CN-122017303-A - Protection method and system for dynamic test circuit based on energy accumulation of shunt

CN122017303ACN 122017303 ACN122017303 ACN 122017303ACN-122017303-A

Abstract

The invention discloses a protection method of a dynamic test circuit based on energy accumulation of a shunt, which comprises the following steps of calibrating key model parameters through experiments, synchronously collecting multiple physical quantities, carrying out real-time temperature correction and current conversion on the resistance value of the shunt, carrying out parallel calculation on the energy accumulation of the shunt, adaptively generating a dynamic energy threshold value, determining whether to carry out narrow pulse triggering and switching-off after comparing the threshold value, reporting event records and carrying out conditional resetting. The protection system of the dynamic test circuit based on the energy accumulation of the shunt comprises an operation control unit, wherein the operation control unit is respectively connected with an execution driving unit, a signal sensing unit and a state feedback unit, and the execution driving unit is connected with a device to be tested. The protection method and the system of the dynamic test circuit based on the energy accumulation of the current divider take the energy accumulation of the current divider as a protection criterion and introduce temperature compensation and heat dissipation items, so that the error protection probability caused by normal pulse current in the dynamic test can be remarkably reduced.

Inventors

YANG YUAN
HUI ZIXUAN
DU XINGFENG
ZHANG CHENXI
KANG RUI
GENG QI
TANG ZIXIANG

Assignees

西安理工大学

Dates

Publication Date: 20260512
Application Date: 20260403

Claims (10)

1. The protection method of the dynamic test circuit based on the energy accumulation of the shunt is characterized by comprising the following steps: step 1, experimental calibration key model parameters; step2, synchronously collecting multiple physical quantities; Step3, real-time temperature correction and current conversion of the shunt resistance value; Step4, parallel calculation of energy accumulation of the shunt; step5, adaptively generating a dynamic energy threshold; step 6, determining whether to perform narrow pulse triggering turn-off after threshold comparison; And 7, reporting the event record and conditionally resetting.
2. The method for protecting a dynamic test circuit based on energy accumulation of a shunt according to claim 1, wherein said step 1 comprises: Step 1.1, calibrating a resistance-temperature model; Measuring the shunt resistance at different temperature points and fitting to obtain the shunt resistance at the reference temperature First order temperature coefficient Second order temperature coefficient : Step 1.2, calibrating thermal parameters; obtaining a temperature rise curve through a constant current heating experiment and obtaining a thermal model parameter of the shunt through a data fitting method; step 1.3, calibrating an environment correction coefficient; Testing the energy tolerance limit of the shunt under the combination of temperature and humidity of different environments, and obtaining key parameters in an environment correction factor model by a data fitting method, wherein the key parameters in the environment correction factor model comprise temperature correction coefficients Coefficient of humidity correction ; And 1.4, writing calibrated parameters into an operation control unit on line through a state feedback unit to realize threshold self-adaption under different current splitters and different test working conditions.
3. The method for protecting a dynamic test circuit based on energy accumulation of a shunt according to claim 1, wherein the step 2 comprises outputting a synchronous clock trigger signal by the operation control unit by using a synchronous trigger sampling mechanism, and synchronously collecting differential voltage sampling values of the shunt by the driving signal sensing unit And the temperature sampling value of the shunt Sampling period is 。
4. The method for protecting a dynamic test circuit based on energy accumulation of a shunt according to claim 1, wherein said step 3 comprises: the temperature sampling value of the shunt acquired according to the step 2 The current divider resistance value is corrected in real time through a current divider resistance value temperature correction model, and then the current divider differential voltage sampling value is combined Converting to obtain real-time loop current ; When the operation control unit corrects the resistance value of the shunt in real time according to the temperature sampling value, the resistance value temperature correction model adopts a first-order form or a second-order form, and the calculation formula of the first-order form is as follows: , In the formula, Indicating a temperature of The current divider resistance value; indicating a reference temperature The resistance value of the lower current divider is equal to that of the upper current divider, Representing a first order temperature coefficient; Representing real-time temperature; representing a reference temperature; the second-order form of the calculation formula is: , Wherein, the Indicating a temperature of The current divider resistance value; At a reference temperature The lower shunt resistance; is a first order temperature coefficient; is a second-order temperature coefficient; Representing real-time temperature; representing a reference temperature; loop real-time current The calculation formula converted according to ohm's law is as follows: , Wherein, the Representation of Real-time current at a moment; Representation of Differential voltage sampling value of the shunt at moment; Representation of And the current divider resistance value after temperature correction at the moment.
5. The method for protecting a dynamic test circuit based on energy accumulation of a shunt according to claim 1, wherein said step 4 comprises: Real-time current through loop And corrected shunt resistance Calculating current divider instantaneous power dissipation And discrete integration is performed to obtain the energy accumulation of the shunt ; Step 4.1, calculating the instantaneous power dissipation of the shunt; the current divider instantaneous power dissipation is: (4), In the formula, Representation of Instantaneous power dissipation of the shunt at the moment; Representation of Real-time current at a moment; Representation of The shunt resistance value after temperature correction at any time; Step 4.2, performing discrete integration on the energy accumulation amount; the energy accumulation may be accumulated as discrete integral: when the heat dissipation term is not subtracted, the calculation formula of the energy accumulation amount is: (5), In the formula, Representation of Time-of-day energy accumulation; Representation of Time-of-day energy accumulation; Representation of Instantaneous power dissipation of the shunt at the moment; Representing a sampling period; Introducing a heat dissipation power term And when calculating the net energy increment, the calculation formula of the energy accumulation amount is as follows: (6), In the formula, Representation of Time-of-day energy accumulation; Representation of Time-of-day energy accumulation; Representation of Instantaneous power dissipation of the shunt at the moment; Representation of A heat dissipation power term at a moment; Representing a sampling period; Heat dissipation power term The method can be obtained by adopting an equivalent thermal resistance model or a convective heat transfer model: When the equivalent thermal resistance model is adopted for acquisition, the calculation formula of the heat dissipation power term is as follows: , In the formula, Representation of A heat dissipation power term at a moment; Is that A shunt temperature sampling value at the moment; Is that Sampling the ambient temperature at the moment; Is equivalent thermal resistance; when the heat convection model is obtained, the calculation formula of the heat dissipation power term is as follows: (8), In the formula, Representation of A heat dissipation power term at a moment; is the product of the equivalent heat exchange coefficient and the area; Is that A shunt temperature sampling value at the moment; Is that The ambient temperature at that time samples.
6. The method for protecting a dynamic test circuit based on energy accumulation of a shunt according to claim 1, wherein said step 5 comprises: the calculation formula for generating the dynamic energy threshold value based on the thermal safety model of the shunt by the operation control unit is as follows: , Wherein, the Is a dynamic energy threshold; Equivalent heat capacity of the shunt; is the maximum allowable temperature; Is that A shunt temperature sampling value at the moment; Is an environmental correction factor; Environmental correction factor Related to ambient temperature, or to ambient temperature, ambient humidity, ambient correction factors Is limited in a preset interval To avoid threshold overcorrection; The calculation formula for the environment correction factor related to the environment temperature is: (10), Wherein, the Is an environmental correction factor; Is a temperature correction coefficient; Is that Sampling the ambient temperature at the moment; is the reference ambient temperature; the calculation formula of the environment correction factor related to the environment temperature and the environment humidity is as follows: (11), Wherein, the Is an environmental correction factor; Is a temperature correction coefficient; is a humidity correction coefficient; Is that Sampling the ambient temperature at the moment; is the reference ambient temperature; Is that Sampling values of environmental humidity at moment; Is the reference ambient humidity.
7. The method for protecting a dynamic test circuit based on energy accumulation of a shunt according to claim 1, wherein the step 6 comprises the step of the operation control unit accumulating the energy obtained in the step 4 And the dynamic energy threshold value obtained in the step 5 After comparison, determining whether to perform narrow pulse triggering and switching off, if the triggering condition is met, the pulse command generating module outputs a switching off pulse command, and if the triggering condition is not met, the operation control unit continuously monitors the energy accumulation amount And dynamic energy threshold The off pulse instruction is not output, and the normal operation of the test loop is kept; The triggering conditions of the narrow pulse triggering turn-off are as follows: (12), Wherein, the Representation of Time-of-day energy accumulation; is a dynamic energy threshold; indicating a hysteresis section, and setting the hysteresis section To avoid critical jitter; the turn-off pulse is a single narrow pulse, and the pulse width is a preset nanosecond pulse width or a preset sub-microsecond pulse width.
8. The method for protecting a dynamic test circuit based on energy accumulation of a shunt according to claim 1, wherein the step 7 comprises the steps that after the protection is triggered, a state feedback unit records and uploads event data, and if a reset condition is met, a reset pulse is output to release the latch; the event data comprises a trigger energy value, a peak current value, a delay time from the trigger to the off and the retry times, and the reset condition comprises that the temperature of the shunt is not higher than a preset reset temperature threshold value and the energy accumulation amount is not higher than a preset proportion of a dynamic energy threshold value.
9. The protection system of the dynamic test circuit based on the energy accumulation of the current divider is characterized by comprising an operation control unit, wherein the operation control unit is respectively connected with an execution driving unit, a signal sensing unit and a state feedback unit, and the execution driving unit is connected with a device to be tested; The tested device, the Kelvin four-terminal current divider, the temperature sensor, the series executive switching device and the power supply are connected in series to form a closed loop, the power supply is connected in parallel with the capacitor C 1 , and the series executive switching device is connected in parallel with the peak suppression network.
10. The protection system of the dynamic test circuit based on the energy accumulation of the shunt according to claim 9, wherein the operation control unit comprises an FPGA core control chip, and a resistance temperature correction module, an energy parallel integration module, a dynamic threshold generation module, a threshold comparison module, a protection latch module, a pulse instruction generation module and a state monitoring and counting module are arranged in the FPGA core control chip; The execution driving unit comprises a signal generator and a driving plate, wherein the signal generator is connected with the driving plate, the signal generator is connected with the pulse instruction generation module, and the driving plate is connected with a tested device and a serial execution switching device; The signal sensing unit comprises an analog-to-digital conversion circuit, the analog-to-digital conversion circuit is connected with the FPGA core control chip, the analog-to-digital conversion circuit is respectively connected with a differential sampling circuit and a temperature sensor, and the differential sampling circuit is connected with a Kelvin four-terminal shunt; the state feedback unit comprises an upper computer communication module which is respectively connected with the acousto-optic alarm module and the FPGA core control chip.

Description

Protection method and system for dynamic test circuit based on energy accumulation of shunt Technical Field The invention belongs to the technical field of power electronic dynamic test circuit protection, relates to a protection method of a dynamic test circuit based on energy accumulation of a current divider, and further relates to a protection system of the dynamic test circuit based on energy accumulation of the current divider. Background With the wide application of wide bandgap power devices (such as gallium nitride, silicon carbide, etc.), dynamic characteristic tests (such as switching loss, reverse recovery, gate reliability, etc.) have become key links for device evaluation and system optimization. Dynamic test circuits typically require high amplitude, high frequency current pulses to be applied in nanoseconds to microseconds to simulate electrical stress under real conditions. In the process, the current divider connected in series with the main loop is used as a key current sensing element, so that high-bandwidth and high-precision current measurement is needed, and severe temperature rise caused by transient high current is also needed to be born. If the shunt is overheated to cause resistance drift, welding spot failure and even burn out, the accuracy of test data is directly affected, and even the test system fault is caused. The existing test circuit protection scheme mainly has the following limitations when facing a dynamic test scene: The protection criterion is mismatched with the dynamic working condition, the traditional overcurrent protection adopts a fixed current threshold value, and the normal pulse heavy current and dangerous fault current in the dynamic test cannot be distinguished, so that the error protection is extremely easy to cause, and the test flow is interrupted. While the protection strategy based on the fixed joule integral considers the energy accumulation effect, the threshold is static, and cannot adapt to the initial temperature of the shunt, the real-time heat dissipation condition and the difference of dynamic current waveforms, so that under protection or over protection is often caused. The response speed of the system is insufficient, and many schemes rely on a microcontroller (Micro controller Unit, MCU) to perform signal processing and protection logic judgment. The serial instruction execution architecture of the MCU leads to that the time delay of a full link from sampling and calculation to sending a shutdown instruction is generally more than microsecond, the protection requirement of nanosecond quick faults possibly occurring in dynamic testing is difficult to be met, and the risk of response lag exists. The anti-interference performance of the turn-off execution mode is poor, and the existing protection mostly adopts a simple level signal to directly drive the turn-off device. In a high-frequency and high-noise electromagnetic environment for dynamic test, the level signal is easy to interfere to generate jitter, and can cause false turn-off or incomplete turn-off, so that the reliability of the test and the integrity of data are affected. Disclosure of Invention The invention aims to provide a protection method of a dynamic test circuit based on shunt energy accumulation, which solves the problems of test interruption, data failure and equipment damage caused by mismatching of protection strategies, out-of-control fault current, response delay and unreliable execution in dynamic test in the prior art. Another object of the invention is a protection system for a dynamic test circuit based on shunt energy accumulation. The technical scheme adopted by the invention is that the protection method of the dynamic test circuit based on energy accumulation of the current divider comprises the following steps: step 1, experimental calibration key model parameters; step2, synchronously collecting multiple physical quantities; Step3, real-time temperature correction and current conversion of the shunt resistance value; Step4, parallel calculation of energy accumulation of the shunt; step5, adaptively generating a dynamic energy threshold; step 6, determining whether to perform narrow pulse triggering turn-off after threshold comparison; And 7, reporting the event record and conditionally resetting. The invention is also characterized in that: the step 1 comprises the following steps: Step 1.1, calibrating a resistance-temperature model; Measuring the shunt resistance at different temperature points and fitting to obtain the shunt resistance at the reference temperature First order temperature coefficientSecond order temperature coefficient: Step 1.2, calibrating thermal parameters; obtaining a temperature rise curve through a constant current heating experiment and obtaining a thermal model parameter of the shunt through a data fitting method; step 1.3, calibrating an environment correction coefficient; Testing the energy tolerance limit of the shunt under the