Sampling-resistor-free overcurrent protection system based on hardware protection

Abstract

The invention relates to the technical field of motor control and protection, and particularly discloses a non-sampling resistor overcurrent protection system based on hardware protection, which is characterized in that a current estimation value is generated after temperature compensation by monitoring the conduction voltage drop and temperature parameters of a power switch tube, a traditional sampling resistor is not needed, and power loss and heat generation are reduced; the system adopts a hardware security chip to carry out encrypted signature verification on current data, so that the authenticity and integrity of the data are ensured, and signal interference or hostile attack is prevented; meanwhile, the system can dynamically adjust an overcurrent protection threshold value according to the real-time rotating speed and historical load current of the motor, and the working condition adaptability is improved; when it is detected that the current rises at an extremely high rate, the system immediately triggers a protection action to effectively deal with sudden faults such as short circuit; and the execution module controls a power switch tube to be turned off through a hardware security chip, records a protection event log, and ensures reliable execution and afterwards tracing of a protection action.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motor control and protection, in particular to a sampling-free resistance overcurrent protection system based on hardware protection. BACKGROUND

[0002] The motor control system is the core component in the fields of modern industrial automation, new energy vehicles, smart home, etc., which realizes various complex mechanical movements by precisely controlling the speed, torque and position of the motor. In the motor drive system, overcurrent protection is a crucial basic function, which aims to prevent the permanent damage to the power switch tube, motor winding and even the whole system caused by excessive current due to abnormal conditions such as excessive load, motor stall or circuit short circuit. Therefore, designing an efficient, reliable and rapid overcurrent protection scheme is the key link in the design of all motor controllers.

[0003] In the prior art, the mainstream motor overcurrent protection scheme usually relies on a low-resistance, high-power current sampling resistor connected in series in the motor phase current path or DC bus loop. By detecting the voltage drop across the resistor, and through the amplification of the operational amplifier and the sampling of the analog-to-digital converter, the real-time current value can be converted according to Ohm's law. The control unit, such as a microcontroller, compares the measured current value with a fixed overcurrent threshold value preset in software or hardware. Once the current value exceeds the fixed threshold value, the control unit will immediately issue an instruction to turn off the gate signal of the driving power switch tube, thereby cutting off the current path and achieving protection.

[0004] However, the above prior art scheme has some inherent defects. First, the current sampling resistor itself as a power-consuming element will generate a considerable power loss and heat when a large current flows through it, which directly reduces the overall energy efficiency of the motor drive system and may require additional heat dissipation design. Second, it is difficult to meet the full operating requirements of the motor with a fixed overcurrent protection threshold value. In order to avoid false triggering during normal large current phases such as motor starting, the threshold value often needs to be set higher, but this will sacrifice the detection sensitivity to abnormal overcurrent during normal low-load operation. Finally, the traditional current detection signal link lacks effective security protection mechanisms and is easily affected by external electromagnetic interference or internal signal crosstalk, and even in the increasingly networked application scenarios, there is a risk of signal tampering by malicious attackers, which may lead to the failure of the protection function. SUMMARY

[0005] In view of this, in order to solve the problems raised in the background art, a sampling-free resistance overcurrent protection system based on hardware protection is proposed.

[0006] The purpose of the application can be achieved by the following technical solutions: The application provides a hardware protection-based non-sampling resistance overcurrent protection system, comprising: an initialization configuration module, which configures a digital key and parameters of an overcurrent protection algorithm to a hardware security chip through a secure programming interface, calibrates a temperature sensor and a conduction voltage drop monitoring circuit to generate a calibration coefficient, and sets an initial overcurrent protection threshold value based on rated parameters of a motor.

[0007] A current estimation value generation module monitors a conduction voltage drop of a power switch tube in a motor driving circuit, acquires a temperature parameter of a temperature sensor, performs temperature compensation calculation on the conduction voltage drop and the temperature parameter, and generates a current estimation value.

[0008] A current data security verification module performs digital signature verification on the current estimation value through a hardware security chip with a built-in digital key and overcurrent protection algorithm, and generates current data that passes verification.

[0009] An operating state parameter acquisition module acquires current operating state parameters of the motor, wherein the current operating state parameters include a rotating speed and load current historical data.

[0010] An adaptive overcurrent threshold value generation module dynamically adjusts the overcurrent protection threshold value based on the current data that passes verification and the current operating state parameters, and generates an adaptive overcurrent threshold value.

[0011] A protection decision signal generation module compares the current data that passes verification with the adaptive overcurrent threshold value, and generates a protection decision signal when the current data that passes verification exceeds the adaptive overcurrent threshold value.

[0012] A protection event log execution module controls the power switch tube to be turned off through the hardware security chip according to the protection decision signal, and records a protection event log.

[0013] Compared with the prior art, the embodiments of the application have at least the following advantages or beneficial effects: (1) The application eliminates the additional power loss and heating problem caused by the sampling resistance by omitting the traditional current sampling resistance and using the conduction voltage drop of the power switch tube for current estimation, which not only improves the energy utilization efficiency of the entire motor driving system and reduces the operating cost, but also helps to reduce the size of the circuit board and the hardware cost, making the design of the motor controller more compact and economical.

[0014] (2) The application innovatively introduces a hardware security chip as a trust root of the protection system to encrypt and sign the estimated current data and verify it. This design ensures the authenticity and integrity of the current data used for decision-making, effectively preventing the failure or misoperation of the protection function caused by signal interference, data errors or malicious attacks. At the same time, the shutdown instruction and event log are processed by the hardware security chip, ensuring the reliable execution of the protection action and the non-repudiation of the subsequent traceability, greatly improving the safety and reliability of the entire motor protection system.

[0015] (3) The application proposes a generation mechanism of adaptive overcurrent threshold, which can intelligently adjust the protection boundary according to the real-time speed and historical load current of the motor and other dynamic parameters. This makes the protection threshold no longer a fixed, compromised value, but can closely match the current working condition of the motor, providing sufficient margin to avoid unnecessary shutdown during motor startup or heavy load, and providing more sensitive protection during light load, thereby ensuring absolute safety while significantly enhancing the running stability and working condition adaptability of the system.

[0016] (4) The application identifies sudden serious faults such as short circuit by monitoring the instantaneous change rate of current. When the current rises at an extremely high rate, the system can bypass the conventional delay judgment logic and immediately trigger the protection action. This differentiated treatment strategy for slowly changing overcurrent and sudden short circuit enables the system to respond to the most dangerous working condition in the shortest time, providing more extreme and comprehensive safety protection for power devices and motor bodies. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0018] Figure 1 is a schematic diagram of the system module structure of the application. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only some embodiments of the application, not all embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0020] Please refer to Figure 1The application provides a hardware protection-based sampling-free resistance overcurrent protection system, which comprises an initialization configuration module, a current estimation value generation module, a current data security verification module, a running state parameter acquisition module, an adaptive overcurrent threshold value generation module, a protection decision signal generation module and a protection event log execution module.

[0021] The initialization configuration module is connected with the current estimation value generation module, the current estimation value generation module is connected with the current data security verification module, the initialization configuration module, the current data security verification module and the running state parameter acquisition module are all connected with the adaptive overcurrent threshold value generation module, the current data security verification module and the adaptive overcurrent threshold value generation module are both connected with the protection decision signal generation module, and the protection decision signal generation module is connected with the protection event log execution module.

[0022] The initialization configuration module configures a digital key and the parameters of an overcurrent protection algorithm to a hardware security chip through a secure programming interface, calibrates a temperature sensor and a conduction voltage drop monitoring circuit to generate a calibration coefficient, and sets an initial overcurrent protection threshold value based on motor rated parameters.

[0023] In the embodiment of the application, the specific steps that the calibration temperature sensor and the conduction voltage drop monitoring circuit generate the calibration coefficient and set the initial overcurrent protection threshold value based on the motor rated parameters include: injecting a standard temperature signal to the temperature sensor, acquiring a measurement value deviation to generate a temperature calibration coefficient.

[0024] A reference voltage is input to the conduction voltage drop monitoring circuit, an ADC reading deviation is acquired to generate a voltage drop calibration coefficient.

[0025] It should be noted that the initialization configuration module performs a series of precise preliminary preparations after the system is powered on or reset, providing accurate reference and initial safety boundary for the subsequent sampling-free resistance overcurrent protection function. First, the hardware calibration process is performed, which aims to eliminate inherent measurement errors caused by individual differences of components, manufacturing tolerances and environmental changes. The first step is the calibration of the temperature sensor. The operator or automated equipment applies a precise known temperature to the temperature sensor, which is the standard temperature signal. The system reads the output value of the temperature sensor at this time and compares it with the known standard temperature signal. The difference between the two is the measurement value deviation. The system calculates a correction value based on this deviation to generate a temperature calibration coefficient. The coefficient is stored for subsequent correction of real-time temperature readings to ensure the accuracy of the temperature parameter. The second step is the calibration of the on-state voltage drop monitoring circuit. The core of the circuit is the analog-to-digital converter ADC, which converts the analog on-state voltage drop of the power switch tube into a digital signal. During calibration, a high-precision, stable reference voltage source is connected to the input of the on-state voltage drop monitoring circuit. The system reads the digital output reading of the ADC and compares it with the ideal digital reading corresponding to the reference voltage. The difference between them is the ADC reading deviation. The system generates a voltage drop calibration coefficient based on this deviation, which is also stored to compensate and correct all subsequent measurements of the on-state voltage drop, ensuring high fidelity of the voltage data.

[0026] It should also be noted that the formula for generating the temperature calibration coefficient is: wherein, is the temperature calibration coefficient, is the proportional coefficient, is the temperature measurement value deviation, is the offset. The formula for generating the voltage drop calibration coefficient is: wherein, is the voltage drop calibration coefficient, is the ADC reading deviation, i.e. the voltage deviation, is the reference voltage.

[0027] It should be further noted that the values of the proportional coefficient and the offset are usually determined by experimental calibration method. In a laboratory environment, a set of known standard temperature signals are applied to the temperature sensor, and the output value of the sensor is recorded to calculate the actual deviation. The least squares method is used to fit the data to obtain the proportional coefficient and the offset wherein, the value range of is generally 0.9 to 1.1, the value range of

[0028] is generally -1℃ to +1℃.Read the motor pre-configured rated current value, peak overload multiple and safety margin coefficient from the non-volatile memory.

[0029] Multiply the motor pre-configured rated current value, peak overload multiple and safety margin coefficient to obtain the initial overcurrent protection threshold.

[0030] It should be noted that after completing the hardware calibration, the system enters the setting process of the initial overcurrent protection threshold. The initial overcurrent protection threshold is the initial static reference line of motor protection. The system will access the on-board non-volatile memory to read the pre-configured key rated parameters for a specific motor. These parameters include the motor pre-configured rated current value, which defines the maximum current of the motor under normal operating conditions for long-term stable operation; the peak overload multiple, which is a dimensionless coefficient, used to describe the maximum current impact that the motor can withstand for a short time under conditions such as starting or load mutation, which is a multiple of the rated current; and the safety margin coefficient, which is also a dimensionless coefficient, usually slightly larger than 1, aiming to provide an additional protection buffer to cope with unforeseen operating conditions or component aging. After obtaining these three key parameters, the system establishes an initial protection boundary that meets the motor design specifications and retains sufficient safety space by multiplying the three key parameters.

[0031] The embodiment of the application effectively eliminates the inherent measurement error at the hardware level by implementing accurate sensor and circuit calibration, providing a highly accurate data source for subsequent current estimation based on the on-state voltage drop. At the same time, by reading the specific rated parameters of the motor and combining the peak overload and safety margin coefficient to set the initial overcurrent protection threshold, the scientificity and pertinence of the protection reference are ensured. This comprehensive initialization configuration method lays a solid and reliable foundation for the entire non-sampling resistor overcurrent protection system, not only improving the accuracy of current estimation, but also enabling the initial protection strategy to closely match the actual physical characteristics and safety requirements of the driven motor, thereby establishing an effective safety line at the beginning of system startup.

[0032] The current estimation value generation module monitors the on-state voltage drop of the power switch tube in the motor drive circuit and obtains the temperature parameter of the temperature sensor, and performs temperature compensation calculation on the on-state voltage drop and the temperature parameter to generate a current estimation value.

[0033] In specific embodiments of the application, the specific steps of temperature compensation calculation on the on-state voltage drop and the temperature parameter to generate a current estimation value include: sampling the voltage value of the power switch tube in the on-state to obtain the original on-state voltage drop.

[0034] It should be noted that the core task of the current estimation value generation module is to accurately calculate the real-time current flowing through the motor winding without using the traditional sampling resistor. This process is completed by precise measurement and compensation of the physical characteristics of the power switch tube itself. First, the system monitors the state of the core element in the motor drive circuit, i.e. the power switch tube. When the main controller issues an instruction to make the power switch tube fully conductive, the on-state voltage drop monitoring circuit will immediately sample the voltage across it at high speed, thereby obtaining a voltage measurement value, which is the original on-state voltage drop. This value directly reflects the voltage drop of the power switch tube as a conductor under the current current.

[0035] The real-time temperature value of the temperature sensor is read to obtain a temperature parameter.

[0036] It should be noted that at the same time, the system synchronously reads real-time temperature data from the temperature sensor adjacent to or integrated near the power switch tube, which is defined as a temperature parameter, representing the current working junction temperature of the power switch tube or its closely related ambient temperature.

[0037] The original on-state voltage drop is compensated and calculated by combining the on-state resistance-temperature compensation curve with the calibration coefficient to output the compensated current estimation value as the current estimation value.

[0038] It should be noted that after obtaining the two original data of the original on-state voltage drop and the temperature parameter, the system enters the key temperature compensation calculation link. The on-state resistance of the power switch tube is not a constant value, but increases significantly with the increase of temperature, which is its inherent semiconductor physical characteristics. If temperature compensation is not performed, only the fixed on-state resistance value is used to calculate the current, which will produce a large error at different temperatures. Therefore, the system will use the calibration coefficient generated in the initialization configuration stage to first correct the original on-state voltage drop and the temperature parameter to obtain more accurate voltage and temperature values. Subsequently, the system queries an on-state resistance-temperature compensation curve pre-stored in the memory according to the corrected temperature parameter. The curve accurately describes the correspondence between the on-state resistance value and the temperature of the power switch tube of this model. By looking up the table, the system can obtain the actual on-state resistance value of the power switch tube at the current accurate temperature. Finally, the system applies the basic principle of Ohm's law to divide the corrected on-state voltage drop by the real-time on-state resistance value obtained by temperature compensation to calculate the compensated current estimation value, which is output as the final current estimation value.

[0039] It should also be noted that the specific formula for correcting the original on-state voltage drop and the temperature parameter to obtain more accurate voltage and temperature values is: wherein, is the corrected more accurate temperature value, is the original temperature value; wherein, Von is the corrected more accurate voltage, Von is the original on voltage drop.

[0040] The embodiment of the application ingeniously utilizes the on voltage drop characteristics of the power switch tube itself to realize current sensing, and completely eliminates the physical sampling resistor. This not only reduces the hardware cost of the system and the occupied space of the circuit board, but more importantly, it eliminates the additional power loss and heat generation caused by the sampling resistor itself, thereby improving the energy efficiency of the entire motor drive system. By introducing a precise temperature compensation mechanism, the method effectively overcomes the nonlinear influence of the on resistance of the power switch tube changing with temperature, ensuring that high-precision current estimation values can be obtained within a wide range of operating temperatures, providing a reliable and stable data foundation for subsequent overcurrent protection decisions.

[0041] The current data security verification module generates verified current data by verifying the current estimation value through a hardware security chip with a digital key and an overcurrent protection algorithm.

[0042] In specific embodiments of the application, the specific steps of generating verified current data include: using the digital key in the hardware security chip to calculate the hash message authentication code of the current estimation value to generate a digital signature.

[0043] The digital signature is verified to confirm data integrity.

[0044] When the data integrity check passes, the verified current data is output.

[0045] It should be noted that the function of the current data security verification module is to give the current data from the current estimation value generation module an unforgeable security certificate, to ensure its authenticity and integrity in the subsequent processing flow. The whole process takes a dedicated hardware security chip as the core, which is a microprocessor with a built-in encryption engine and can securely store keys. When the current estimation value generation module calculates a new current estimation value, the data is not directly used, but first sent to the hardware security chip. After the chip receives the current estimation value, it calls the digital key preloaded in its internal secure storage area, which is securely written during system initialization and cannot be read externally. Then, the encryption engine in the hardware security chip performs a hash message authentication code calculation. Hash Message Authentication Code (HMAC) is a key-based hash algorithm that can combine input data of any length, i.e. current estimation value and a secret digital key, to generate a fixed-length, unique authentication code, which is called digital signature in this system. After completing the signature generation, the system performs a verification step to confirm data integrity. This verification process means that the system confirms that the current current estimation value used for decision-making is indeed the original value just after the signature calculation, and that the signature is generated by the legitimate hardware security chip. When the hardware security chip confirms that the digital signature generated internally matches the input current estimation value correctly, the data integrity verification passes. At this time, the current estimation value is considered to be trusted, and the module outputs it as verified current data for subsequent key function safety such as adaptive overcurrent threshold generation module and protection decision signal generation module.

[0046] The encryption verification process based on the hardware security chip establishes a solid security barrier for the data link of the non-sampling resistance overcurrent protection system. It ensures that each current data point used for protection decision-making has undergone strict identity authentication and integrity check. This mechanism can effectively resist spoofing attacks on sensor signals or data errors caused by system failure, and prevent protection function failure or false triggering caused by using fake or damaged current data. By establishing the root of trust on the physically difficult-to-attack hardware security chip, the security and reliability of the entire protection system are greatly improved, ensuring that the overcurrent protection decision is always based on real and trusted current state, thereby providing more robust and reliable security for the motor.

[0047] The running state parameter acquisition module acquires the current running state parameter of the motor, wherein the current running state parameter includes the rotation speed and the load current historical data.

[0048] It should be noted that the current operating state parameters of the motor are usually directly collected by the sensor module integrated in the motor driver or control system, wherein the rotation speed data is generally obtained by an encoder or a Hall sensor, and the load current data is monitored in real time by a current sampling resistor in the driving circuit, a Hall current sensor or a current detection unit built in the power module. After the physical signals are converted into electrical signals by these sensors, the microcontroller or data acquisition system records and stores them as historical data.

[0049] The adaptive overcurrent threshold generation module dynamically adjusts the overcurrent protection threshold based on the verified current data and the current operating state parameters to generate an adaptive overcurrent threshold.

[0050] In specific embodiments of the present application, the specific steps of dynamically adjusting the overcurrent protection threshold to generate an adaptive overcurrent threshold include analyzing the load current historical data in the current operating state parameters to calculate an average current value.

[0051] In specific embodiments of the present application, the specific steps of analyzing the load current historical data in the current operating state parameters to calculate an average current value include obtaining the verified current data in the recent period of time in a sliding window manner to form a current value sequence.

[0052] It should be noted that this method describes in detail how to accurately calculate the average current value representing the recent load condition of the motor from a series of continuous but possibly noisy current data. This process is designed as a three-step fine data processing procedure. The first step is data collection. The system uses a sliding window to capture the latest dynamic information. It maintains a fixed-size data buffer and continuously fills the latest verified current data into the window while discarding the oldest data. In this way, a dynamically updated current value sequence is formed, which always reflects the working current condition of the motor in the recent period of time.

[0053] The current value sequence is subjected to median filtering to remove outliers to generate a filtered sequence.

[0054] It is noted that the second step is data purification, i.e. median filtering of the acquired current value sequence. In the actual operation of the motor, due to electromagnetic interference or load mutation, the current signal may be mixed with some transient, amplitude abnormal spike pulses, which are called outliers. If the sequence containing outliers is directly averaged, a result deviating from the actual load level will be obtained. Median filtering is a nonlinear signal processing technique that sorts the data within the window and selects the value at the middle position as the output of the current point. This method can extremely effectively filter out isolated outliers without blurring the step edges of the signal as traditional mean filtering does. After median filtering, the system obtains a more smooth and real filtered sequence that eliminates burr interference.

[0055] The moving average of the filtered sequence is calculated to obtain the average current value.

[0056] It is noted that the third step is the final mean calculation. The system calculates the moving average of the purified filtered sequence. The moving average is calculated by adding all the values in the filtered sequence and dividing by the length of the sequence, i.e. the size of the sliding window. This calculation result is finally determined as the average current value and output to the adaptive overcurrent threshold generation module. The calculation can be expressed as: wherein, represents the final output average current value; is the total number of data points in the sliding window; represents the current data point in the filtered sequence; the symbol indicates the summation of all current data points from the first point to the

[0057] The threshold reference value is adjusted based on the average current value, the sensitivity coefficient and the initial overcurrent protection threshold.

[0058] It is noted that after obtaining the average current value, the system enters the stage of generating the threshold reference value. This step is a dynamic adjustment based on the initial overcurrent protection threshold. The initial overcurrent protection threshold is a static upper limit set during system initialization, while the threshold reference value is an intermediate variable that has been preliminarily adjusted according to the actual load of the motor. The adjustment process combines the average current value and a key parameter, i.e. the sensitivity coefficient. The sensitivity coefficient is a pre-set dimensionless value that determines the response sensitivity of the threshold reference value to changes in the average current value. The adjustment process can be expressed by the following formula: wherein, represents the calculated threshold reference value; is the initial overcurrent protection threshold set during the system configuration stage;​​ is a sensitivity coefficient, which controls the magnitude of the increase of the protection threshold with the increase of the load.

[0059] In one embodiment of the present application, the sensitivity coefficient is a pre-set dimensionless parameter, and its typical value is usually 1.0, which is based on the requirement of dynamic balance between the threshold reference value and the average current value in engineering practice. When the sensitivity coefficient is 1.0, the threshold reference value will have a linear response relationship of 1:1 with the change of the average current value, which can effectively capture current fluctuations to trigger the protection mechanism, and can also avoid the response delay caused by too small coefficient or false action caused by too large coefficient. This setting has been widely verified as the optimal solution that balances stability and sensitivity in scenarios such as motor control and power management that require accurate overcurrent protection.

[0060] The generated threshold reference value is corrected in combination with the speed parameter in the current operating state parameter, and an adaptive overcurrent threshold is output.

[0061] It should be noted that, however, adjustment based only on the average current is not enough to fully adapt to the complex dynamic characteristics of the motor. Therefore, the module further introduces the speed parameter in the current operating state parameter to finally correct the threshold reference value. The overcurrent characteristics of the motor differ at different speeds, for example, the allowed short-time current at low speed or locked-rotor state can be much higher than at high speed. The system will obtain a correction factor corresponding to the current speed by looking up the pre-set speed-threshold correction factor curve according to the real-time obtained speed parameter. Multiplying this correction factor by the threshold reference value will finally obtain the adaptive overcurrent threshold, which is output to the protection decision signal generation module.

[0062] The embodiment of the present application realizes a fundamental change of the protection strategy from static to adaptive by dynamically adjusting the overcurrent protection threshold. Compared with the fixed protection threshold, this method can make the protection boundary closely fit the actual operating load and speed of the motor, thereby achieving a double optimization effect. On the one hand, when the motor is lightly loaded, the adaptively reduced threshold can provide more sensitive fault detection capability to timely discover potential abnormal overcurrent. On the other hand, when the motor is heavily loaded or in normal operating conditions requiring high peak current such as starting, the adaptively increased threshold can effectively avoid false alarms and unnecessary shutdowns caused by normal current fluctuations, significantly enhancing the operating stability and tolerance to operating condition changes of the system, and finally realizing a safe and efficient intelligent motor protection.

[0063] The protection decision signal generation module compares the verified current data with the adaptive overcurrent threshold, and generates a protection decision signal when the verified current data exceeds the adaptive overcurrent threshold.

[0064] In the embodiments of the present application, the specific step of generating the protection decision signal when the verified current data exceeds the adaptive overcurrent threshold comprises: continuously monitoring the verified current data.

[0065] In the embodiments of the present application, the specific step of continuously monitoring the verified current data comprises: performing differential calculation on the verified current data to generate an instantaneous change rate.

[0066] It should be noted that this method adds a fast response channel in the continuous monitoring process of the protection decision signal generation module to deal with sudden serious overcurrent events such as motor stall or inter-phase short circuit. The core of this fast channel is to monitor the current change rate. While performing amplitude comparison on the verified current data, the system performs differential calculation on it in parallel. Differential calculation is to subtract the current data point of the immediately preceding sampling period from the current data point, and then divide by the time interval of the sampling period, thereby obtaining the instantaneous change rate of the current.

[0067] Compare the generated instantaneous change rate with the gradient threshold.

[0068] When the instantaneous change rate exceeds the gradient threshold, bypass the delay period and accelerate the triggering of the overcurrent event flag.

[0069] It should be noted that after calculating the instantaneous change rate, the system will immediately compare it with the preset gradient threshold. The gradient threshold is an upper limit of the current change rate set according to the motor characteristics and system safety requirements. It defines what degree of rapid increase of current should be considered as an emergency fault signal. The current rise rate caused by normal motor starting or load change should be lower than this gradient threshold. When the system detects that the calculated instantaneous change rate exceeds the preset gradient threshold, a special fast response logic will be triggered. In this case, the system judges that the current occurrence is an extremely dangerous and needs to be responded immediately serious overcurrent event. Therefore, it will directly bypass the aforementioned standard delay period judgment process and no longer wait for whether the current over-limit state will last for a period of time. Instead, it will immediately and without delay trigger the overcurrent event flag. This accelerated triggered overcurrent event flag will then enter the subsequent priority judgment link, and usually this kind of event triggered by gradient overrun will be given the highest processing priority, thereby ensuring that the protection decision signal can be generated quickly.

[0070] In one embodiment of the application, the typical value of the gradient threshold can be set as 50 A / ms, which is based on the safety specification of motor control system and practical engineering experience: when the rate of change of motor winding current exceeds this value, it may cause risks such as core saturation, winding overheating or inverter module damage, while 50 A / ms can effectively identify the emergency failure of rapid current growth, and can avoid false triggering caused by normal start-stop or load fluctuation. This value is widely used as a critical standard for triggering protection mechanism in the safety design of permanent magnet motor active short-circuit protection and power electronic equipment.

[0071] When the verified current data exceeds the adaptive overcurrent threshold and lasts for a delay period, the overcurrent event flag is triggered.

[0072] It should be noted that the protection decision signal generation module is the judgment center of the entire overcurrent protection system, and its core task is to make a final decision on whether to execute protection action at the right time based on real-time data and dynamic threshold. This process begins with continuous monitoring of verified current data flow. The module continuously compares each newly received, security-verified current data point with the current adaptive overcurrent threshold output by the adaptive overcurrent threshold generation module. When the system detects that the verified current data first exceeds the adaptive overcurrent threshold, it does not immediately trigger protection, but starts an internal timer and enters an observation phase called the delay period. The delay period is set to filter out short-duration current spikes caused by load transient fluctuations or electrical noise, which do not represent a real and sustained overcurrent fault. During the entire delay period, the system continuously checks whether the subsequent current data is still higher than the adaptive overcurrent threshold. Only when this over-limit state has been continuously uninterrupted since the beginning and has lasted for the entire preset delay period, the system will confirm that it is an effective overcurrent event. At this time, a specific state register, i.e. the overcurrent event flag, will be set in the system.

[0073] The overcurrent event flag is prioritized in combination with the motor operating mode parameters obtained from the main controller to generate a protection decision signal.

[0074] It needs to be explained that after triggering the overcurrent event flag, the system enters a more delicate decision-making stage. It will request the current motor operating mode parameter from the host controller or read it from the shared memory. The motor operating mode parameter describes the state in which the motor is currently operating, for example, it may be normal constant speed operation, acceleration start, deceleration braking or diagnostic mode, etc. The module combines the triggered overcurrent event flag with the obtained motor operating mode parameter to make a priority judgment. This judgment logic is based on pre-set rules, for example, during the motor start-up phase, a short-term large current is allowed to exist, so the priority of the overcurrent event flag processing may be lower or different coping strategies are adopted; while in the stable rated speed running state, any sustained overcurrent should be considered as a high priority risk. According to the result of this priority judgment, the module finally decides whether to generate an explicit protection instruction, i.e. outputs the protection decision signal, to start the subsequent physical protection action.

[0075] The embodiment of the application greatly enhances the anti-interference ability and decision robustness of the overcurrent protection system by introducing a delay cycle mechanism, effectively avoids false protection caused by transient noise or normal transient current fluctuation, thereby ensuring the continuity of the motor drive system. Further, by combining the motor operating mode parameter for priority judgment, the protection decision is no longer a single and rigid threshold comparison, but is transformed into an intelligent and context-aware decision closely related to the actual working condition of the motor. This intelligent judgment logic ensures that the protection system can intervene decisively when it is really needed, and remains tolerant when the motor is in a special but allowed working condition, achieving a high balance between safety and availability, and significantly improving the intelligent level and operation reliability of the entire system.

[0076] The protection event log execution module controls the power switch tube to be turned off through the hardware security chip according to the protection decision signal, and records the protection event log.

[0077] In specific embodiments of the application, the specific steps of controlling the power switch tube to be turned off through the hardware security chip and recording the protection event log include extracting the verified current data, adaptive overcurrent threshold and current operating state parameter at the protection triggering time to form a log data unit.

[0078] It is to be noted that the protection event log execution module is responsible for executing the critical physical shutdown action and safely recording the event scene information after the overcurrent protection is triggered. When the module receives the explicit protection decision signal sent by the protection decision signal generation module, the first task is to immediately send an instruction to the motor drive circuit through the hardware security chip to forcibly and quickly turn off all related power switches. By directly controlling the shutdown path with the hardware security chip, the execution of the instruction has high priority and high reliability, bypassing the possible delay or failure of the conventional software control link. At the same time of executing the shutdown action, the system immediately starts the log recording program to freeze and save the key state information at the moment of fault occurrence. First, the module accurately extracts multiple core data items at the protection triggering time from the system data bus or related registers. This includes the specific verification passed current data that triggered this protection, i.e. the peak or trigger value of the fault current; the adaptive overcurrent threshold at that time, which reflects the basis for the protection system to make a judgment; and the current operating state parameters including the speed and load current history data. These three groups of data are integrated together to form a structured log data unit, which completely reproduces the scene at the time of fault occurrence.

[0079] The log data unit is marked with a trusted timestamp and encrypted using a hardware security chip to generate an encrypted log.

[0080] It is to be noted that subsequently, in order to ensure the non-repudiation and confidentiality of the log, this log data unit is sent to the hardware security chip for secure processing. The hardware security chip uses its built-in secure clock or acquires time from a trusted time source to mark the log data unit with a trusted timestamp. This timestamp accurately records the absolute time of the protection event occurrence, and since it is generated by a secure hardware, its authenticity is guaranteed. Next, the hardware security chip calls the digital key pre-stored in the internal secure storage area to perform an encryption algorithm such as AES on the timestamped log data unit, converting it into a piece of ciphertext that cannot be directly interpreted, i.e. generating an encrypted log.

[0081] The encrypted log is stored in a non-volatile memory.

[0082] It is to be noted that the last step is the persistent storage of the log. The system writes the encrypted log generated by the hardware security chip into the on-board non-volatile memory. The non-volatile memory can still retain data without loss after the system is powered off. By storing the encrypted log in this way, the system ensures that even after the device is powered off and restarted, this critical protection event record can still be completely preserved for subsequent fault diagnosis, responsibility tracing or system performance analysis.

[0083] The embodiment of the application realizes highly safe and reliable event response by deeply integrating the hardware security chip into the protection execution and log recording process. The hardware directly controls the shutdown, ensuring the immediacy and certainty of the protection action. Meanwhile, by extracting the key failure data, applying a trusted timestamp and performing encryption processing, a protection event log system that is anti-tampering and anti-forgery is constructed. This approach not only provides extremely valuable, high-fidelity first-hand data for post-analysis, but also greatly enhances the security audit capability and diagnostic accuracy of the system, providing a solid data foundation for improving product reliability maintenance and long-term performance optimization.

[0084] The above is merely an example and description of the concept of the application, and those skilled in the art can make various modifications or supplements to the described specific embodiments or replace them with similar ways, as long as they do not deviate from the concept of the application or exceed the scope defined by the application.

Claims

1. A hardware-based overcurrent protection system without sampling resistor, characterized in that, include: The initialization configuration module configures the digital key and overcurrent protection algorithm parameters to the hardware security chip through the secure programming interface, calibrates the temperature sensor and conduction voltage drop monitoring circuit to generate calibration coefficients, and sets the initial overcurrent protection threshold based on the motor's rated parameters. The current estimation generation module monitors the on-state voltage drop of the power switch in the motor drive circuit and obtains the temperature parameters from the temperature sensor. It then performs temperature compensation calculations on the on-state voltage drop and temperature parameters to generate a current estimate. The current data security verification module uses a hardware security chip with a built-in digital key and overcurrent protection algorithm to perform digital signature verification on the current estimate and generate verified current data. The operating status parameter acquisition module acquires the current operating status parameters of the motor, which include historical data of speed and load current. The adaptive overcurrent threshold generation module dynamically adjusts the overcurrent protection threshold based on verified current data and current operating status parameters to generate an adaptive overcurrent threshold. The protection decision signal generation module compares the verified current data with the adaptive overcurrent threshold. When the verified current data exceeds the adaptive overcurrent threshold, it generates a protection decision signal. The protection event log execution module controls the power switch to turn off via the hardware security chip based on the protection decision signal, and records the protection event log.

2. The hardware-based overcurrent protection system without sampling resistor according to claim 1, characterized in that: The specific steps for calibrating the temperature sensor and conduction voltage drop monitoring circuit to generate calibration coefficients and setting the initial overcurrent protection threshold based on the motor's rated parameters include: A standard temperature signal is injected into the temperature sensor, and the measurement deviation is obtained to generate a temperature calibration coefficient; The reference voltage is input to the conduction voltage drop monitoring circuit to obtain the ADC reading deviation and generate a voltage drop calibration coefficient. Read the motor's pre-configured rated current, peak overload multiple, and safety margin factor from the non-volatile memory; The initial overcurrent protection threshold is obtained by multiplying the pre-configured rated current value, peak overload multiple, and safety margin factor of the motor.

3. The hardware-based overcurrent protection system without sampling resistor according to claim 2, characterized in that: The specific steps for performing temperature compensation calculations on the on-state voltage drop and temperature parameters to generate current estimates include: The voltage value of the sampled power switch in the on-state is used to obtain the original on-state voltage drop; Read the real-time temperature value from the temperature sensor to obtain the temperature parameters; By combining the calibration coefficient with the on-resistance-temperature compensation curve, the original on-voltage drop is compensated and calculated, and the compensated current estimate is output as the current estimate.

4. The hardware-based overcurrent protection system without sampling resistor according to claim 1, characterized in that: The specific steps for generating the verified current data include: The digital key within the hardware security chip is used to calculate the hash message authentication code for the current estimate, generating a digital signature. Verify digital signatures to confirm data integrity; When the data integrity verification passes, the verified current data is output.

5. The hardware-based overcurrent protection system without sampling resistor according to claim 2, characterized in that: The specific steps for dynamically adjusting the overcurrent protection threshold and generating an adaptive overcurrent threshold include: Analyze the historical load current data in the current operating status parameters to calculate the average current value; Based on the average current value, sensitivity coefficient, and initial overcurrent protection threshold, adjust and generate the threshold reference value; The generated threshold reference value is corrected by combining the speed parameter in the current operating status parameters, and an adaptive overcurrent threshold is output.

6. The hardware-based overcurrent protection system without sampling resistor according to claim 5, characterized in that: The specific steps for analyzing historical load current data in the current operating status parameters and calculating the average current value include: A sliding window method is used to obtain the current data that has passed verification in the most recent period of time, forming a current value sequence; The current value sequence is subjected to median filtering to remove outliers, resulting in a filtered sequence. Calculate the moving average of the filtered sequence to obtain the average current value.

7. The hardware-based overcurrent protection system without sampling resistor according to claim 1, characterized in that: The specific steps for generating a protection decision signal when the verified current data exceeds the adaptive overcurrent threshold include: Continuously monitor and verify the current data; When the verified current data exceeds the adaptive overcurrent threshold and persists for one delay period, the overcurrent event flag is triggered. The overcurrent event flag is prioritized based on the motor operating mode parameters obtained from the main controller, and a protection decision signal is generated.

8. The hardware-based overcurrent protection system without sampling resistor according to claim 7, characterized in that: The specific steps for continuously monitoring and verifying the current data include: Differential calculations are performed on the verified current data to generate the instantaneous rate of change; Compare the generated instantaneous rate of change with the gradient threshold; When the instantaneous rate of change exceeds the gradient threshold, the delay period is bypassed, and the overcurrent event flag is triggered more quickly.

9. The hardware-based overcurrent protection system without sampling resistor according to claim 1, characterized in that: The specific steps of controlling the power switch transistor to turn off via a hardware security chip and recording the protection event log include: Extract the verified current data, adaptive overcurrent threshold, and current operating status parameters at the protection trigger moment to form a log data unit; The log data units are timestamped and encrypted using a hardware security chip to generate encrypted logs. Storing encrypted logs in non-volatile memory.

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