S4, using a signal conditioning module to condition the sampled current and the sampled voltage respectively to obtain a conditioned current signal and a conditioned voltage signal, and using an analog-to-digital conversion module to convert the conditioned current signal into a current digital signal and convert the conditioned voltage signal into a voltage digital signal;

[0181] Through the processing of the signal conditioning module, the conditioned current signal and the conditioned voltage signal are made more accurate. For the working principles of the signal conditioning module and the analog-to-digital conversion module, please refer to the system implementation example and will not be elaborated here.

[0182] S5, using the digital control core module to store the received current digital signal and voltage digital signal, when the current digital signal reaches the preset current value, control the isolation drive module to turn off the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested, start the avalanche test, and send the current digital signal and voltage digital signal to the host computer;

[0183] Specifically, when the current digital signal reaches the preset current value, the digital control core module is used to control the isolation drive module to turn off the MOSFET to be tested or the MOSFET in parallel with the diode to be tested, so that the inductor in the sampling module is discharged, the avalanche test is started, and the current digital signal and the voltage digital signal are sent to the host computer.

[0184] Understandable, such as Figure 6 As shown, the digital control core module will detect and store the received current digital signal and voltage digital signal in real time. When the current digital signal does not reach the preset current value, the digital control core module controls the isolation drive module to make the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested continue to be turned on to keep the inductor charged; when the current digital signal reaches the preset current value, the isolation drive module is controlled to turn off the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested, thereby discharging the inductor and starting the avalanche test.

[0185] S6, using the host computer to integrate the avalanche tolerance according to the received current digital signal, voltage digital signal and preset parameters to obtain the avalanche test result; judging the number of current avalanche tests, if the number of current avalanche tests is less than the number of avalanche tests in the preset parameters, return to S2 to continue testing; if the number of current avalanche tests is equal to the number of avalanche tests in the preset parameters, the avalanche test ends.

[0186] Specifically, the avalanche test results may include: avalanche tolerance and waveform display diagram.

[0187] Understandable, such as Figure 6 As shown, after the avalanche is over, the host computer integrates and calculates the avalanche tolerance according to the received current digital signal, voltage digital signal and preset parameters to obtain the avalanche test result. The number of current avalanche tests is judged. If the number of current avalanche tests meets the number of avalanche tests in the preset parameters, the avalanche test ends; if not, return to step S2 and continue to execute S2-S6 until the number of current avalanche tests meets the number of avalanche tests in the preset parameters.

[0188] The embodiment of the present invention can integrate a sampling module, a signal conditioning module, an analog-to-digital conversion module, a digital control core module, an isolation drive module and a host computer on a test board to realize avalanche testing of MOSFET and diodes; utilize the resistor-capacitor voltage divider network in the sampling module to realize accurate collection of voltage signals at fast rising and falling edges; process the sampling current and sampling voltage through the signal conditioning module to realize the collection of negative current signals, thereby greatly improving the accuracy of data; compared with the method of controlling the conduction time of MOSFET to control the maximum avalanche current in the loop, which is mostly adopted in the prior art, the embodiment of the present invention adopts a method of real-time analysis of the current signal, and through real-time monitoring of the current signal, when the avalanche current reaches a preset current value, controls the MOSFET to be turned off, thereby realizing the acquisition of a more accurate avalanche current, while also improving efficiency.

[0189] It should be noted that in the description of the present invention, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0190] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the method embodiment, since it is basically similar to the system embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the system embodiment.

[0191] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A MOSFET and diode avalanche test system, characterized in that: include: Sampling module, signal conditioning module, analog-to-digital conversion module, digital control core module, isolation drive module and host computer; among them, The sampling module is used to sample the current and voltage corresponding to the MOSFET or diode to be tested respectively by using its own sampling resistor and resistor-capacitor voltage divider network to obtain the sampled current and sampled voltage; The signal conditioning module is used to condition the sampled current and sampled voltage respectively using its own current operational amplifier conditioning circuit and voltage operational amplifier conditioning circuit to obtain a conditioned current signal and a conditioned voltage signal; The analog-to-digital conversion module is used to convert the conditioned current signal into a current digital signal, and convert the conditioned voltage signal into a voltage digital signal; The digital control core module is used to control the isolation drive module according to a preset current value to turn on or off the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested; to charge the inductor in the sampling module; to store the received current digital signal and voltage digital signal, and transmit them to the host computer; The host computer is used to set preset parameters; perform integral calculation on avalanche tolerance according to the received current digital signal, voltage digital signal and preset parameters to obtain avalanche test results; the preset parameters include preset current values.

2. A MOSFET and diode avalanche test system according to claim 1, characterized in that: The sampling module comprises: Sampling resistor R01, sampling resistor R02, resistor-capacitor voltage divider network, voltage source, inductor, base corresponding to the MOSFET to be tested and base corresponding to the diode to be tested; wherein, The first end of the sampling resistor R01 is connected to the source of the base corresponding to the MOSFET to be tested, and the second end is grounded; The first end of the sampling resistor R02 is connected to the positive electrode of the base corresponding to the diode to be tested, and the second end is connected to the second end of the sampling resistor R01; The first end of the RC voltage divider network is respectively connected to the cathode of the base corresponding to the diode to be tested and the drain of the base corresponding to the MOSFET to be tested, and the second end is connected to the second end of the sampling resistor R02; The positive terminal of the voltage source is connected to the first end of the inductor, and the negative terminal is connected to the second end of the sampling resistor R01; The second end of the inductor is connected to the drain of the base corresponding to the MOSFET to be tested.

3. A MOSFET and diode avalanche test system according to claim 2, characterized in that: The resistor-capacitor voltage divider network comprises: Resistor R03, resistor R04, capacitor C01 and capacitor C02; wherein, The first end of the resistor R03 is connected to the first end of the capacitor C01, serving as the first end of the resistor-capacitor voltage divider network, and the second end is connected to the second end of the capacitor C01; The first end of the resistor R04 is connected to the second end of the resistor R03, and the second end is connected to the second end of the capacitor C02, serving as the second end of the resistor-capacitor voltage divider network; The first end of the capacitor C02 is connected to the second end of the capacitor C01.

4. A MOSFET and diode avalanche test system according to claim 3, characterized in that: In the resistor-capacitor voltage divider network, the values ​​of the resistor R03, the resistor R04, the capacitor C01 and the capacitor C02 satisfy: Among them, R 03 Indicates the resistance value of resistor R03, R 04 Indicates the resistance value of resistor R04, C 01 Indicates the capacitance value of capacitor C01, C 02 Represents the capacitance value of capacitor C02.

5. The avalanche test system for MOSFET and diode according to claim 1, characterized in that: When an avalanche test is performed on a diode to be tested, a MOSFET connected in parallel with the diode to be tested is arranged at a position corresponding to the MOSFET to be tested.

6. The avalanche test system for MOSFET and diode according to claim 1, characterized in that: The current operational amplifier conditioning circuit comprises: A differential ratio amplification module, a level raising module and a first filter follower module; wherein, The differential ratio amplification module comprises: Resistor R1, resistor R2, resistor R3, resistor R4 and operational amplifier A1; wherein, The first end of the resistor R1 is grounded, and the second end is connected to the inverting input terminal of the operational amplifier A1; The first end of the resistor R2 is connected to the second end of the resistor R1, and the second end is connected to the output end of the operational amplifier A1; The first end of the resistor R3 is connected to the sampling current, and the second end is connected to the non-inverting input end of the operational amplifier A1; The first end of the resistor R4 is connected to the second end of the resistor R3, and the second end is grounded; The level raising module comprises: Resistor R5, resistor R7, resistor R8, resistor R9 and operational amplifier A2; wherein, A 0.5V voltage signal is input to the first end of the resistor R5, and a second end is connected to the non-inverting input end of the operational amplifier A2; The first end of the resistor R7 is connected to the output end of the operational amplifier A1, and the second end is connected to the non-inverting input end of the operational amplifier A2; The first end of the resistor R8 is grounded, and the second end is connected to the inverting input terminal of the operational amplifier A2; The first end of the resistor R9 is connected to the inverting input terminal of the operational amplifier A2, and the second end is connected to the output terminal of the operational amplifier A2; The first filter follower module comprises: Resistor R10, capacitor C1 and voltage follower A3; wherein, The first end of the resistor R10 is connected to the output end of the operational amplifier A2, and the second end is connected to the in-phase input end of the voltage follower A3; The first end of the capacitor C1 is connected to the second end of the resistor R10, and the second end is grounded; The inverting input terminal of the voltage follower A3 is connected to its own output terminal.

7. The avalanche test system for MOSFET and diode according to claim 1, characterized in that: The voltage operational amplifier conditioning circuit comprises: A voltage follower module, an addition module and a second filter follower module; wherein, The voltage follower module comprises: Resistor R11 and operational amplifier A4; where, The first end of the resistor R11 is connected to the sampling voltage, and the second end is connected to the non-inverting input end of the operational amplifier A4; The inverting input terminal of the operational amplifier A4 is connected to its own output terminal; The addition module comprises: Resistor R12, resistor R13, resistor R14, resistor R15 and operational amplifier A5; wherein, A 0.5V voltage signal is input to the first end of the resistor R12, and a second end is connected to the non-inverting input end of the operational amplifier A5; The first end of the resistor R13 is connected to the output end of the operational amplifier A4, and the second end is connected to the non-inverting input end of the operational amplifier A5; The first end of the resistor R14 is grounded, and the second end is connected to the inverting input terminal of the operational amplifier A5; The first end of the resistor R15 is connected to the inverting input end of the operational amplifier A5, and the second end is connected to the output end of the operational amplifier A5; The second filter follower module comprises: Resistor R16, capacitor C2 and voltage follower A6; wherein, The first end of the resistor R16 is connected to the output end of the operational amplifier A5, and the second end is connected to the non-inverting input end of the voltage follower A6; The first end of the capacitor C2 is connected to the second end of the resistor R16, and the second end is grounded; The inverting input terminal of the voltage follower A6 is connected to its own output terminal.

8. The avalanche test system for MOSFET and diode according to claim 1, characterized in that: The digital control core module controls the isolation drive module according to a preset current value to turn on or off the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested, including: After the digital control core module obtains the preset current value, it controls the isolation drive module to turn on the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested; when the current digital signal reaches the preset current value, it controls the isolation drive module to turn off the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested.

9. A method for avalanche testing of MOSFET and diode, characterized in that: Applied to the avalanche testing system according to any one of claims 1 to 8, the method comprises: S1, using a host computer to set preset parameters; the preset parameters include preset current values; S2, using the digital control core module to control the isolation drive module to turn on the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested; S3, using the sampling module to sample the current and voltage corresponding to the MOSFET or the diode to be tested, to obtain the sampled current and the sampled voltage; S4, using a signal conditioning module to condition the sampled current and the sampled voltage respectively to obtain a conditioned current signal and a conditioned voltage signal, and using an analog-to-digital conversion module to convert the conditioned current signal into a current digital signal and convert the conditioned voltage signal into a voltage digital signal; S5, using the digital control core module to store the received current digital signal and voltage digital signal, when the current digital signal reaches the preset current value, control the isolation drive module to turn off the MOSFET to be tested or the MOSFET connected in parallel with the diode to be tested, start the avalanche test, and send the current digital signal and voltage digital signal to the host computer; S6, using the upper computer to integrate the avalanche tolerance according to the received current digital signal, voltage digital signal and preset parameters to obtain the avalanche test result; judging the number of current avalanche tests, if the number of current avalanche tests is less than the number of avalanche tests in the preset parameters, return to S2 to continue testing; if the number of current avalanche tests is equal to the number of avalanche tests in the preset parameters, the avalanche test ends.

10. A MOSFET and diode avalanche test method according to claim 9, characterized in that: The preset parameters also include: The current peak value when the inductor in the sampling module is charged, the inductance value of the inductor in the sampling module, and the power supply voltage.

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