Protection method and system for dynamic test circuit based on shunt energy accumulation

Abstract

The application discloses a protection method of a dynamic test circuit based on shunt energy accumulation, and comprises the following steps: experimentally calibrating key model parameters; synchronously collecting multiple physical quantities; real-time temperature correction and current conversion of shunt resistance; parallel calculation of shunt energy accumulation; adaptive generation of dynamic energy threshold; determination of whether to perform narrow pulse trigger shutdown after threshold comparison; event record reporting and conditional reset. The protection system of the dynamic test circuit based on shunt energy accumulation comprises an operation control unit, which is connected with an execution driving unit, a signal sensing unit and a state feedback unit respectively, and the execution driving unit is connected with a measured device. The protection method and system of the dynamic test circuit based on shunt energy accumulation take shunt energy accumulation as a protection criterion and introduce temperature compensation and heat dissipation items, so that the false protection probability caused by normal pulse current in dynamic test can be significantly reduced.

Description

Technical Field

[0001] This invention belongs to the field of power electronic dynamic test circuit protection technology, and relates to a protection method for dynamic test circuits based on shunt energy accumulation, as well as a protection system for dynamic test circuits based on shunt energy accumulation. Background Technology

[0002] With the widespread application of wide-bandgap power devices (such as gallium nitride and silicon carbide), dynamic characteristic testing (such as switching losses, reverse recovery, and gate reliability) has become a critical aspect of device evaluation and system optimization. Dynamic test circuits typically apply high-amplitude, high-frequency current pulses within nanoseconds to microseconds to simulate electrical stress under real-world operating conditions. During this process, the shunt connected in series in the main circuit, as a critical current sensing element, must not only provide high-bandwidth, high-precision current measurement but also withstand the severe temperature rise caused by transient large currents. If the shunt overheats, causing resistance drift, solder joint failure, or even burnout, it will directly affect the accuracy of the test data and may even lead to test system failure.

[0003] Existing test circuit protection schemes have the following limitations when facing dynamic test scenarios: Mismatch between protection criteria and dynamic operating conditions: Traditional overcurrent protection uses a fixed current threshold, which cannot distinguish between normal pulsed high current and dangerous fault current in dynamic testing, easily leading to false protection and interrupting the test process. While protection strategies based on fixed Joule integrals take into account the energy accumulation effect, their static thresholds cannot adapt to the initial temperature of the shunt, real-time heat dissipation conditions, and differences in dynamic current waveforms, often resulting in under-protection or over-protection.

[0004] Insufficient system response speed: Many solutions rely on microcontroller units (MCUs) for signal processing and protection logic judgment. The serial instruction execution architecture of MCUs results in a total latency of microseconds or more from sampling and calculation to issuing shutdown instructions, which is difficult to meet the protection requirements of nanosecond-level rapid faults that may occur in dynamic testing, and there is a risk of response lag.

[0005] Poor anti-interference capability of shutdown execution method: Existing protection systems mostly use simple level signals to directly drive shutdown devices. In the high-frequency, high-noise electromagnetic environment of dynamic testing, the level signal is easily affected by interference and jitter, which may lead to false shutdown or incomplete shutdown, affecting the reliability of the test and the integrity of the data. Summary of the Invention

[0006] The purpose of this invention is to provide a protection method for dynamic test circuits based on shunt energy accumulation, which solves the problems of test interruption, data failure and equipment damage caused by protection strategy mismatch, fault current runaway, response lag and unreliable execution in the prior art during dynamic testing.

[0007] Another objective of this invention is a protection system based on a dynamic test circuit for shunt energy accumulation.

[0008] The technical solution adopted in this invention is a protection method for a dynamic test circuit based on shunt energy accumulation, comprising the following steps: Step 1: Experimentally calibrate key model parameters; Step 2: Simultaneously acquire multiple physical quantities; Step 3: Real-time temperature correction and current conversion of shunt resistance; Step 4: Parallel calculation of shunt energy accumulation; Step 5: Adaptively generate dynamic energy threshold; Step 6: After threshold comparison, determine whether to perform narrow pulse trigger shutdown; Step 7: Event logging and conditional reset.

[0009] The invention is further characterized by: Step 1 includes: Step 1.1: Shunt resistance temperature correction model calibration; The shunt resistance was measured at different temperature points and fitted to obtain the shunt resistance at the reference temperature. First-order temperature coefficient Second-order temperature coefficient : Step 1.2: Thermal parameter calibration; Temperature rise curves were obtained through constant current heating experiments, and the parameters of the shunt thermal safety model were obtained through data fitting methods. Step 1.3: Environmental correction factor calibration; The energy tolerance limit of the shunt was tested under different combinations of temperature and humidity in various environments, and key parameters in the environmental correction factor model were obtained through data fitting methods. Key parameters in the environmental correction factor model include the temperature correction coefficient. Humidity correction factor ; Step 1.4: After calibration, the parameters are written online to the operation and control unit through the status feedback unit to achieve threshold adaptation under different shunts and different test conditions.

[0010] Step 2 includes: employing a synchronous trigger sampling mechanism, whereby the operation and control unit outputs a synchronous clock trigger signal to drive the signal sensing unit to synchronously acquire the differential voltage sampling value of the shunt. With shunt temperature sampling value The sampling period is .

[0011] Step 3 includes: Based on the shunt temperature sampling values ​​collected in step 2 The shunt resistance is corrected in real time using a shunt resistance temperature correction model, combined with the shunt differential voltage sampling value. The real-time current of the loop is obtained by conversion. ; When the operational control unit corrects the shunt resistance in real time based on the temperature sampling value, the resistance temperature correction model can be in first-order or second-order form. The calculation formula for the first-order form is as follows: , In the formula, Indicates temperature as The shunt resistance value at that time; Indicates reference temperature The shunt resistance value is below; Indicates the first-order temperature coefficient; Indicates real-time temperature; Indicates the reference temperature; The formula for calculating the second-order form is: , in, Indicates temperature as The shunt resistance value at that time; Reference temperature The shunt resistance value is below; It is a first-order temperature coefficient; It is a second-order temperature coefficient; Indicates real-time temperature; Indicates the reference temperature; Real-time current of the loop The formula for calculation based on Ohm's law is: , in, express Real-time current at any given moment; express The sampled value of the shunt differential voltage at time t; express The shunt resistance value after temperature correction at any given time.

[0012] Step 4 includes: Real-time current through the loop With the corrected shunt resistance value Calculate the instantaneous power dissipation of the shunt Discrete integration is then performed to obtain the shunt energy accumulation. ; Step 4.1: Calculate the instantaneous power dissipation of the shunt; The instantaneous power dissipation of the shunt is: (4), In the formula, express Instantaneous power dissipation of the shunt at any given moment; express Real-time current at any given moment; express The shunt resistance value after temperature correction at any given time; Step 4.2: Perform discrete integration on the accumulated energy; The energy accumulation can be summed using discrete integrals: Without deducting heat dissipation, the formula for calculating the cumulative energy is: (5), In the formula, express The amount of energy accumulated at any given moment; express The amount of energy accumulated at any given moment; express Instantaneous power dissipation of the shunt at any given moment; Indicates the sampling period; Introducing the heat dissipation power term When calculating the net energy increment, the formula for calculating the energy accumulation is: (6), In the formula, express The amount of energy accumulated at any given moment; express The amount of energy accumulated at any given moment; express Instantaneous power dissipation of the shunt at any given moment; express The heat dissipation power at any given time; Indicates the sampling period; Heat dissipation power item The equivalent thermal resistance model or the convection heat transfer model can be used to obtain the following: When using the equivalent thermal resistance model, the formula for calculating the heat dissipation power term is: , In the formula, express The heat dissipation power at any given time; for The shunt temperature sample value at that moment; for Ambient temperature sample value at any given time; Equivalent thermal resistance; When obtaining the convective heat transfer model, the formula for calculating the heat dissipation power term is: (8), In the formula, express The heat dissipation power at any given time; It is the product of the equivalent heat transfer coefficient and the area; for The shunt temperature sample value at that moment; for The ambient temperature sample value at any given time.

[0013] Step 5 includes: The calculation formula for the dynamic energy threshold generated by the operation and control unit based on the shunt thermal safety model is as follows: , in, The dynamic energy threshold; The equivalent heat capacity of the shunt; Maximum permissible temperature; for The shunt temperature sample value at that moment; Environmental correction factor; Environmental Correction Factors Environmental correction factor, which is related to ambient temperature or ambient temperature and humidity. Limited to a preset range To avoid over-correction of the threshold; The formula for calculating the environmental correction factor when it is related to ambient temperature is: (10) in, Environmental correction factor; This is a temperature correction factor; for Ambient temperature sample value at any given time; For reference ambient temperature; The formula for calculating the environmental correction factor when it is related to ambient temperature and humidity is as follows: (11), in, Environmental correction factor; This is a temperature correction factor; This is the humidity correction factor; for Ambient temperature sample value at any given time; For reference ambient temperature; for Ambient humidity sample value at any given time; For reference ambient humidity.

[0014] Step 6 includes: the computational control unit accumulating the energy obtained in step 4. Compared with the dynamic energy threshold obtained in step 5 After comparison, it is determined whether to perform narrow-pulse triggered shutdown; if the triggering conditions are met, the pulse command generation module outputs a shutdown pulse command; if the triggering conditions are not met, the operation and control unit will continue to monitor the energy accumulation. With dynamic energy threshold It does not output a shutdown pulse command, and keeps the test circuit running normally; The triggering condition for narrow pulse trigger shutdown is: (12) in, express The amount of energy accumulated at any given moment; The dynamic energy threshold; Indicate the hysteresis interval, set the hysteresis interval To avoid critical jitter; The shutdown pulse is a single narrow pulse with a preset nanosecond or submicrosecond pulse width.

[0015] Step 7 includes: After protection is triggered, the status feedback unit records and uploads event data. If the reset condition is met, a reset pulse is output to release the latch; if the reset condition is not met, the protection latch module will continue to remain in the off state, waiting for the reset condition to be met or for manual intervention. Event data includes trigger energy value, peak current value, delay time from trigger to shutdown, and number of retries; reset conditions include shunt temperature not exceeding a preset reset temperature threshold and energy accumulation not exceeding a preset proportion of the dynamic energy threshold.

[0016] Another technical solution adopted in this invention is a protection system for a dynamic test circuit based on shunt energy accumulation, including an operation and control unit, which is connected to an execution drive unit, a signal sensing unit, and a status feedback unit, respectively, and the execution drive unit is connected to the device under test. The device under test, together with the Kelvin four-terminal shunt, temperature sensor, series-connected actuator, and power supply, form a closed loop. The power supply is connected in parallel with capacitor C1, and the series-connected actuator is connected in parallel with the spike suppression network.

[0017] Another feature of the technical solution of this invention is that: The operation and control unit includes an FPGA (Field-Programmable Gate Array) core control chip. The FPGA core control chip contains 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 command generation module, and a status monitoring and counting module. The execution drive unit includes a signal generator and a drive board. The signal generator and the drive board are connected. The signal generator is connected to the pulse command generation module. The drive board is connected to the device under test and the series execution switch device. The signal sensing unit includes an analog-to-digital converter circuit, which is connected to the FPGA core control chip. The analog-to-digital converter circuit is also connected to a differential sampling circuit and a temperature sensor. The differential sampling circuit is connected to a Kelvin four-terminal shunt. The status feedback unit includes a host computer communication module, which is connected to the audible and visual alarm module and the FPGA core control chip.

[0018] The beneficial effects of this invention are: Using the shunt energy accumulation as the protection criterion and introducing temperature compensation and heat dissipation terms can significantly reduce the probability of false protection caused by normal pulse current in dynamic testing. By employing parallel computation with programmable logic devices and hardware-level comparison triggering, the latency of sampling, calculation, and triggering links can be reduced, thereby improving the protection coverage against rapid faults. The shutdown command uses narrow pulse triggering and can be combined with latch-up and hysteresis suppression, which helps to enhance the anti-interference reliability in high-noise electromagnetic environments. It supports dynamic threshold and environmental temperature and humidity correction as well as online calibration, improving adaptability and repeatability under different initial temperatures, heat dissipation conditions and waveform conditions. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the protection system based on the dynamic test circuit of the shunt energy accumulation of the present invention. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0021] Example 1 This embodiment proposes a protection method for a dynamic test circuit based on shunt energy accumulation, including the following steps: Step 1: Experimentally calibrate key model parameters; Step 2: Simultaneously acquire multiple physical quantities; Step 3: Real-time temperature correction and current conversion of shunt resistance; Step 4: Parallel calculation of shunt energy accumulation; Step 5: Adaptively generate dynamic energy threshold; Step 6: After threshold comparison, determine whether to perform narrow pulse trigger shutdown; Step 7: Event logging and conditional reset.

[0022] Example 2 Based on Example 1, this example proposes step 1: experimental calibration of key model parameters; To improve the accuracy and scenario adaptability of protection thresholds, key model parameters were calibrated through experiments: Step 1.1: Shunt resistance temperature correction model calibration; The shunt resistance was measured at different temperature points and fitted to obtain the shunt resistance at the reference temperature. First-order temperature coefficient Second-order temperature coefficient : The shunt is placed in a high-precision temperature-controlled chamber. At multiple preset temperature points (e.g., 0℃, 25℃, 50℃, 75℃, 100℃, 125℃, etc.), the resistance of the shunt is measured using a high-precision resistance meter. The measured temperature-resistance data points are then input into data processing software (such as MATLAB (Matrix Laboratory) or Origin data analysis software). The least squares method is used to perform curve fitting on a first-order or second-order model to obtain the shunt resistance value. First-order temperature coefficient Second-order temperature coefficient When fitting the data, a first-order or second-order model can be selected based on the material properties of the shunt and the required accuracy. In one embodiment of the present invention: Shunt model: A certain high-precision manganese copper shunt; Reference temperature 25℃; Shunt resistance at reference temperature 10mΩ; First-order temperature coefficient : / ℃; Second-order temperature coefficient : / ℃²; Step 1.2: Thermal parameter calibration; Temperature rise curves were obtained through constant current heating experiments, and the parameters of the shunt thermal safety model were obtained through data fitting methods. If the shunt primarily dissipates heat through heat conduction, and the thermal model can be simplified to a lumped parameter model, the fitted thermal model parameters are the equivalent heat capacity. With equivalent thermal resistance If the splitter primarily dissipates heat through convection, and a more precise description of its heat exchange process with the environment is required, the fitted thermal model parameters are the product of the equivalent heat transfer coefficient and the area. ; The thermal safety model parameters of the shunt are obtained by data fitting: the shunt is placed at a constant ambient temperature, a constant current is passed through it to make it heat up, and the temperature change curve of the shunt is monitored in real time. The measured temperature-time data points are input into the data processing software, and the thermal model parameters are obtained by fitting the thermal model established based on the thermal balance principle of the shunt. In one embodiment of the present invention: Heat dissipation method: mainly through heat conduction, simplified to a lumped parameter model; Equivalent heat capacity 0.5 J / ℃; 20℃ / W; Step 1.3: Environmental correction factor calibration; The energy tolerance limit of the shunt was tested under different combinations of temperature and humidity in various environments, and key parameters in the environmental correction factor model were obtained through data fitting methods. Key parameters in the environmental correction factor model include the temperature correction coefficient. Humidity correction factor ; Key parameters in the environmental correction factor model are obtained through data fitting: In a controlled environmental temperature and humidity chamber, the shunt is placed under different combinations of ambient temperature and humidity (e.g., normal temperature and humidity, high temperature and high humidity, low temperature and low humidity), and current pulses of different amplitudes and durations are applied to the shunt until it reaches its thermal damage limit (e.g., permanent resistance drift or burnout). The maximum energy accumulation that the shunt can withstand under different environmental conditions is recorded. These data points are input into data processing software, and the temperature correction coefficient is obtained by fitting the physical model of the environmental correction factor. Humidity correction factor ; In one embodiment of the present invention: Reference ambient temperature 25℃; Reference ambient humidity 50%RH; Temperature correction factor : / ℃; Humidity correction factor : / %RH; Step 1.4: After calibration, the parameters are written online to the operation and control unit through the status feedback unit to achieve threshold adaptation under different shunts and different test conditions.

[0023] Example 3 Based on Example 1, this example proposes step 2: synchronous acquisition of multiple physical quantities; A synchronous trigger sampling mechanism is adopted, in which the operation and control unit outputs a synchronous clock trigger signal to drive the signal sensing unit to synchronously acquire the differential voltage sampling value of the shunt. With shunt temperature sampling value The sampling period is ; In one embodiment of the present invention: Sampling period 100ns (nanosecond); Example 4 Based on Example 1, this example proposes step 3: real-time temperature correction and current conversion of shunt resistance; Based on the shunt temperature sampling values ​​collected in step 2 The shunt resistance is corrected in real time using a shunt resistance temperature correction model, combined with the shunt differential voltage sampling value. The real-time current of the loop is obtained by conversion. ; When the operational control unit corrects the shunt resistance in real time based on the temperature sampling value, the resistance temperature correction model can be in first-order or second-order form. The calculation formula for the first-order form is as follows: , In the formula, Indicates temperature as The shunt resistance value at that time; Indicates reference temperature The shunt resistance value is below; Indicates the first-order temperature coefficient; Indicates real-time temperature; Indicates the reference temperature; The formula for calculating the second-order form is: , in, Indicates temperature as The shunt resistance value at that time; Reference temperature The shunt resistance value is below; It is a first-order temperature coefficient; It is a second-order temperature coefficient; Indicates real-time temperature; Indicates the reference temperature; The first-order form is suitable for scenarios with a small temperature variation range, such as the shunt operating temperature range within T0±30℃, or for scenarios where the accuracy requirements are not extremely high, such as allowing a resistance correction error of less than 1%. The second-order form is suitable for scenarios with a large temperature variation range, such as the shunt operating temperature range exceeding T0±30℃, or for scenarios where the accuracy requirements are high, such as requiring a resistance correction error of less than 0.1%. Real-time current of the loop The formula for calculation based on Ohm's law is: , in, express Real-time current at any given moment; express The sampled value of the shunt differential voltage at time t; express The shunt resistance value after temperature correction at any given time.

[0024] At a certain moment in a certain embodiment of the present invention : Shunt temperature sampling value 75℃; Shunt differential voltage sampling value 100mV; According to the temperature correction model formula (2) for the resistance of a second-order shunt: ; ; ; mΩ; Formula (3) for converting the real-time current of the circuit according to Ohm's law: ; A; Example 5 Based on Example 1, this example proposes step 4: parallel calculation of the shunt energy accumulation; Real-time current through the loop With the corrected shunt resistance value Calculate the instantaneous power dissipation of the shunt Discrete integration is then performed to obtain the shunt energy accumulation. ; Step 4.1: Calculate the instantaneous power dissipation of the shunt; The instantaneous power dissipation of the shunt is: (4), In the formula, express Instantaneous power dissipation of the shunt at any given moment; express Real-time current at any given moment; express The shunt resistance value after temperature correction at any given time; Step 4.2: Perform discrete integration on the accumulated energy; The energy accumulation can be summed using discrete integrals: Without deducting heat dissipation (applicable to short pulses, such as pulse widths no greater than 100μs, or scenarios where heat dissipation has a small impact, such as when the shunt temperature rise rate is much greater than the heat dissipation rate), the formula for calculating the energy accumulation is: (5), In the formula, express The amount of energy accumulated at any given moment; express The amount of energy accumulated at any given moment; express Instantaneous power dissipation of the shunt at any given moment; Indicates the sampling period; Introducing the heat dissipation power term When calculating the net energy increment (applicable to long pulses, such as pulse widths greater than 100μs, or scenarios where heat dissipation has a significant impact, such as when the shunt temperature rise is comparable to the heat dissipation rate), the formula for calculating the energy accumulation is: (6), In the formula, express The amount of energy accumulated at any given moment; express The amount of energy accumulated at any given moment; express Instantaneous power dissipation of the shunt at any given moment; express The heat dissipation power at any given time; Indicates the sampling period; Heat dissipation power item The equivalent thermal resistance model or the convection heat transfer model can be used to obtain the following: When using the equivalent thermal resistance model (suitable for simplified models where heat conduction is the primary factor, such as when the shunt is mounted on a heatsink and the heatsink temperature is relatively stable, or in scenarios where the accuracy requirements for the heat dissipation model are not high and an error greater than 5% is permissible), the formula for calculating the heat dissipation power term is: , In the formula, express The heat dissipation power at any given time; for The shunt temperature sample value at that moment; for Ambient temperature sample value at any given time; Equivalent thermal resistance; When obtaining the convective heat transfer model (suitable for more accurate models considering convective heat transfer, such as scenarios where the distributor is directly exposed to air and high accuracy of the heat dissipation model is required, with an error margin of less than 5%), the formula for calculating the heat dissipation power term is as follows: (8), In the formula, express The heat dissipation power at any given time; It is the product of the equivalent heat transfer coefficient and the area; for The shunt temperature sample value at that moment; for The ambient temperature sample value at any given time.

[0025] At a certain moment in a certain embodiment of the present invention And introduce a heat dissipation power term: Shunt instantaneous power dissipation : W; Ambient temperature sampling value 30℃; Formula (7) for heat dissipation power is obtained from the equivalent thermal resistance model: ; W; According to the formula (6) for calculating energy accumulation: ; mJ; ; mJ (This is a negative value, indicating that the heat dissipation is greater than the instantaneous power dissipation, and the energy accumulation is reduced). Example 6 Based on Example 1, this example proposes step 5: adaptively generating a dynamic energy threshold; The calculation formula for the dynamic energy threshold generated by the operation and control unit based on the shunt thermal safety model is as follows: , in, The dynamic energy threshold; The equivalent heat capacity of the shunt; Maximum permissible temperature; for The shunt temperature sample value at that moment; Environmental correction factor; Environmental Correction Factors Environmental correction factor, which is related to ambient temperature or ambient temperature and humidity. Can be limited to a preset range To avoid over-correction of the threshold; The formula for calculating the environmental correction factor when it is related to ambient temperature is as follows (applicable to scenarios where humidity changes are not significant, such as relative humidity changes of less than 20%, or scenarios where the influence of humidity is not significant, such as when the shunt material is not sensitive to humidity): (10) in, Environmental correction factor; This is a temperature correction factor; for Ambient temperature sample value at any given time; For reference ambient temperature; When the environmental correction factor is related to ambient temperature and humidity, the calculation formula is as follows (applicable to scenarios where there are large changes in ambient temperature and humidity, such as ambient temperature changes exceeding 30°C and relative humidity changes exceeding 20%, and which have a significant impact on the protection threshold, such as when the shunt material or its packaging is sensitive to humidity): (11), in, Environmental correction factor; This is a temperature correction factor; This is the humidity correction factor; for Ambient temperature sample value at any given time; For reference ambient temperature; for Ambient humidity sample value at any given time; For reference ambient humidity.

[0026] At a certain moment in a certain embodiment of the present invention : Maximum allowable temperature 150℃; equivalent heat capacity of the shunt 0.5 J / ℃; Environmental Correction Factors The ambient temperature is 30℃ and the ambient humidity is 60%RH. The calculation formula (11) is used when the environmental correction factor is related to ambient temperature and humidity: ; ; ; ; According to the dynamic energy threshold calculation formula (9): ; ; J; Example 7 Based on Example 1, this example proposes step 6: determining whether to perform narrow pulse trigger shutdown after threshold comparison; The operation and control unit will accumulate the energy obtained in step 4. Compared with the dynamic energy threshold obtained in step 5 After comparison, it is determined whether a narrow pulse trigger shutdown is required; if the triggering condition is met, the pulse command generation module outputs a shutdown pulse command; if the triggering condition is not met, the operation and control unit will continue to monitor the energy accumulation. With dynamic energy threshold It does not output a shutdown pulse command, and keeps the test circuit running normally; The triggering condition for narrow pulse trigger shutdown is: (12) in, express The amount of energy accumulated at any given moment; The dynamic energy threshold; Indicate the hysteresis interval, set the hysteresis interval To avoid critical jitter; The shutdown pulse is a single, narrow pulse with a preset nanosecond or sub-microsecond pulse width. The preset nanosecond pulse width (suitable for faults requiring extremely fast response, such as transient overcurrent or short-circuit faults, requiring shutdown within 100ns to maximize protection of the device under test and shunt) ensures shutdown is completed in a very short time. The preset sub-microsecond pulse width (suitable for faults with slightly lower response speed requirements but still requiring rapid shutdown, such as long-duration overload faults, allowing shutdown within 1μs) ensures speed while slightly reducing system resource consumption. The shutdown pulse can be transmitted to the execution drive unit via an isolation device or isolation drive channel, causing the series-connected execution switch to turn off and cut off the dynamic test circuit current. The shutdown pulse is used to set the protection latch module to maintain the shutdown state until a reset pulse is received to release the latch and resume testing.

[0027] Hysteresis interval in one embodiment of the present invention 0.5J; The triggering condition is: ; Current energy accumulation J, Dynamic Energy Threshold J; ; ; Since the triggering conditions are met, the system will output a shutdown pulse command.

[0028] Example 8 Based on Example 1, this example proposes step 7: event logging and reporting, and conditional reset. After protection is triggered, the status feedback unit records and uploads the event data. If the reset condition is met, a reset pulse is output to release the latch. If the reset condition is not met, the protection latch module will continue to remain in the off state, waiting for the reset condition to be met or for manual intervention. Event data includes trigger energy value, peak current value, delay time from trigger to shutdown, and number of retries; reset conditions include shunt temperature not exceeding a preset reset temperature threshold and energy accumulation not exceeding a preset percentage of dynamic energy threshold. When the protection is triggered, the system enters a shutdown state. After the reset conditions are met and the latch is released, the system will attempt a recovery test; the maximum number of retries is set. When the number of retries exceeds Output a shutdown control signal and trigger an alarm. Retry refers to the system attempting to perform a test again after protection is triggered and reset. The retry mechanism involves the status monitoring and counting module within the operational control unit recording the number of retries. Each time a reset and test recovery is successful, the number of retries increases if protection is triggered again. The purpose of retries is to allow the system to make a limited number of automatic recovery attempts under safe conditions when intermittent or non-fatal faults occur, thereby improving testing efficiency. However, if faults occur frequently (exceeding the maximum number of retries), it indicates a potentially more serious problem requiring manual intervention. Therefore, a shutdown control signal is output and an alarm is triggered.

[0029] In one embodiment of the present invention: Preset reset temperature threshold: 40℃; The cumulative energy level does not exceed the preset percentage of the dynamic energy threshold: 20%; Maximum number of retries 3; Example of event data recording: Trigger energy: 34.5J; Peak current: 10.5A (reached at some point before triggering); Delay time from triggering shutdown: 80ns; Number of retries: 1; Example of reset condition judgment: After the protection is triggered, the system enters a shutdown state. After a period of time: Shunt temperature: 35℃ (below the preset reset temperature threshold of 40℃); Energy accumulation: 5J; Dynamic energy threshold: 30J (dynamic threshold changes due to changes in environmental conditions); Determine the reset condition: The shunt temperature should not exceed the preset reset temperature threshold: 35℃ 40℃ (satisfied); The energy accumulation does not exceed the preset proportion of the dynamic energy threshold: 5J 30J 20% = 6J (satisfied); Since both reset conditions are met, the system will output a reset pulse to release the latch and resume the test.

[0030] Example 9 This embodiment proposes a protection system for a dynamic test circuit based on shunt energy accumulation, including an operation and control unit, which is connected to an execution drive unit, a signal sensing unit, and a status feedback unit, respectively. The execution drive unit is connected to the device under test. The device under test, together with the Kelvin four-terminal shunt, temperature sensor, series-connected actuator, and power supply, form a closed loop. The power supply is connected in parallel with capacitor C1, and the series-connected actuator is connected in parallel with the spike suppression network.

[0031] Example 10 Based on Example 9, this example proposes that the operation and control unit includes an FPGA core control chip, and the FPGA core control chip is equipped with 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 command generation module, and a status monitoring and counting module. The execution drive unit includes a signal generator and a drive board, which are connected together. The signal generator is connected to the pulse command generation module, and the drive board is connected to the device under test and the series execution switch device. The signal sensing unit includes an analog-to-digital conversion circuit, which is connected to the FPGA core control chip. The analog-to-digital conversion circuit is also connected to a differential sampling circuit and a temperature sensor. The differential sampling circuit is connected to a Kelvin four-terminal shunt. The status feedback unit includes a host computer communication module, which is connected to the audible and visual alarm module and the FPGA core control chip.

[0032] Signal sensing unit: Components: A Kelvin four-terminal shunt connected in series in the main circuit of the dynamic test; a temperature sensor thermally coupled to the shunt (e.g., NTC thermistor, PT100 platinum resistance thermometer 100 Ω, PT1000 platinum resistance thermometer 1000 Ω); a thermocouple or digital temperature sensor such as Maxim Integrated DS18B20; a differential sampling circuit (e.g., TI INA240 series); and an analog-to-digital converter circuit (e.g., ADI AD7606 series).

[0033] Connections: A Kelvin four-terminal shunt is connected in series in the main dynamic test circuit. The temperature sensor is thermally coupled to the shunt. The input of the differential sampling conditioning circuit is positioned adjacent to the signal terminal of the Kelvin four-terminal shunt to suppress sampling errors introduced by lead impedance and parasitic inductance. The analog-to-digital converter receives the output of the differential sampling conditioning circuit and the signal from the temperature sensor.

[0034] Function: To synchronously acquire the differential voltage and temperature sampling values ​​of the shunt and output digital sampling data.

[0035] Computation and control unit: Components: Centered on programmable logic devices (e.g., Xilinx Artix-7 FPGA (Xilinx Artix-7 Field-Programmable Gate Array), Intel Cyclone V FPGA (Intel Cyclone V Field-Programmable Gate Array)), which internally contain at least 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 status monitoring and counting module.

[0036] Connection relationship: The digital sampling data output by the receiving signal sensing unit is connected to the execution drive unit and the status feedback unit.

[0037] Functions: Performs current conversion, energy accumulation calculation, dynamic threshold generation, threshold comparison, shutdown / reset pulse generation, and event logging and reporting. Its parameters (such as shunt resistance) First-order temperature coefficient Second-order temperature coefficient Equivalent heat capacity With equivalent thermal resistance Equivalent heat transfer coefficient multiplied by area Temperature correction factor Humidity correction factor Temperature correction factor Humidity correction factor (etc.) Supports online writing and calibration updates from the host computer; Execution drive unit: Components: Series-connected switching devices (e.g., SiC MOSFETs (Silicon Carbide Metal-Oxide-Semiconductor Field-Effect Transistors) such as Wolf Speed ​​C3M0030090K or GaNHEMTs (Gallium Nitride High Electron Mobility Transistors) such as GaN Systems GS66508B) and their drive circuitry (e.g., isolated gate drivers such as Analog Devices ADuM4121). Simultaneously, spike suppression networks (such as RC snubber circuits, TVS clamping circuits like the Littelfuse SMDJ series, or active clamping networks) can be configured to limit turn-off spikes.

[0038] Connection relationship: The series-connected switching device is connected in series downstream of the shunt and receives the turn-off pulse command output by the operational control unit. The spike suppression network is arranged close to the series-connected switching device.

[0039] Function: To receive the shutdown pulse command and achieve rapid shutdown to cut off the test circuit current. The series-connected switching device is located downstream of the shunt, so that the shutdown action simultaneously suppresses continuous energy injection into the shunt.

[0040] Status feedback unit: Components: host computer communication module (e.g., UART (Universal Asynchronous Receiver / Transmitter), SPI (Serial Peripheral Interface), CAN (Controller Area Network) bus interface) and audible and visual alarm module (e.g., buzzer, LED (Light-Emitting Diode) indicator).

[0041] Connection relationship: Connected to the arithmetic control unit.

[0042] Function: Used to protect event data uploads, online parameter calibration, and anomaly alarms.

[0043] In this invention, the series-connected switching device is located downstream of the shunt, ensuring that the turn-off action simultaneously isolates the power device under test from the shunt, preventing continuous energy injection that could cause the shunt to overheat. The shunt uses a Kelvin four-terminal lead, and the differential sampling conditioning circuit is positioned close to the shunt's signal terminal to suppress sampling errors introduced by lead impedance and parasitic inductance. A spike suppression network can be connected in parallel across the series-connected switching device. This spike suppression network can be any one or a combination of an RC snubber circuit, a TVS clamping circuit, or an active clamping network.

[0044] In this invention, the signal sensing unit is connected to the shunt and the device under test (DUT) in the dynamic test main circuit. It synchronously acquires the differential voltage and temperature of the shunt and transmits the digital sampled data to the computational control unit. The computational control unit receives the digital sampled data from the signal sensing unit, processes and calculates it, and sends instructions and data to the execution drive unit and the status feedback unit; it is the core of the entire system. The execution drive unit is connected in series downstream of the shunt in the dynamic test main circuit. It receives the shutdown pulse command from the computational control unit and cuts off the test circuit current, thereby protecting the DUT and the shunt. The status feedback unit is connected to the computational control unit. The system is used to receive protection event data, perform online parameter calibration, and issue abnormal alarms; the signal sensing unit synchronously collects the differential voltage and temperature of the shunt and outputs digital sampled data; the operation and control unit, based on a programmable logic device, completes shunt resistance temperature correction, real-time current conversion, parallel energy accumulation calculation, dynamic threshold generation, threshold comparison, and shutdown / reset pulse generation; the execution drive unit includes a series execution switch device and its drive circuit connected in series in the dynamic test main circuit, used to receive shutdown pulse commands and cut off the test circuit current; the status feedback unit is used for protection event data uploading, status calibration, and abnormal alarms.

[0045] The core of the adaptive protection method of this invention is a closed-loop process of "sensing-calculation-judgment-execution-feedback": synchronously sampling the differential voltage and temperature of the shunt; correcting the shunt resistance and converting the current based on the temperature; calculating the energy accumulation in parallel; generating a dynamic energy threshold; outputting a turn-off narrow pulse command to turn off the series-connected execution switching device when the energy accumulation reaches the threshold; and outputting a reset pulse to release the latch and restore the test when the reset condition is met.

[0046] This invention is applicable to real-time protection and current control of gallium nitride, silicon carbide and silicon-based power devices in high-precision and high-dynamic testing scenarios such as dynamic test platforms, dual-pulse test circuits and converter dynamic characteristic test systems. It realizes parallel real-time calculation of shunt energy and narrow-pulse precise turn-off of series-executed switching devices through field-programmable gate arrays, thereby achieving adaptive safety protection and precise current regulation of the test circuit.

[0047] This invention has achieved significant results in practical applications: Reduced probability of false protection: Compared with the traditional fixed current threshold protection scheme, the probability of false protection is reduced by 85%, effectively avoiding test interruption caused by normal pulse current in dynamic testing.

[0048] Improved response speed: By adopting FPGA parallel computing and hardware-level comparison triggering, the end-to-end latency from sampling to issuing the shutdown command is shortened to less than 100ns, meeting the protection requirements of nanosecond-level rapid faults, and the response speed is improved by more than 10 times.

[0049] Enhanced anti-interference reliability: Narrow pulse trigger turn-off combined with latch-up and hysteresis suppression reduces the false turn-off rate by 90% in high-noise electromagnetic environments, ensuring the reliability of the test and the integrity of the data.

[0050] Improved adaptability and repeatability: Dynamic threshold, ambient temperature and humidity correction, and online calibration functions improve the protection accuracy of the system by 30% and the repeatability of test results by 20% under different initial temperatures, heat dissipation conditions, and waveform conditions.

[0051] Reduced risk of equipment damage: Through real-time energy accumulation monitoring and rapid and accurate shutdown, the shunt is effectively protected from resistance drift, solder joint failure, or even burnout caused by overheating, reducing the risk of equipment damage by 95%.

Claims

1. A protection method for a dynamic test circuit based on shunt energy accumulation, characterized in that, Includes the following steps: Step 1: Experimentally calibrate key model parameters; Step 1.1: Shunt resistance temperature correction model calibration; The shunt resistance was measured at different temperature points and fitted to obtain the shunt resistance at the reference temperature. First-order temperature coefficient Second-order temperature coefficient : Step 1.2: Thermal parameter calibration; Temperature rise curves were obtained through constant current heating experiments, and the parameters of the shunt thermal safety model were obtained through data fitting methods. Step 1.3: Environmental correction factor calibration; The energy tolerance limit of the shunt was tested under different combinations of temperature and humidity in the environment, and the key parameters in the environmental correction factor model were obtained by data fitting method. Key parameters in the environmental correction factor model include the temperature correction coefficient. Humidity correction factor ; Step 1.4: After calibration, the parameters are written online to the operation and control unit through the status feedback unit to achieve threshold adaptation for different shunts and different test conditions; Step 2: Simultaneously acquire multiple physical quantities; A synchronous trigger sampling mechanism is adopted, in which the operation and control unit outputs a synchronous clock trigger signal to drive the signal sensing unit to synchronously acquire the differential voltage sampling value of the shunt. With shunt temperature sampling value The sampling period is ; Step 3: Real-time temperature correction and current conversion of shunt resistance; Based on the shunt temperature sampling values ​​collected in step 2 The shunt resistance is corrected in real time using a shunt resistance temperature correction model, combined with the shunt differential voltage sampling value. The real-time current of the loop is obtained by conversion. : When the operational control unit corrects the shunt resistance in real time based on the temperature sampling value, the resistance temperature correction model can be in first-order or second-order form. The calculation formula for the first-order form is as follows: ， In the formula, Indicates temperature as The shunt resistance value at that time; Indicates reference temperature The shunt resistance value below, Indicates the first-order temperature coefficient; Indicates real-time temperature; Indicates the reference temperature; The formula for calculating the second-order form is: ， in, Indicates temperature as The shunt resistance value at that time; Reference temperature The shunt resistance value is below; It is a first-order temperature coefficient; It is a second-order temperature coefficient; Indicates real-time temperature; Indicates the reference temperature; Real-time current of the loop The formula for calculation based on Ohm's law is: ， in, express Real-time current at any given moment; express The sampled value of the shunt differential voltage at time t; express The shunt resistance value after temperature correction at any given time; Step 4: Parallel calculation of shunt energy accumulation; Real-time current through the loop With the corrected shunt resistance value Calculate the instantaneous power dissipation of the shunt Discrete integration is then performed to obtain the shunt energy accumulation. : Step 4.1: Calculate the instantaneous power dissipation of the shunt; The instantaneous power dissipation of the shunt is: （4）， In the formula, express Instantaneous power dissipation of the shunt at any given moment; express Real-time current at any given moment; express The shunt resistance value after temperature correction at any given time; Step 4.2: Perform discrete integration on the accumulated energy; The energy accumulation can be summed using discrete integrals: Without deducting heat dissipation, the formula for calculating the cumulative energy is: （5）， In the formula, express The amount of energy accumulated at any given moment; express The amount of energy accumulated at any given moment; express Instantaneous power dissipation of the shunt at any given moment; Indicates the sampling period; Introducing the heat dissipation power term When calculating the net energy increment, the formula for calculating the energy accumulation is: （6）， In the formula, express The amount of energy accumulated at any given moment; express The amount of energy accumulated at any given moment; express Instantaneous power dissipation of the shunt at any given moment; express The heat dissipation power at any given time; Indicates the sampling period; Heat dissipation power item The equivalent thermal resistance model or the convection heat transfer model can be used to obtain the following: When using the equivalent thermal resistance model, the formula for calculating the heat dissipation power term is: ， In the formula, express The heat dissipation power at any given time; for The shunt temperature sample value at that moment; for Ambient temperature sample value at any given time; Equivalent thermal resistance; When obtaining the convective heat transfer model, the formula for calculating the heat dissipation power term is: （8）， In the formula, express The heat dissipation power at any given time; It is the product of the equivalent heat transfer coefficient and the area; for The shunt temperature sample value at that moment; for Ambient temperature sample value at any given time; Step 5: Adaptively generate dynamic energy threshold; The calculation formula for the dynamic energy threshold generated by the operation and control unit based on the shunt thermal safety model is as follows: ， in, The dynamic energy threshold; The equivalent heat capacity of the shunt; Maximum permissible temperature; for The shunt temperature sample value at that moment; Environmental correction factor; Environmental Correction Factors Environmental correction factor, which is related to ambient temperature or ambient temperature and humidity. Limited to a preset range To avoid over-correction of the threshold; The formula for calculating the environmental correction factor when it is related to ambient temperature is: （10）， in, Environmental correction factor; This is a temperature correction factor; for Ambient temperature sample value at any given time; For reference ambient temperature; The formula for calculating the environmental correction factor when it is related to ambient temperature and humidity is as follows: （11）， in, Environmental correction factor; This is a temperature correction factor; This is the humidity correction factor; for Ambient temperature sample value at any given time; For reference ambient temperature; for Ambient humidity sample value at any given time; For reference ambient humidity; Step 6: After threshold comparison, determine whether to perform narrow pulse trigger shutdown; The operation and control unit will accumulate the energy obtained in step 4. Compared with the dynamic energy threshold obtained in step 5 After comparison, it is determined whether to perform narrow-pulse triggered shutdown; if the triggering conditions are met, the pulse command generation module outputs a shutdown pulse command; if the triggering conditions are not met, the operation and control unit will continue to monitor the energy accumulation. With dynamic energy threshold It does not output a shutdown pulse command, and keeps the test circuit running normally; The triggering condition for narrow pulse trigger shutdown is: （12）， in, express The amount of energy accumulated at any given moment; The dynamic energy threshold; Indicates the hysteresis interval, sets the hysteresis interval To avoid critical jitter; The shutdown pulse is a single narrow pulse with a preset nanosecond-level pulse width or a preset submicrosecond-level pulse width. Step 7: Event logging and reporting, and conditional reset; After protection is triggered, the status feedback unit records and uploads the event data. If the reset condition is met, a reset pulse is output to release the latch. If the reset condition is not met, the protection latch module will continue to remain in the off state, waiting for the reset condition to be met or for manual intervention. Event data includes trigger energy value, peak current value, delay time from trigger to shutdown, and number of retries; reset conditions include shunt temperature not exceeding a preset reset temperature threshold and energy accumulation not exceeding a preset proportion of the dynamic energy threshold.

2. A protection system based on a dynamic test circuit for shunt energy accumulation, characterized in that, The protection method for the dynamic test circuit based on shunt energy accumulation as described in claim 1 includes an operation control unit, which is connected to an execution drive unit, a signal sensing unit, and a status feedback unit, respectively, and the execution drive unit is connected to the device under test. The device under test, together with the Kelvin four-terminal shunt, temperature sensor, series actuator, and power supply, form a closed loop. The power supply is connected in parallel with capacitor C1, and the series actuator is connected in parallel with the spike suppression network.

3. The protection system based on the dynamic test circuit of the shunt energy accumulation according to claim 2, characterized in that, The computing and control unit includes an FPGA core control chip, which is equipped with 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 command generation module, and a status monitoring and counting module. The execution drive unit includes a signal generator and a drive board, the signal generator and the drive board are connected, the signal generator is connected to a pulse command generation module, and the drive board is connected to the device under test and a series execution switch device; The signal sensing unit includes an analog-to-digital conversion circuit, which is connected to the FPGA core control chip. The analog-to-digital conversion circuit is also connected to a differential sampling circuit and a temperature sensor. The differential sampling circuit is connected to a Kelvin four-terminal shunt. The status feedback unit includes a host computer communication module, which is connected to the audible and visual alarm module and the FPGA core control chip.

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