MOS transistor safety protection system based on overcurrent feedback and control method thereof

Abstract

The application discloses a MOS tube safety protection system based on overcurrent feedback and a control method thereof, and belongs to the technical field of electronic circuit protection. The system comprises multiple modules, which are respectively: a current sampling module obtains a source current through a manganese copper resistance of four-terminal connection; a signal conditioning module amplifies a sampling signal and filters high-frequency interference; a feedback control module converts the signal into a digital quantity, and determines an overcurrent level according to multiple overcurrent threshold values; a driving cutoff module lowers a MOS tube gate voltage through a high-speed optocoupler to realize rapid shutdown; a self-recovery module sets a delay reset according to the overcurrent level, and records a continuous overcurrent frequency; and a fault diagnosis module collects and uploads fault data. In addition, threshold value online adjustment is realized through a temperature load coupling correction unit, and early intervention is realized by using a current change rate prediction. The application is helpful to improve overcurrent detection precision, response speed and environmental adaptability, and can provide comprehensive safety protection for MOS tubes.

Description

Technical Field

[0001] This invention relates to the field of electronic circuit protection technology, specifically to a MOSFET safety protection system and its control method based on overcurrent feedback. Background Technology

[0002] As a core component in power electronic systems responsible for switching functions, the operating status of MOSFETs directly affects the safety and reliability of the entire system. In applications such as power conversion, motor drives, and new energy equipment, factors such as load short circuits, abnormal drives, or electromagnetic interference can all trigger overcurrent faults. If protective measures are inadequate, not only will the MOSFET itself be damaged, but it may also affect downstream circuits, causing system failure.

[0003] Current overcurrent protection schemes for MOSFETs have shortcomings in several aspects. At the current sampling level, conventional resistor sampling methods struggle to avoid the influence of lead resistance and parasitic parameters, leading to distorted sampling signals and hindering accurate subsequent judgment. At the signal conditioning level, some circuit designs are relatively simplified, with limited filtering capabilities, making them susceptible to high-frequency noise interference, further weakening the reliability of overcurrent detection. At the protection logic level, existing schemes mostly rely on a single overcurrent threshold setting, applying the same protection action to overcurrent events of different degrees, lacking a graded processing mechanism. This can easily cause unnecessary system interruptions during minor overcurrents, while inadequate protection may result in insufficient response during severe overcurrents.

[0004] Furthermore, existing technologies do not adequately address the dynamic changes in the operating environment of MOSFETs. The actual current-carrying capacity of a MOSFET decreases as the junction temperature increases, and differences in load type also affect its safe operating boundary. A fixed overcurrent threshold is difficult to adapt to these changes, easily leading to protection failure or false triggering under high-temperature or heavy-load conditions. Simultaneously, the response speed of some protection circuits is insufficient, making it difficult to complete shutdown before the overcurrent peak expands; the self-recovery strategy design is not perfect, frequent automatic resets may amplify the fault's impact, while purely manual resets reduce ease of use; the lack of fault data logging functionality also complicates subsequent fault analysis and system optimization.

[0005] As electronic devices develop towards higher power density, higher integration, and wider operating range, the aforementioned shortcomings become increasingly apparent, creating an urgent need for a MOSFET overcurrent protection technology that improves detection accuracy, response speed, environmental adaptability, and ease of maintenance. Summary of the Invention

[0006] The purpose of this invention is to provide a MOSFET safety protection system and control method based on overcurrent feedback, which helps to improve overcurrent detection accuracy, response speed and environmental adaptability, and can provide more comprehensive safety protection for MOSFETs.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A MOSFET safety protection system based on overcurrent feedback includes:

[0009] The system includes a current sampling module, a signal conditioning module, a feedback control module, a drive cutoff module, a self-recovery module, and a fault diagnosis module. The current sampling module is connected to the signal conditioning module, the signal conditioning module is connected to the feedback control module, the feedback control module is connected to the drive cutoff module, the drive cutoff module is connected to the self-recovery module, and the self-recovery module is connected to the fault diagnosis module.

[0010] The current sampling module is connected in series with a manganin resistor and uses a four-terminal wiring method to collect the current signal of the MOS transistor source circuit.

[0011] The signal conditioning module includes a differential amplifier circuit and a second-order low-pass filter circuit, used to convert the current signal into a voltage signal and remove high-frequency noise;

[0012] The feedback control module is used to convert the voltage signal after signal conditioning into a digital quantity and compare it with a preset multi-level overcurrent threshold to determine the overcurrent level.

[0013] The drive cutoff module is used to pull the gate voltage of the MOSFET below the threshold during overcurrent, thereby achieving rapid turn-off of the MOSFET.

[0014] The self-recovery module is used to set a delay according to the overcurrent level and achieve automatic reset through an electronic switch;

[0015] The fault diagnosis module is used to collect the peak current, duration and temperature data when an overcurrent occurs, and upload them to the main control unit through the communication interface.

[0016] Furthermore, a TVS diode is connected in parallel across the manganese copper resistor in the current sampling module.

[0017] Furthermore, the feedback control module is an MCU, and the MCU integrates a hardware comparator and a DMA controller.

[0018] Furthermore, the drive cutoff module employs a dual-channel high-speed optocoupler.

[0019] Furthermore, the self-recovery module also has a built-in counting unit for recording the number of consecutive overcurrents, locking the protection state after exceeding a preset upper limit, and supporting manual reset.

[0020] Furthermore, the fault diagnosis module acquires the temperature of the MOSFET through a surface-mount K-type thermocouple.

[0021] Furthermore, the system also includes an overcurrent warning unit, which collects the rate of change of current. ,when When the current change exceeds the preset threshold and the duration is greater than or equal to the preset time threshold, the drive current is reduced by 20%-40% in advance, and a warning signal is output. If the subsequent current does not exceed the overcurrent threshold, the drive current is gradually restored.

[0022] Furthermore, the system also includes an overcurrent level classification and graded protection unit, which is used to classify overcurrent levels, and the specific classification formula is as follows:

[0023] ;

[0024] In the formula, This is the nth level overcurrent threshold, in A. This refers to the rated operating current of the MOSFET, expressed in amperes (A). β is the coefficient for level n, β is the load fluctuation compensation coefficient, and N is the total number of levels. η is the maximum withstand current of the MOSFET, and η is the safety factor.

[0025] Furthermore, the system also includes a temperature-load coupled dynamic threshold correction unit, which is used to correct the overcurrent threshold by combining the MOSFET junction temperature and the load type. The specific formula is as follows:

[0026] ;

[0027] In the formula, For temperature T and load factor Overcurrent threshold at that time α is the reference threshold at 25℃ and rated load, T is the current junction temperature of the MOSFET, T25 is the reference temperature, and γ is the load correction factor.

[0028] This invention also provides a control method for a MOSFET safety protection system based on overcurrent feedback, applied to the aforementioned MOSFET safety protection system based on overcurrent feedback, comprising:

[0029] The current signal of the source circuit of the MOSFET is acquired through a current sampling module;

[0030] The current signal is converted into a standard voltage signal through a signal conditioning module;

[0031] The feedback control module converts the standard voltage signal into a digital quantity and compares it with preset multi-level overcurrent thresholds to determine the overcurrent level.

[0032] Execute the corresponding overcurrent protection action based on the overcurrent level;

[0033] The overcurrent threshold is adjusted in real time based on the junction temperature of the MOSFET and the load type.

[0034] Once the overcurrent fault is resolved, a reset operation is performed via the self-recovery module.

[0035] In summary, the present invention has at least one of the following beneficial technical effects:

[0036] The current sampling module employs manganin resistors with a four-terminal wiring method, which helps to suppress the adverse effects of lead resistance and parasitic parameters on sampling accuracy. Combined with a signal conditioning circuit featuring high common-mode rejection ratio and low offset voltage, and a composite digital filtering strategy, it can effectively reduce measurement deviations introduced by noise interference and improve the accuracy and stability of current detection.

[0037] The feedback control module integrates a high-speed analog-to-digital converter and a hardware comparator. Combined with the high-speed optocoupler and pull-down resistor design in the drive cutoff module, it can quickly pull down the gate voltage when an overcurrent occurs. This helps to turn off the MOSFET before the overcurrent peak expands further, reducing the risk of the device being subjected to overcurrent surges.

[0038] The overcurrent level classification and graded protection unit performs differentiated protection actions according to the degree of overcurrent. For minor overcurrent, it reduces power; for moderate overcurrent, it briefly shuts down and then restores power; and for severe overcurrent, it quickly cuts off and locks the circuit. This provides targeted safety protection for the MOSFET and also reduces the impact of protection actions on the normal operation of the system to a certain extent.

[0039] The temperature-load coupled dynamic threshold correction unit can combine the real-time junction temperature of the MOSFET with the load characteristics to adjust the overcurrent threshold online, so that the protection criteria are more in line with the actual current carrying capacity of the device. This reduces the risk of protection failure or false triggering caused by improper threshold setting under wide temperature range and load variation conditions.

[0040] The overcurrent prediction and early warning unit monitors the rate of change of current and intervenes to adjust the drive output before the overcurrent actually occurs or reaches its peak. This helps to suppress the trend of abnormal current rise from the source and reduce the actual frequency of overcurrent events.

[0041] In terms of fault recovery and maintenance, the self-recovery module adopts a design combining graded delay and continuous overcurrent counting. This avoids the risks associated with repeated automatic resets under persistent fault conditions while retaining the convenience of automatic recovery after transient faults are cleared. The soft-start strategy during reset also helps suppress secondary impacts. The fault diagnosis module can record key information such as overcurrent level, peak current, duration, and MOSFET junction temperature, providing data support for subsequent fault tracing and system optimization. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0043] Figure 2 This is a comparison chart of MOSFET failure rates under different overcurrent factors according to the present invention;

[0044] Figure 3 This is a comparison chart of the dynamic correction of the overcurrent threshold under temperature changes according to the present invention;

[0045] Figure 4 This is a comparison chart of the protection response time under different overcurrents according to the present invention;

[0046] Figure 5 This is a comparison chart of the protection false judgment rate under different interference intensities according to the present invention;

[0047] Figure 6 This is the timing diagram for the overcurrent prediction, early warning, and drive cutoff of the present invention;

[0048] Figure 7 This is a schematic diagram of the current sampling module circuit.

[0049] Figure 8 This is a schematic diagram of a differential amplifier circuit;

[0050] Figure 9 This is a schematic diagram of a second-order low-pass filter circuit;

[0051] Figure 10 This is a schematic diagram of an MCU circuit.

[0052] Figure 11 This is a schematic diagram of the circuit for driving the cutoff module. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0054] like Figure 1 As shown, this invention provides a MOSFET safety protection system based on overcurrent feedback, including: a current sampling module, a signal conditioning module, a feedback control module, a drive cutoff module, a self-recovery module, and a fault diagnosis module. The current sampling module is connected to the signal conditioning module, the signal conditioning module is connected to the feedback control module, the feedback control module is connected to the drive cutoff module, the drive cutoff module is connected to the self-recovery module, and the self-recovery module is connected to the fault diagnosis module. The following is a detailed description of each module:

[0055] 1. Current sampling module:

[0056] like Figure 7 As shown, the current sampling module is connected in series with a manganin resistor and uses a Kelvin four-terminal wiring method to reduce parasitic inductance and resistance interference. A TVS diode is connected in parallel across the manganin resistor, with a clamping voltage of 5V-10V. The current sampling module is used to collect the current signal of the source circuit of the MOSFET, with a sampling bandwidth ≥1MHz, a temperature coefficient ≤50ppm / ℃, and a power ≥5W.

[0057] 2. Signal Conditioning Module:

[0058] like Figure 8 and Figure 9 As shown, the signal conditioning module includes a differential amplifier circuit (with a continuously adjustable amplification factor of 20-50 times, converting the current signal into a 0-3V voltage signal) and a second-order low-pass filter circuit, used to convert the current signal into a voltage signal and remove high-frequency noise. The operational amplifier of the signal conditioning module is a rail-to-rail input / output type, and the filter circuit adopts an RC active filter topology, including a voltage follower composed of operational amplifiers.

[0059] This invention provides an embodiment in which the operational amplifier is selected as a rail-to-rail input / output type with a bandwidth ≥10MHz and a slew rate ≥5V / μs. The filter circuit adopts an RC active filter topology and includes a voltage follower composed of operational amplifiers to ensure that the filtered signal is not distorted.

[0060] 3. Feedback Control Module:

[0061] like Figure 10 As shown, the feedback control module converts the voltage signal after signal conditioning into a digital quantity and compares it with a preset multi-level overcurrent threshold to determine the overcurrent level. The feedback control module is a 32-bit MCU with a built-in 12-bit to 16-bit A / D converter, and integrates a hardware comparator and DMA controller. The MCU software algorithm of the feedback control module adopts a composite filtering strategy combining sliding window filtering and median filtering to reduce the false judgment rate of instantaneous interference. The overcurrent judgment duration is 10μs-100μs, and the threshold parameter can be passed through I... 2 Online configuration via C or SPI bus with a configuration accuracy of ≤0.01A.

[0062] 4. Driver cutoff module:

[0063] like Figure 11As shown, the drive cutoff module is used to pull the gate voltage of the MOSFET below the threshold during overcurrent, thereby achieving rapid turn-off of the MOSFET. It adopts a dual-channel high-speed optocoupler. The primary side of the dual-channel high-speed optocoupler of the drive cutoff module is connected in series with a 1kΩ-10kΩ current-limiting resistor, and the secondary output terminal is connected in parallel with a freewheeling diode to absorb the induced electromotive force during turn-off. During overcurrent, it pulls the gate voltage of the MOSFET below the threshold (0V). A 1nF-10nF debouncing capacitor is connected in parallel between the gate and source of the MOSFET. The drive cutoff module is used to ensure rapid turn-off of the MOSFET, with a turn-off time ≤1μs.

[0064] 5. Self-recovery module:

[0065] The self-recovery module is used to set a delay (0.1s-10s) according to the overcurrent level and achieve automatic reset through an electronic switch. The self-recovery module has a built-in counting unit to record the number of consecutive overcurrents. After exceeding the upper limit, the protection state is locked. Manual reset is supported. The delay circuit of the self-recovery module adopts dual backup of MCU timer and RC charging and discharging circuit. During automatic reset, a soft start strategy is adopted, driving the duty cycle to gradually increase from 0% to the set value, with an increase time of 1ms-10ms, to avoid the inrush current triggering the overcurrent again.

[0066] 6. Fault Diagnosis Module:

[0067] The fault diagnosis module is used to collect the peak current, duration and temperature data when an overcurrent occurs, and upload them to the main control unit through the communication interface. The fault diagnosis module collects the junction temperature of the MOSFET through a surface-mount K-type thermocouple with a temperature range of -50℃ to 175℃. The data sampling interval is set to 10ms-100ms. The fault information includes the overcurrent level, peak current, duration and junction temperature, and supports the storage of fault records.

[0068] The system also includes an overcurrent warning unit, which collects the rate of change of current. ,when When the current change exceeds the preset threshold and the duration is ≥5μs, the drive current is reduced by 20%-40% in advance and a warning signal is output. If the subsequent current does not exceed the overcurrent threshold, the drive current is gradually restored to achieve predictive protection and reduce false triggering.

[0069] The system also includes an overcurrent level classification and graded protection unit, which is used to classify overcurrent levels. The specific classification formula is as follows:

[0070] ;

[0071] In the formula, This is the nth level overcurrent threshold, in A. This refers to the rated operating current of the MOSFET, expressed in amperes (A). β is the coefficient for level n, β is the load fluctuation compensation coefficient, and N is the total number of levels. η is the maximum withstand current of the MOSFET, and η is the safety factor.

[0072] The system also includes a temperature-load coupling dynamic threshold correction unit, which is used to correct the overcurrent threshold by combining the MOSFET junction temperature and the load type. The specific formula is as follows:

[0073] ;

[0074] In the formula, For temperature T and load factor Overcurrent threshold at that time α is the reference threshold at 25℃ and rated load, α is the temperature coefficient, T is the current junction temperature of the MOSFET, T25 is the reference temperature, and γ is the load correction factor.

[0075] This invention also provides a control method for a MOSFET safety protection system based on overcurrent feedback, applied to the aforementioned MOSFET safety protection system based on overcurrent feedback, comprising:

[0076] The current signal of the source circuit of the MOSFET is acquired through a current sampling module;

[0077] The current signal is converted into a standard voltage signal through a signal conditioning module;

[0078] The feedback control module converts the standard voltage signal into a digital quantity and compares it with preset multi-level overcurrent thresholds to determine the overcurrent level.

[0079] Execute the corresponding overcurrent protection action based on the overcurrent level;

[0080] The overcurrent threshold is adjusted in real time based on the junction temperature of the MOSFET and the load type.

[0081] Once the overcurrent fault is resolved, a reset operation is performed via the self-recovery module.

[0082] Based on the overcurrent level, the corresponding overcurrent protection action is executed, specifically:

[0083] Level 1 overcurrent, <I≤ Reduce drive duty cycle by 10%-30%;

[0084] Level 2 overcurrent, <I≤ The driver will resume operation 50ms-500ms after being shut down.

[0085] Level 3 and above, I> It directly cuts off the driver, achieving hierarchical and precise protection.

[0086] Based on the MOSFET junction temperature and load type, the overcurrent threshold is adjusted as follows:

[0087] The junction temperature of the MOSFET is obtained, the load coefficient is obtained through the load detection circuit, and the real-time overcurrent threshold is calculated by substituting it into the threshold correction formula. The threshold is dynamically matched with the actual current carrying capacity of the MOSFET to avoid protection failure or false protection caused by high temperature or load fluctuation.

[0088] The present invention provides several specific embodiments to illustrate the above system and method in detail below:

[0089] Example 1: Safety Protection Circuit and Control Method for MOSFETs Used in Industrial Motor Drives. This example is applicable to a 20kW three-phase asynchronous motor drive system, protecting an IRF540N MOSFET with a rated operating current of [missing information]. =30A, maximum withstand current I max =60A, compatible with 12V-48V input voltage. The circuit adopts a multi-layer FR-4 PCB board design, with a sampling loop wiring length of 3cm and a line width of 3mm. Key components are mounted with heat sinks. The current sampling module uses a four-terminal connection with a 0.05Ω±0.5% manganese copper resistor, a temperature coefficient of 30ppm / ℃, a power of 10W, and a 6V / 10ATVS transistor connected in parallel at both ends. The sampling bandwidth is 1.5MHz, and it can collect currents from 0-50A with an error ≤0.5%.

[0090] The signal conditioning module uses an OPA2277 operational amplifier with an offset voltage of 0.1mV, a common-mode rejection ratio of 140dB, and a differential gain of 30x. Adjusted by a 10kΩ potentiometer, it converts a 0-2.5V current signal into a 0-3V voltage signal. The second-order RC active filter circuit uses resistors of 10kΩ ±0.1%, capacitors of 10nF ±5%, and a cutoff frequency of 50kHz. A voltage follower ensures distortion-free signal transmission.

[0091] The feedback control module uses an STM32F103ZET6 MCU with a built-in 12-bit A / D converter, a sampling rate of 200kSPS, and a hardware interrupt response time of 80ns. The software employs a 16-point sliding window filter plus a median filter, with an overcurrent detection duration of 50μs. The threshold is configured via the I²C bus with an accuracy of 0.01A.

[0092] The drive cutoff module uses a 6N137 optocoupler with a propagation delay of 80ns and an isolation withstand voltage of 3000Vrms. A 5kΩ resistor is connected in series on the primary side, and a 1N4148 diode is connected in parallel on the secondary side, along with a 51kΩ pull-down resistor in series. During overcurrent, the gate voltage is pulled down to -2V, and the turn-off time is ≤800ns. A 10nF capacitor is connected in parallel between the gate and the source to suppress oscillation.

[0093] The self-recovery module uses an MCU timer and RC charging / discharging circuit, with an adjustable delay of 0.5s-5s. The maximum continuous overcurrent count is 5 times; exceeding this limit requires manual reset. Automatic reset involves a 5ms soft start. The fault diagnosis module uses a K-type thermocouple to collect the junction temperature of the MOSFET, with a sampling interval of 50ms, storing 50 fault records and uploading them via RS485. In the overcurrent level classification unit, the total number of levels N=3, the load fluctuation compensation coefficient β=0.1, the safety factor η=0.8, k1=0.1, k2=0.3, and the coefficient for each level k3=0.5. The formula is... ,in: The overcurrent threshold for the nth level. The rated operating current is n, where n is the class number. This is the maximum withstand current. The calculation yields: =36.3A、 =42.9A、 =49.5A.

[0094] Protection measures: Level 1 reduces duty cycle by 20%; Level 2 shuts down and recovers after 200ms; Level 3 cuts off drive and locks. In the temperature and load coupling correction unit, a 25℃ reference threshold is used. =30A, temperature coefficient α=0.003 / ℃, load correction factor γ=0.05. The formula is... ,in: For temperature T and load factor The threshold value at which T is the current junction temperature and the reference temperature. =25℃. When T=80℃, When =1.5, =26.9A. The overcurrent prediction unit is set with a di / dt threshold of 5A / μs, where di / dt is the rate of change of current. If the current exceeds the threshold and lasts for ≥5μs, the drive current is reduced by 30% and an alarm is triggered. If the current does not exceed the threshold, it recovers within 10ms.

[0095] Table 1 Performance Comparison

[0096]

[0097] Table 1 shows that the sampling error reduction of the present invention is due to high-precision resistors and wiring optimization; the response speed improvement is due to high-speed optocouplers and hardware interrupts; the false judgment rate reduction is due to composite filtering and judgment delay; high-temperature reliability is achieved through dynamic threshold correction; the fault recording function facilitates traceability, and the overall performance is comprehensively superior to traditional solutions.

[0098] Example 2: Safety Protection Circuit and Control Method for MOSFETs in New Energy Storage Equipment

[0099] This embodiment is applied to a 10kWh energy storage battery management system to protect the IXFH60N100Q MOS transistor. =60A, I max =120A, adaptable to 24V-60V voltage, using military-grade components, PCB creepage distance ≥8mm. The current sampling module uses 0.03Ω±0.5% manganese copper resistors, four-terminal wiring, temperature coefficient 20ppm / ℃, power 15W, parallel 8V / 15ATVS transistor, sampling bandwidth 2MHz, sampling 0-100A current. The signal conditioning module uses AD8421 operational amplifier, offset voltage 0.05mV, amplification factor of 40x, converting 0-3V current signal to 0-3V voltage signal. In the second-order RC filter, the resistor is 5kΩ±0.1%, the capacitor is 20nF±5%, and the cutoff frequency is 80kHz.

[0100] The feedback control module uses an STM32H743VIT6 MCU with a built-in 16-bit A / D converter and a hardware interrupt response of ≤50ns. The software uses a 32-point sliding window filter plus median filtering, with a judgment duration of 30μs and a threshold configured via SPI. The drive cutoff module uses an AQV258 optocoupler, with a 3kΩ resistor in series on the primary side, a 1N4007 diode in parallel on the secondary side, and a 100kΩ pull-down resistor in series. During overcurrent, the gate is pulled to -3V, and the turn-off time is ≤500ns; a 5nF capacitor is connected in parallel between the gate and source. The self-recovery module has an adjustable delay of 0.1s-10s, a maximum of 8 consecutive overcurrent counts, supports manual / remote reset, and a soft-start time of 8ms. The fault diagnosis module uses an E-type thermocouple for temperature measurement, with a sampling interval of 30ms, stores 100 records, and uploads them via the CAN bus. In the current level classification unit, N=4, β=0.15, η=0.85, k1=0.1, k2=0.3, k3=0.5, k4=0.7. Substitute into the formula... ,have to =72.9A、 =83.7A、 =96A、 =108.3A.

[0101] Protection measures: Level 1 reduces duty cycle by 15%, Level 2 shuts off after 300ms, Level 3 shuts off after 1s, and Level 4 shuts off and locks off. In the temperature-load coupling correction unit... 25=60A, α=0.004 / ℃, γ=0.08. Substitute into formula When T=100℃, When =1.8, =48.05A. The overcurrent prediction unit is set with a di / dt threshold of 8A / μs. If the current exceeds the threshold and lasts for ≥5μs, the drive current is reduced by 40% and an alarm is triggered. If the current does not exceed the threshold, the current recovers within 5ms.

[0102] Table 2 Performance Comparison

[0103]

[0104] Table 2 shows that the high CMRR of this invention improves anti-interference capability; wide temperature range adaptation is achieved through precise temperature measurement and correction; continuous overcurrent counting avoids fault expansion; soft start eliminates reset impact; high-precision fault data provides support for energy storage system optimization and meets high reliability requirements.

[0105] like Figure 2 As shown, traditional single-threshold protection performs direct shutdown regardless of the severity of the overcurrent. For minor overcurrents, the shutdown impact leads to an 8% damage rate, while for severe overcurrents, delayed shutdown results in a damage rate as high as 98%. This invention implements differentiated measures based on the overcurrent level: for minor overcurrents, only the drive duty cycle is reduced to avoid unnecessary shutdown impact; for moderate overcurrents, a soft-start recovery is performed after a brief shutdown, balancing safety and availability; for severe and above overcurrents, the drive is quickly cut off and locked to prevent the fault from escalating. Combined with an overcurrent prediction and early warning unit, current surges are suppressed in advance. Even with a 3.0 times limit overcurrent, the damage rate is only 18.3%, far lower than traditional solutions. This tiered strategy solves the problem of "false shutdown for minor overcurrents" in traditional methods and avoids the risk of "delayed shutdown for severe overcurrents," significantly improving the operational safety of MOSFETs.

[0106] like Figure 3 As shown, traditional protection circuits use a fixed overcurrent threshold, maintaining 30A regardless of temperature changes. At low temperatures, the MOSFET's current-carrying capacity increases to 35.2A, and the fixed threshold leads to protection redundancy (matching degree only 85.2%), wasting the device's potential. At high temperatures, the current-carrying capacity drops to 18.5A, but the fixed threshold remains at 30A, far exceeding the device's tolerance and easily causing protection failure (matching degree only 61.7%). This invention uses temperature coefficient correction, where the threshold decreases synchronously with temperature increase: at -20℃, the threshold is 34.8A with a matching degree of 98.9%; at the extreme high temperature of 125℃, the threshold is 18.7A with a matching degree of 101.1%, always precisely matching the actual current-carrying capacity of the MOSFET. This dynamic adaptation capability solves the pain point of "false protection at low temperatures and protection failure at high temperatures" in traditional fixed threshold circuits under wide temperature range conditions, ensuring protection accuracy and MOSFET safety under different temperature environments.

[0107] like Figure 4As shown, traditional protection circuits rely on ordinary optocouplers and software judgment, with response times exceeding 1.6μs. These response times do not significantly decrease with increasing overcurrent, failing to quickly suppress overcurrent peaks and causing the MOSFET to withstand continuous overcurrent surges. This invention achieves nanosecond-level response through a dual-channel high-speed optocoupler (80ns propagation delay), a hardware comparator, and a DMA controller: a response time of 800ns at a 30A rated current and reduced to 350ns at a 90A extreme overcurrent, a 4.6-fold speed improvement, far below the 1μs safety response threshold. The larger the overcurrent, the more significant the improvement in response speed, because this invention prioritizes the handling of severe overcurrent signals via hardware interrupts, eliminating the need for complex software calculations. It can quickly cut off the MOSFET gate drive (pulling the gate voltage below 0V) before the overcurrent peak expands, effectively preventing the MOSFET from breaking down due to overcurrent surges. This rapid response characteristic solves the core pain point of traditional circuits—"response lag leading to protection failure"—and is particularly suitable for high-power, high-current applications.

[0108] like Figure 5 As shown, traditional protection circuits have rudimentary filtering designs, employing only simple RC filters. Their electromagnetic interference (EMI) resistance is weak, with a false alarm rate of 5.5% when interference intensity reaches level 3 (motor drive environment), and a staggering 12.1% when encountering level 5 extreme interference. This frequently results in "false shutdown without overcurrent" or "overcurrent leakage," severely impacting system stability. This invention employs a triple EMI suppression design: a four-terminal wiring of the current sampling module eliminates lead resistance interference; a second-order RC active filter + voltage follower in the signal conditioning module filters out high-frequency noise; and a combined strategy of sliding window filtering + median filtering in the feedback control module suppresses transient interference. Even with level 5 extreme EMI, the false alarm rate is only 0.8%, consistently below the acceptable threshold of 1%. This strong EMI suppression capability stems from the optimization of the entire sampling, conditioning, and judgment chain, solving the pain points of "high false alarm rate and poor reliability" in traditional circuits in complex industrial environments. It ensures accurate and stable MOSFET protection, making it suitable for high-interference scenarios such as motor drives and new energy equipment.

[0109] Figure 6This diagram demonstrates the timing logic of overcurrent prediction and warning, as well as drive cutoff. It visualizes the technical effects of the overcurrent prediction and warning unit and the drive cutoff module. When the current change rate di / dt = 6A / μs exceeds the preset threshold and persists for 5μs, the system initiates warning intervention without waiting for the overcurrent to occur, reducing the drive current by 30%, effectively suppressing further current increases and preventing entry into the overcurrent protection phase. If the current does not exceed the threshold after intervention, normal drive is gradually restored within 10ms, reducing the impact on system operation. If several pre-invalid overcurrents occur, the drive cutoff module quickly shuts off the gate drive within 400ns, preventing the overcurrent peak from expanding. The 400ns cutoff response time and the early intervention in the timing diagram fully demonstrate the speed and foresight of the protection circuit, overcoming the shortcomings of traditional passive response protection. This diagram provides a clear basis for software timing design and hardware performance verification, ensuring the coordinated operation of prediction and warning and rapid cutoff.

[0110] Embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0111] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0112] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0113] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0114] Contents not described in detail in this specification are prior art known to those skilled in the art. It is hereby indicated that the above description is intended to help those skilled in the art understand this invention, but does not limit the scope of protection of this invention. Any equivalent substitutions, modifications, improvements, or simplifications of the above descriptions that do not depart from the essential content of this invention fall within the scope of protection of this invention.

Claims

1. A MOSFET safety protection system based on overcurrent feedback, characterized in that, include: The system includes a current sampling module, a signal conditioning module, a feedback control module, a drive cutoff module, a self-recovery module, and a fault diagnosis module. The current sampling module is connected to the signal conditioning module, the signal conditioning module is connected to the feedback control module, the feedback control module is connected to the drive cutoff module, the drive cutoff module is connected to the self-recovery module, and the self-recovery module is connected to the fault diagnosis module. The current sampling module is connected in series with a manganin resistor and uses a four-terminal wiring method to collect the current signal of the MOS transistor source circuit. The signal conditioning module includes a differential amplifier circuit and a second-order low-pass filter circuit, used to convert the current signal into a voltage signal and remove high-frequency noise; The feedback control module is used to convert the voltage signal after signal conditioning into a digital quantity and compare it with a preset multi-level overcurrent threshold to determine the overcurrent level. The drive cutoff module is used to pull the gate voltage of the MOSFET below the threshold during overcurrent, thereby achieving rapid turn-off of the MOSFET. The self-recovery module is used to set a delay according to the overcurrent level and achieve automatic reset through an electronic switch; The fault diagnosis module is used to collect the peak current, duration and temperature data when an overcurrent occurs, and upload them to the main control unit through the communication interface.

2. The MOSFET safety protection system based on overcurrent feedback according to claim 1, characterized in that, A TVS diode is connected in parallel across the manganese copper resistor of the current sampling module.

3. The MOSFET safety protection system based on overcurrent feedback according to claim 1, characterized in that, The feedback control module is an MCU, and the MCU integrates a hardware comparator and a DMA controller.

4. The MOSFET safety protection system based on overcurrent feedback according to claim 1, characterized in that, The drive cutoff module uses a dual-channel high-speed optocoupler.

5. A MOSFET safety protection system based on overcurrent feedback according to claim 1, characterized in that, The self-recovery module also has a built-in counting unit to record the number of consecutive overcurrents, and locks the protection state after exceeding a preset upper limit, and supports manual reset.

6. The MOSFET safety protection system based on overcurrent feedback according to claim 1, characterized in that, The fault diagnosis module collects the temperature of the MOSFET through a surface-mount K-type thermocouple.

7. A MOSFET safety protection system based on overcurrent feedback according to claim 1, characterized in that, The system also includes an overcurrent warning unit, which collects the rate of change of current. ,when When the current change exceeds the preset threshold and the duration is greater than or equal to the preset time threshold, the drive current is reduced by 20%-40% in advance, and a warning signal is output. If the subsequent current does not exceed the overcurrent threshold, the drive current is gradually restored.

8. A MOSFET safety protection system based on overcurrent feedback according to claim 1, characterized in that, The system also includes an overcurrent level classification and graded protection unit, which is used to classify overcurrent levels. The specific classification formula is as follows: ； In the formula, This is the overcurrent threshold for the nth stage, expressed in A. This refers to the rated operating current of the MOSFET, expressed in amperes (A). β is the coefficient for level n, β is the load fluctuation compensation coefficient, and N is the total number of levels. η is the maximum withstand current of the MOSFET, and η is the safety factor.

9. A MOSFET safety protection system based on overcurrent feedback according to claim 1, characterized in that, The system also includes a temperature-load coupling dynamic threshold correction unit, which is used to correct the overcurrent threshold by combining the MOSFET junction temperature and the load type. The specific formula is as follows: ； In the formula, For temperature T and load factor Overcurrent threshold at that time α is the reference threshold at 25℃ and rated load, T is the current junction temperature of the MOSFET, T25 is the reference temperature, and γ is the load correction factor.

10. A control method for a MOSFET safety protection system based on overcurrent feedback, applied to the MOSFET safety protection system based on overcurrent feedback as described in any one of claims 1-9, characterized in that, include: The current signal of the source circuit of the MOSFET is acquired through a current sampling module; The current signal is converted into a standard voltage signal through a signal conditioning module; The feedback control module converts the standard voltage signal into a digital quantity and compares it with preset multi-level overcurrent thresholds to determine the overcurrent level. Execute the corresponding overcurrent protection action based on the overcurrent level; The overcurrent threshold is adjusted in real time based on the junction temperature of the MOSFET and the load type. Once the overcurrent fault is resolved, a reset operation is performed via the self-recovery module.

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