A new energy vehicle overload protector action hysteresis compensation control method and system

Abstract

The present application relates to the technical field of overload protector, and more particularly to a new energy vehicle overload protector action hysteresis compensation control method and system, which comprises obtaining real-time operating parameters of a target electric circuit, the real-time operating parameters at least including circuit current and temperature of a power device; based on the real-time operating parameters and their change trend, respectively calculating dynamic current risk threshold and dynamic temperature risk threshold; comparing the circuit current with the dynamic current risk threshold; comparing the temperature of the power device and the highest temperature within the inherent action hysteresis time of the overload protector predicted based on a preset thermal model with the dynamic temperature risk threshold; based on at least one comparison result, generating a graded intervention instruction in the case that potential overload risk exists and physical protection response will appear lag. Through the present application, the action hysteresis of the overload protector can be effectively compensated, and timely protection can be realized.

Description

Technical Field

[0001] This invention relates to the technical field of overload protectors, and in particular to a method and system for compensating for the hysteresis of an overload protector in a new energy vehicle. Background Technology

[0002] In the high-voltage electrical systems of new energy vehicles, overload protectors are used to disconnect faulty circuits in the event of short circuits or severe overloads, preventing permanent damage to critical components such as power devices due to overheating or overcurrent. Currently, common overload protection schemes mainly rely on comparing the real-time detected circuit current or device temperature with a preset fixed operating threshold; once the threshold is exceeded, the protector is triggered.

[0003] However, overload protectors inherently suffer from hysteresis, including sensor signal processing time, control logic computation time, and the physical breaking time of the protector's mechanical structure. When a fault manifests as a sharp rise in current or a rapid increase in temperature, even if the detected value has reached a fixed threshold, there is still a significant time window between issuing the command and the protector effectively completing its breaking action. Within this hysteresis window, fault current and heat may continue to accumulate, easily causing sensitive power semiconductor devices to exceed their safe operating range and be damaged before the actual protection action occurs. Existing methods using fixed-threshold protection logic cannot fundamentally compensate for the protection blind spot caused by this physical hysteresis.

[0004] Therefore, there is an urgent need for a control method that can effectively compensate for the lag in the action of overload protectors, so as to achieve timely protection and improve the safety of high-voltage electrical systems. Summary of the Invention

[0005] This invention provides a method and system for compensating for the hysteresis of an overload protector in new energy vehicles, which can effectively solve the problems in the background art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for compensating for the hysteresis of an overload protector in a new energy vehicle includes:

[0008] Obtain the real-time operating parameters of the target electrical circuit, wherein the real-time operating parameters include at least the circuit current and the temperature of the power devices;

[0009] Based on the real-time operating parameters and their changing trends, the dynamic current risk threshold and the dynamic temperature risk threshold are calculated respectively.

[0010] The loop current is compared with the dynamic current risk threshold; the temperature of the power device and the highest temperature predicted based on a preset thermal model during the inherent hysteresis time of the overload protector are compared with the dynamic temperature risk threshold.

[0011] Based on at least one comparison result, if it is determined that there is a potential overload risk and the physical protection response will be delayed, a graded intervention instruction is generated.

[0012] Furthermore, the dynamic current risk threshold is configured to be lower than the physical current action threshold of the overload protector, and decreases as the rate of change of the loop current increases;

[0013] The dynamic temperature risk threshold is configured to be lower than the upper limit of the safe operating temperature of the power device, and is adjusted based on the preset thermal model of the power device, the current temperature, and the historical load current.

[0014] Furthermore, the tiered intervention instructions include:

[0015] The first intervention command is used to suppress the output power of the electrical circuit;

[0016] The second intervention command is used to trigger the disconnection action of the overload protector in advance.

[0017] Furthermore, based on at least one comparison result, if it is determined that there is a potential overload risk and the physical protection response will be delayed, a graded intervention instruction is generated, including:

[0018] If the loop current reaches or exceeds the dynamic current risk threshold, and the corresponding current change rate does not exceed the first preset threshold, then the first intervention instruction is generated.

[0019] If the loop current does not reach the dynamic current risk threshold, and the real-time monitored temperature and / or the highest temperature exceeds the dynamic temperature risk threshold, then the first intervention command and the second intervention command are generated.

[0020] Furthermore, the execution of the first intervention command and the second intervention command are configured to be coordinated in timing, such that the suppression action on the output power precedes or is at least synchronized with the start time of the disconnection action of the overload protector.

[0021] Furthermore, the timing of issuing the second intervention command is determined by comparing and compensating for the inherent hysteresis time of the overload protector with the estimated time required for the fault to develop to the physical current action threshold.

[0022] Furthermore, the real-time operating parameters also include the DC bus voltage.

[0023] Furthermore, the dynamic current risk threshold is calculated, including:

[0024] Calculate the real-time sag rate of the DC bus voltage;

[0025] The dynamic current risk threshold is corrected based on the real-time drop rate, wherein the larger the real-time drop rate, the greater the downward correction of the dynamic current risk threshold.

[0026] Furthermore, the dynamic current risk threshold decreases as the rate of change of the loop current increases, including:

[0027] The overload protector is pre-calibrated through testing, and multiple current change rate gradient intervals are divided based on the inherent hysteresis time of the overload protector and the current withstand characteristics of the power device.

[0028] For each gradient interval, a corresponding dynamic current risk threshold reduction ratio is set;

[0029] Based on the gradient range to which the current change rate belongs, calculated in real time, the dynamic current risk threshold is adjusted according to the corresponding reduction ratio.

[0030] On the other hand, the present invention also provides a hysteresis compensation control system for overload protectors of new energy vehicles, comprising:

[0031] The parameter acquisition module is used to acquire the real-time operating parameters of the target electrical circuit, which include at least the circuit current and the temperature of the power devices;

[0032] The dynamic threshold calculation module is used to calculate the dynamic current risk threshold and the dynamic temperature risk threshold based on the real-time operating parameters and their changing trends, respectively.

[0033] The status judgment module is used to compare the loop current with the dynamic current risk threshold, and compare the temperature of the power device and the highest temperature predicted based on the preset thermal model during the inherent hysteresis time of the overload protector with the dynamic temperature risk threshold.

[0034] The instruction generation module is used to generate graded intervention instructions based on at least one comparison result of the state judgment module when it is determined that there is a potential overload risk and the physical protection response will be delayed.

[0035] The technical solution of this invention can achieve the following technical effects: By combining real-time operating parameters with changing trends to generate dynamic current and temperature risk thresholds, and by incorporating the real-time monitored temperature of the power device and the predicted maximum temperature during the hysteresis period into the comparison with the dynamic temperature risk threshold, the problem that fixed thresholds cannot adapt to the dynamic development of faults and are difficult to cover the physical hysteresis time window can be solved. The generation of dynamic thresholds allows the judgment criteria to be flexibly adjusted according to the speed of fault development, while the hysteresis temperature prediction takes into account the heat accumulation that may occur in the power device during the process from the issuance of the command to the actual disconnection of the protector. This control of real-time risks and potential future risks fills the protection gap caused by physical hysteresis and avoids the situation where the threshold is met but the protection action is not completed before the device is damaged.

[0036] The hierarchical intervention logic works in conjunction with the preceding judgment mechanism to ensure timely protection while taking into account the continuity of system operation. In existing technologies, simply adjusting a fixed threshold can easily lead to over- or under-protection. However, in this method, the generation of hierarchical intervention instructions is entirely based on the results of dynamic threshold comparison and hysteresis risk prediction. Only when a potential overload risk is confirmed and the physical protection response will lag, will intervention measures of corresponding strength be taken according to the actual risk situation, effectively avoiding unnecessary frequent protection and achieving a balance between security and system operation continuity.

[0037] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a flowchart illustrating the hysteresis compensation control method for overload protectors of new energy vehicles according to the present invention. Detailed Implementation

[0040] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0042] like Figure 1 As shown, the present invention provides a method for compensating for the hysteresis of an overload protector in a new energy vehicle, which specifically includes the following steps:

[0043] Step S100: Obtain the real-time operating parameters of the target electrical circuit, wherein the real-time operating parameters include at least the circuit current and the temperature of the power devices;

[0044] Step S200: Based on the real-time operating parameters and their changing trends, calculate the dynamic current risk threshold and the dynamic temperature risk threshold respectively;

[0045] Step S300: Compare the loop current with the dynamic current risk threshold; compare the temperature of the power device and the highest temperature predicted based on the preset thermal model during the inherent hysteresis time of the overload protector with the dynamic temperature risk threshold.

[0046] Based on at least one of the above comparison results, if it is determined that there is a potential overload risk and the physical protection response will be delayed, a graded intervention instruction is generated.

[0047] In this embodiment, real-time operating parameters and changing trends are combined to generate dynamic current and temperature risk thresholds. At the same time, the real-time monitored temperature of the power device and the predicted maximum temperature during the hysteresis period are both included in the comparison with the dynamic temperature risk threshold. This can solve the problem that fixed thresholds cannot adapt to the dynamic development of faults and are difficult to cover the physical hysteresis time window. The generation of dynamic thresholds allows the judgment criteria to be flexibly adjusted according to the speed of fault development, while the hysteresis temperature prediction takes into account the heat accumulation that may occur in the power device during the process from the issuance of the command to the actual disconnection of the protector. This control of real-time risks and potential future risks makes up for the protection gap caused by physical hysteresis and avoids the situation where the threshold is met but the device is damaged before the protection action is completed.

[0048] The hierarchical intervention logic works in conjunction with the preceding judgment mechanism to ensure timely protection while taking into account the continuity of system operation. In existing technologies, simply adjusting a fixed threshold can easily lead to over- or under-protection. However, in this method, the generation of hierarchical intervention instructions is entirely based on the results of dynamic threshold comparison and hysteresis risk prediction. Only when a potential overload risk is confirmed and the physical protection response will lag, will intervention measures of corresponding strength be taken according to the actual risk situation, effectively avoiding unnecessary frequent protection and achieving a balance between security and system operation continuity.

[0049] In some embodiments of the present invention, for step S100, a scheme for obtaining real-time operating parameters of the target electrical circuit is provided, specifically implemented as follows:

[0050] Step S110: Select a through-hole Hall element as the current acquisition element, and mount it on the outside of the busbar of the target electrical circuit, ensuring that the sensing surface of the element is perpendicular to the current direction of the busbar. The output terminal of the element is connected to the signal processing unit through a shielded cable. Select thin-film temperature sensing elements to form an acquisition array, and attach them to the exposed chip surface of the power device and the bonding surface of the heat dissipation substrate respectively through ceramic adhesive. The signal output terminal of each temperature sensing element is also connected to the same signal processing unit through a shielded cable.

[0051] Step S120: Set a unified reference sampling clock. The signal processing unit sends a collection trigger signal to the Hall element and the temperature sensing array simultaneously according to the reference clock cycle. After receiving the signal, the two types of elements start the data acquisition operation synchronously. After the acquisition is completed, the current analog signal and the temperature analog signal are transmitted to the signal processing unit synchronously. During the transmission process, the same timestamp is added to each group of data.

[0052] Step S130: The signal processing unit continuously analyzes the collected current data and calculates the current change per unit time. At the same time, it analyzes the temperature data and calculates the temperature change per unit time. When the current change exceeds the preset range or the temperature change exceeds the preset interval, the signal processing unit shortens the reference sampling clock cycle to increase the sampling frequency. When both the current change and the temperature change are within the preset stable range, the signal processing unit extends the reference sampling clock cycle to reduce the sampling frequency. The sampling frequency adjustment range is controlled between 5kHz and 20kHz.

[0053] Step S140: The signal processing unit performs zero-point offset calibration on the received current analog signal, uses a finite impulse response filtering algorithm to filter out harmonic interference, and converts it into a digital signal; it performs arithmetic average calculation on the temperature analog signal based on the multi-point acquisition values ​​to eliminate local deviations in contact measurement, and converts it into a digital signal; the processed current digital signal and temperature digital signal are stored in timestamp order.

[0054] In this embodiment, synchronous acquisition operations triggered by the same clock ensure that the loop current and power device temperature data have consistent timestamps, guaranteeing the correlation between the two types of parameters in the time dimension. The sampling frequency is dynamically adjusted according to the parameter changes. The frequency is increased when the parameter changes rapidly under fault conditions to ensure the capture of parameter change details, and decreased under stable conditions to reduce redundant data generation and reduce the computational load of the signal processing unit. Zero-point calibration and harmonic filtering of the current signal, and multi-point averaging processing of the temperature signal effectively reduce measurement interference deviation. The arrangement of the through-hole Hall element and the attached temperature sensing array ensures that the measurement signal directly reflects the true state of the target parameter, and the use of shielded cables reduces the impact of external electromagnetic interference on signal transmission.

[0055] In a specific implementation, as one example, the existing method pre-sets and keeps the protection threshold unchanged, which cannot respond to the rate of change of the loop current. When the current rises rapidly under fault conditions, the fixed threshold cannot reserve protection action time in advance and cannot compensate for the inherent hysteresis of the overload protector. At the same time, the temperature threshold is not related to the heat accumulation characteristics of the power device, and is only set according to the real-time temperature, ignoring the continuous impact of historical load current on the device temperature, resulting in a disconnect between temperature risk judgment and the actual heating state of the device. In order to address the above problems, this embodiment provides a specific implementation of the dynamic risk threshold calculation.

[0056] The dynamic current risk threshold is calculated as follows:

[0057] Step S211: Obtain the physical current operating threshold of the overload protector. This threshold is the rated operating current calibrated at the factory of the overload protector. Set 80% of this physical current operating threshold as the benchmark value of the dynamic current risk threshold.

[0058] Step S212: Extract the current data stored in step S100 in real time, calculate the rate of change of current in adjacent sampling periods according to the timestamp order, and obtain the rate of change of current by dividing the current difference between two adjacent sampling periods by the sampling period duration. The sampling period duration is determined by the sampling frequency in step S100.

[0059] Step S213: Based on the inherent hysteresis time of the overload protector and the current withstand characteristics of the power device, divide the current change rate into three gradient intervals. The boundary values ​​of each interval are calibrated by test to ensure that the gradient division can cover all current change scenarios from stable operating conditions to sudden faults.

[0060] Step S214: Set the threshold reduction ratio for each gradient. The reduction ratio is determined through experiments to ensure that it matches the inherent action hysteresis time of the overload protector: The first gradient interval corresponds to the scenario of gradual current change, and the reference value remains unchanged; the second gradient interval corresponds to the scenario of rapid current change, and the threshold is reduced by a fixed ratio of the reference value; the third gradient interval corresponds to the scenario of rapid current change, and the threshold is reduced by a higher fixed ratio of the reference value.

[0061] Step S215: Define a minimum value for the dynamic current risk threshold. This minimum value shall not be lower than 50% of the physical current operating threshold of the overload protector. If the result calculated according to the above ratio is lower than the minimum value, then the minimum value shall be used as the dynamic current risk threshold.

[0062] The dynamic temperature risk threshold is calculated as follows:

[0063] Step S221: Obtain the upper limit of the safe operating temperature of the power device. This upper limit is the calibration value in the power device's factory technical manual. Set 90% of this upper limit of the safe operating temperature as the initial value of the dynamic temperature risk threshold.

[0064] Step S222: Call the preset thermal model. This model is built based on the thermal resistance, thermal capacity and heat dissipation coefficient of the power device. The above parameters are all inherent thermal parameters calibrated by the power device at the factory. The model is used to characterize the relationship between load current and device temperature change.

[0065] Step S223: Extract the historical load current data stored in step S100. The historical data is selected from the current values ​​within multiple consecutive sampling periods. The number of sampling periods is determined by experiments to ensure that it can cover the critical period of heat accumulation of power devices. Substitute the current values ​​of each sampling period into the preset thermal model to calculate the temperature increment corresponding to each period. After accumulation, the total temperature increment within the period is obtained.

[0066] Step S224: Obtain the latest temperature data from step S100 in real time as the current temperature, add the current temperature to the total temperature increment, and obtain the temperature reference value corresponding to the actual heat accumulation of the device.

[0067] Step S225, the dynamic temperature risk threshold adjustment rule is as follows: when the difference between the temperature reference value and the upper limit of the safe operating temperature is within the first preset range, the initial value remains unchanged; when the difference between the temperature reference value and the upper limit of the safe operating temperature is within the second preset range, the initial value is reduced by a fixed proportion corresponding to the difference; the adjusted dynamic temperature risk threshold shall not be lower than 70% of the upper limit of the safe operating temperature. If the result calculated according to the above rule is lower than the lower limit, the lower limit shall be used as the dynamic temperature risk threshold; the above first preset range, second preset range and corresponding reduction proportion are all calibrated by test to ensure that they are compatible with the thermal accumulation characteristics of the power device and the inherent action hysteresis time of the overload protector.

[0068] In this embodiment, the gradient division and proportional adjustment of the dynamic current risk threshold are both calibrated through experiments. When the current rises rapidly under fault conditions, the threshold is reduced according to a clear rule, triggering subsequent intervention actions in advance. Sufficient response time is reserved for the inherent action hysteresis of the overload protector, ensuring that the current does not exceed the device's safe tolerance range before the physical protection action is completed. The dynamic temperature risk threshold accurately reflects the actual heat accumulation state of the power device by integrating the historical load current and current temperature over a continuous period through a preset thermal model based on the device's inherent thermal parameters, avoiding misjudgment of temperature risk caused by relying solely on real-time temperature.

[0069] More specifically, the pre-defined thermal model is constructed and implemented as follows:

[0070] The preset thermal model is constructed based on the transient thermal balance equation. Its logic is that the temperature change of the power device is determined by the difference between the heat generation power and the heat dissipation power. That is, the temperature increment of the device is equal to the ratio of the net heat absorbed per unit time to the heat capacity of the device. The net heat is the Joule heat generated by the load current minus the heat dissipated through the heat dissipation path.

[0071] The input variables of the preset thermal model include load current, current device temperature, ambient temperature, and sampling period duration. The load current and current temperature are obtained from the synchronous acquisition results of step S100, and the ambient temperature is acquired by a temperature sensing element attached to the device's heat dissipation system. The sampling period duration is consistent with the sampling frequency of step S100. The output variable is the temperature increment of the power device within a single sampling period, which is used for the subsequent accumulation calculation of the total temperature increment.

[0072] The parameters involved in the preset thermal analysis are all physical quantities that can be obtained through public channels or experimentally calibrated, specifically including:

[0073] Device on-resistance: An inherent parameter specified in the manufacturer's technical datasheet for power devices, characterizing the resistance value when the device is turned on;

[0074] Device thermal resistance: An inherent parameter specified in the manufacturer's technical datasheet for power devices, characterizing the thermal conduction resistance from the device chip to the heat dissipation substrate;

[0075] Device thermal capacity: An inherent parameter specified in the manufacturer's technical datasheet for power devices, characterizing the device's ability to absorb heat and cause its temperature to rise;

[0076] Heat dissipation coefficient: obtained through experimental calibration. Specifically, under known ambient temperature and load current conditions, the device temperature change is continuously monitored, and the coefficient is determined by backfitting based on the deviation between the actual temperature increment and the theoretical calculation value. The calibration process needs to cover the device's commonly used operating temperature range and load current range.

[0077] The steps for constructing the preset thermal model are as follows: Calculate the Joule heat generated by the load current within a single sampling period. This heat is obtained by multiplying the square of the load current, the device's on-resistance, and the sampling period duration. Calculate the heat dissipation of the device within a single sampling period. This heat is obtained by multiplying the difference between the device's current temperature and the ambient temperature, the heat dissipation coefficient, and the sampling period duration. The heat dissipation path includes heat conduction within the device itself and conduction through the heat dissipation substrate. Calculate the net heat within a single sampling period, i.e., the difference between Joule heat and heat dissipation. A positive net heat value indicates a temperature increase, while a negative value indicates a temperature decrease. Calculate the temperature increment within a single sampling period, obtained by the ratio of net heat to the device's heat capacity. A positive increment indicates a temperature increase, while a negative increment indicates a temperature decrease.

[0078] Furthermore, the implementation method for dividing the current change rate gradient interval and calibrating the boundary values ​​in step S213 is as follows:

[0079] Step S2131: Obtain the inherent hysteresis time of the overload protector and the current withstand characteristics of the power device to provide a quantitative basis for test calibration. Specifically, when measuring the inherent hysteresis time of the overload protector, a test circuit is set up to simulate overload conditions and trigger the protector's action. A high-speed data acquisition device records the time interval from the controller issuing the disconnect command to the complete separation of the protector contacts. This measurement is repeated 10 times and the average value is taken. The measurement process excludes the influence of external factors such as power fluctuations and electromagnetic interference. When determining the current withstand characteristics of the power device, its manufacturer's technical manual is consulted to obtain the maximum allowable current through the device at different durations. The maximum current increment that will prevent permanent damage to the device within the inherent hysteresis time of the overload protector is determined. This increment is the difference between the allowable current at the end of the hysteresis time and the current normal operating current.

[0080] Step S2132: Set up a test calibration platform. The test platform includes a target electrical circuit simulation unit, an overload protector test unit, power device samples, a collaborative sensing unit, and a data recording unit. The collaborative sensing unit is the same as the acquisition unit in step S100. The target electrical circuit simulation unit can output current rise signals with different slopes, covering the current change range from stable operation to sudden short circuit. The collaborative sensing unit synchronously acquires real-time current data during the test at the same sampling frequency as in step S100. The data recording unit stores the current data and corresponding device status feedback according to the timestamp.

[0081] Step S2133: Set multiple test conditions with the current rise rate gradually adjusted from low to high. Each test condition is repeated 3 times. In each test, the current signal with the set slope is output through the electrical circuit simulation unit. The time it takes for the current to rise from the normal operating value to the maximum allowable current of the power device is recorded synchronously. Combined with the inherent action hysteresis time of the overload protector, it is determined whether relying solely on a fixed threshold at this current change rate will cause the device to exceed the safe tolerance range during the hysteresis period. At the same time, the current change rate data and feedback information on whether the device has abnormal states such as overheating or performance degradation are collected under each test condition.

[0082] Step S2134: Determine the boundary values ​​of the gradient intervals based on experimental data. The upper boundary of the first gradient interval is the maximum value of the current change rate in experimental data where the current change rate is slow and the time for the current to rise to the device's maximum allowable current within the hysteresis period is greater than twice the hysteresis period. This interval is where the current change rate does not exceed the upper boundary. Within this interval, the current change is gradual, and triggering protection according to the benchmark value can ensure the device's safety within the hysteresis period. The lower boundary of the second gradient interval is the upper boundary of the first gradient interval. The upper boundary is the maximum value of the current change rate in experimental data where the current change rate is moderate and the time for the current to rise to the device's maximum allowable current within the hysteresis period is between 1 and 2 times the hysteresis period. Within this interval, the current change is relatively rapid, and the threshold needs to be appropriately reduced to reserve intervention time. The third gradient interval is the range where the current change rate exceeds the upper boundary of the second gradient interval. Within this interval, the current change is rapid, and the device's tolerance range is very likely to be exceeded within the hysteresis period. The threshold needs to be significantly reduced to trigger intervention in advance.

[0083] In some embodiments of the present invention, a graded intervention strategy is designed for step S300. Through time-series coordination and hysteresis compensation calculation, the intervention action is ensured to accurately adapt to the risk level and the inherent hysteresis of the protector. The specific implementation method is as follows:

[0084] Step S310: Extract the loop current and real-time monitoring temperature of the power device synchronously acquired in step S100, retrieve the dynamic current risk threshold and dynamic temperature risk threshold calculated in step S200; directly compare the loop current with the dynamic current risk threshold and record the comparison result.

[0085] The highest temperature during the inherent hysteresis time of the overload protector is predicted based on a preset thermal model. The prediction process is as follows: starting from the current real-time monitoring temperature, and combining the historical load current and the current current change trend in step S100, the temperature increment of each sampling cycle during the hysteresis time is calculated through the preset thermal model. All increments are accumulated to obtain the predicted temperature value at the end of the hysteresis time. This predicted value is the highest temperature during the hysteresis time. The real-time monitoring temperature and the highest temperature are compared with the dynamic temperature risk threshold, and the two comparison results are recorded.

[0086] Step S320: Predefine a first preset threshold. The first preset threshold is the upper boundary value of the first gradient interval in step S213, which is consistent with the calibration result of the current change rate gradient interval.

[0087] If the loop current reaches or exceeds the dynamic current risk threshold, and the corresponding current change rate does not exceed the first preset threshold, it is judged as a slight overload risk, and only the first intervention command is generated. The first intervention command sends a signal to the power control unit of the electrical circuit to reduce the output power by a fixed ratio. The reduction ratio is calibrated by test to ensure that the current can quickly fall back to below the dynamic current risk threshold.

[0088] If the loop current does not reach the dynamic current risk threshold, but the real-time monitored temperature and / or the highest temperature exceeds the dynamic temperature risk threshold, it is determined to be a temperature accumulation type overload risk, and the physical protection response may be delayed. At the same time, a first intervention command and a second intervention command are generated. The second intervention command triggers the disconnection action by sending a signal to the control terminal of the overload protector.

[0089] As a preferred embodiment of the above, the execution of the first intervention command and the second intervention command are configured to be coordinated in timing, such that the suppression action on the output power precedes or is at least synchronized with the start time of the disconnection action of the overload protector, as specifically implemented as follows:

[0090] A timing test loop is constructed, with a configuration consistent with the target electrical loop. This loop includes a power control unit, an overload protector, a collaborative sensing unit, and a high-speed timing device. The timing accuracy must meet microsecond-level measurement requirements. A first intervention command is sent to the power control unit, and the time interval from the command issuance to the electrical loop output power decreasing to a set proportion is recorded as the power suppression response time. This measurement is repeated 10 times, and the average value is taken. The measurement process covers different initial power levels and eliminates the influence of electromagnetic interference. A second intervention command is sent to the overload protector control terminal, and the time interval from the command issuance to the protector's tripping mechanism starting to operate is recorded as the tripping action start time. This measurement is repeated 10 times, and the average value is taken, ensuring consistency with the inherent action hysteresis time measurement conditions of the overload protector.

[0091] Based on the measured timing parameters of the two types of actions, a time difference is set between the first intervention command and the second intervention command. The time difference is calculated as the difference between the power suppression response time and the interruption action start time. If the difference is positive, the first intervention command is sent before the difference, ensuring that the power suppression action starts before the interruption action. If the difference is zero or negative, the first intervention command and the second intervention command are sent synchronously. At this time, the power suppression action and the interruption action start at the same time, satisfying the timing coordination requirements. For different power levels and temperature conditions, the above time parameter measurement and time difference calculation are repeated to establish a timing parameter reference table and store it in the control unit for actual operation and adaptation.

[0092] A simulation test platform was built to reproduce the temperature-accumulated overload risk condition, corresponding to the scenario where two commands are generated simultaneously. Commands were sent according to the set timing control rules. The power suppression action process and the timing of the protector's tripping mechanism action were recorded by a high-speed camera. Circuit current, power, and device temperature data were collected simultaneously. If the tripping action started before the power suppression action, the advance sending time of the first intervention command was adjusted to increase the time difference, and the test was repeated. If the advance sending time of the power suppression action was too long, causing excessive drop in circuit power and affecting stability, the advance sending time was appropriately shortened until the power suppression action started before the tripping action or both started simultaneously, and the circuit power was within a safe range at the moment of tripping. For the scenario where only the first intervention command is generated for mild overload risk, the stability of the power suppression response time was verified separately to ensure that the current quickly drops below the dynamic current risk threshold after the command is executed, without delay or over-suppression issues.

[0093] The control unit monitors the actual response timing of the two types of actions in real time. It uses the power change data and protector status data fed back by the collaborative sensing unit to determine whether there is a timing deviation. If the disconnection action is detected to start before the power suppression action, the timing parameters are corrected by extending the advance transmission time of the first intervention command. If the power suppression is detected to cause the circuit to stop, the advance transmission time is shortened and the corrected parameters are updated to the timing parameter reference table.

[0094] More specifically, the timing of issuing the second intervention command is determined by comparing and compensating for the inherent hysteresis time of the overload protector with the estimated time required for the fault to develop into a physical danger point, as follows:

[0095] The inherent hysteresis time of the overload protector is obtained according to the test method described above, directly calling the stored average measurement value to ensure that the measurement conditions are consistent with the actual operating conditions. The estimated time required for the fault to develop to the physical danger point is calculated separately according to the fault type. For current-type faults, i.e., the loop current is close to the dynamic current risk threshold and the rate of change is high, the estimated time is obtained by dividing the difference between the current loop current and the device's maximum allowable current by the current rate of change. The device's maximum allowable current is taken from the manufacturer's technical manual. For temperature-type faults, i.e., the temperature exceeds the dynamic temperature risk threshold, the estimated time is obtained by dividing the difference between the upper limit of the power device's safe operating temperature and the current temperature reference value by the temperature prediction increment per unit time. The temperature prediction increment per unit time is calculated by a preset thermal model. The estimated time calculation for both types of faults retains the average value of multiple sets of sampled data to reduce the impact of instantaneous fluctuations.

[0096] The inherent action lag time is calculated by comparing it with the estimated time for the fault to develop to the physical danger point. A rule for issuing commands corresponding to the comparison result is established: if the estimated time is greater than or equal to the inherent action lag time, the existing lag time is sufficient to complete the interruption action, and the second intervention command is issued at the current moment; if the estimated time is less than the inherent action lag time, the lag time is insufficient, and a command needs to be issued earlier to compensate for the time difference. The compensation time is the difference between the inherent action lag time and the estimated time, and the second intervention command is issued at the current moment after this compensation time. For different fault development rates, the above calculation is repeated to establish a compensation time comparison table, which is labeled with the corresponding compensation parameters based on the fault type and stored in the control unit for real-time retrieval. Simultaneously, for combined current and temperature fault scenarios, the minimum estimated time of the two types of faults is taken as the comparison benchmark to ensure that the compensation calculation adapts to the most dangerous fault development trend.

[0097] In a specific implementation, as one example, the correction of the dynamic current risk threshold is achieved by introducing DC bus voltage parameters and their real-time sag rate to realize accurate threshold adaptation, as detailed below:

[0098] Voltage sensing elements are arranged at both ends of the DC bus of the target electrical circuit and integrated with the collaborative sensing unit in step S100. The bus voltage data is collected synchronously at the same sampling frequency to ensure that the timestamps of voltage, current and temperature data are consistent. The real-time drop rate is obtained by dividing the difference between the bus voltage of two adjacent sampling cycles by the sampling cycle duration. The voltage difference is the positive result of the voltage value of the previous cycle and the voltage value of the current cycle, which only represents the drop amplitude. If the voltage is rising or stable, the drop rate is recorded as zero and the correction logic is not activated.

[0099] Based on the fault type and severity, and combined with the inherent hysteresis time of the overload protector, voltage drop rate gradient intervals are divided through experiments. The boundary values ​​of each interval are calibrated by simulating different short-circuit conditions, covering voltage change scenarios from minor overload to sudden short circuit. A corresponding threshold downward correction range is set for each gradient. The correction range is determined through experiments to ensure that it matches the fault severity. The greater the drop rate, the greater the correction range increases synchronously with the gradient, adapting to the protection needs of rapid fault development.

[0100] First, calculate the initial dynamic current risk threshold based on the current change rate according to steps S211 to S214. Then, call the real-time voltage drop rate and the corresponding correction magnitude to correct the initial threshold downward. For the combined operating condition of current change rate and voltage drop rate, establish correction priority. When the two correspond to different correction magnitudes, take the larger correction magnitude to ensure that it is adapted to the most severe fault manifestation.

[0101] The corrected dynamic current risk threshold shall not be lower than 50% of the physical current action threshold of the overload protector, and shall be consistent with the lower limit of the threshold in step S215. If the threshold after correction according to the voltage drop rate is lower than the lower limit, the lower limit shall be used as the final threshold to prevent the threshold from being too low, which would lead to frequent intervention and affect the stability of system operation.

[0102] In this embodiment, the voltage sag rate can predict short-circuit faults in advance, capturing fault characteristics faster than a single current parameter, providing a pre-signal for threshold correction, and adapting to the rapid response requirements of sudden faults; the composite parameter correction logic enables the dynamic current risk threshold to adapt to both current changes and voltage sag states, and the corrected threshold is more in line with the actual fault intensity, avoiding correction deviations caused by a single parameter.

[0103] Based on the same inventive concept as the overload protector action hysteresis compensation control method for new energy vehicles described in the foregoing embodiments, this invention also provides an overload protector action hysteresis compensation control system for new energy vehicles, the system comprising:

[0104] The parameter acquisition module is used to acquire the real-time operating parameters of the target electrical circuit, which include at least the circuit current and the temperature of the power devices;

[0105] The dynamic threshold calculation module is used to calculate the dynamic current risk threshold and the dynamic temperature risk threshold based on the real-time operating parameters and their changing trends, respectively.

[0106] The status judgment module is used to compare the loop current with the dynamic current risk threshold, and compare the temperature of the power device and the highest temperature predicted based on the preset thermal model during the inherent hysteresis time of the overload protector with the dynamic temperature risk threshold.

[0107] The instruction generation module is used to generate graded intervention instructions based on at least one comparison result of the state judgment module when it is determined that there is a potential overload risk and the physical protection response will be delayed.

[0108] The system described above in this invention can effectively implement a method for compensating for the action hysteresis of an overload protector in a new energy vehicle. The technical effects it can achieve are as described in the above embodiments, and will not be repeated here.

[0109] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of this application. Accordingly, this specification and drawings are merely exemplary illustrations of the application as defined herein, and are to be considered as covering any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from its scope. Thus, if such modifications and modifications fall within the scope of this application and its equivalents, this application intends to include such modifications and modifications.

Claims

1. A method for compensating for the hysteresis of an overload protector in a new energy vehicle, characterized in that, The method includes: Obtain the real-time operating parameters of the target electrical circuit, wherein the real-time operating parameters include at least the circuit current and the temperature of the power devices; Based on the real-time operating parameters and their changing trends, the dynamic current risk threshold and the dynamic temperature risk threshold are calculated respectively. The loop current is compared with the dynamic current risk threshold; the temperature of the power device and the highest temperature predicted based on a preset thermal model during the inherent hysteresis time of the overload protector are compared with the dynamic temperature risk threshold. Based on at least one comparison result, if it is determined that there is a potential overload risk and the physical protection response will be delayed, a graded intervention instruction is generated, including: a first intervention instruction for suppressing the output power of the electrical circuit, and a second intervention instruction for prematurely triggering the overload protector to disconnect. Methods for generating tiered intervention instructions include: If the loop current reaches or exceeds the dynamic current risk threshold, and the corresponding current change rate does not exceed the first preset threshold, then the first intervention instruction is generated. If the loop current does not reach the dynamic current risk threshold, and the real-time monitored temperature and / or the highest temperature exceeds the dynamic temperature risk threshold, then the first intervention command and the second intervention command are generated. The execution of the first intervention command and the second intervention command is configured to be coordinated in timing, such that the suppression of output power precedes or is at least synchronized with the start time of the disconnection action of the overload protector.

2. The method for compensating for hysteresis in overload protectors of new energy vehicles according to claim 1, characterized in that, The dynamic current risk threshold is configured to be lower than the physical current action threshold of the overload protector and decreases as the rate of change of the loop current increases. The dynamic temperature risk threshold is configured to be lower than the upper limit of the safe operating temperature of the power device, and is adjusted based on the preset thermal model of the power device, the current temperature, and the historical load current.

3. The method for compensating for hysteresis in overload protectors of new energy vehicles according to claim 1, characterized in that, The timing of the second intervention command is determined by comparing and compensating for the inherent hysteresis time of the overload protector with the estimated time required for the fault to develop to the physical current action threshold.

4. The method for compensating for hysteresis in overload protectors of new energy vehicles according to claim 1, characterized in that, The real-time operating parameters also include the DC bus voltage.

5. The method for compensating for hysteresis in the overload protector of a new energy vehicle according to claim 4, characterized in that, Calculating the dynamic current risk threshold includes: Calculate the real-time sag rate of the DC bus voltage; The dynamic current risk threshold is corrected based on the real-time drop rate, wherein the larger the real-time drop rate, the greater the downward correction of the dynamic current risk threshold.

6. The method for compensating for hysteresis in overload protectors of new energy vehicles according to claim 2, characterized in that, The dynamic current risk threshold decreases as the rate of change of loop current increases, including: The overload protector is pre-calibrated through testing, and multiple current change rate gradient intervals are divided based on the inherent hysteresis time of the overload protector and the current withstand characteristics of the power device. For each gradient interval, a corresponding dynamic current risk threshold reduction ratio is set; Based on the gradient range to which the current change rate belongs, calculated in real time, the dynamic current risk threshold is adjusted according to the corresponding reduction ratio.

7. A hysteresis compensation control system for an overload protector in a new energy vehicle, wherein the system is applied to the hysteresis compensation control method for an overload protector in a new energy vehicle as described in claim 1, characterized in that, The system includes: The parameter acquisition module is used to acquire the real-time operating parameters of the target electrical circuit, which include at least the circuit current and the temperature of the power devices; The dynamic threshold calculation module is used to calculate the dynamic current risk threshold and the dynamic temperature risk threshold based on the real-time operating parameters and their changing trends, respectively. The status judgment module is used to compare the loop current with the dynamic current risk threshold, and compare the temperature of the power device and the highest temperature predicted based on the preset thermal model during the inherent hysteresis time of the overload protector with the dynamic temperature risk threshold. The instruction generation module is used to generate graded intervention instructions based on at least one comparison result of the state judgment module when it is determined that there is a potential overload risk and the physical protection response will be delayed.

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