Brake energy recovery resistor device and control method under high soc of new energy vehicle

Abstract

This invention relates to the field of vehicle control for new energy vehicles, specifically to a braking energy recovery resistor device and control method for new energy vehicles under high SOC conditions. The device includes a vehicle control unit (VCU), a battery management system (BMS), a multi-function device, a high-voltage wiring harness, a drive motor, a braking resistor control unit, a braking resistor module, a temperature sensor, a cooling module, and a high-voltage contactor. The BMS and the multi-function device are communicatively connected to the VCU. The braking resistor control unit is also communicatively connected to the VCU. The multi-function device is connected to the power battery, drive motor, braking resistor module, and high-voltage wiring harness. The control terminals of the multi-function device and the braking resistor control unit are connected, enabling real-time information exchange and intelligent control. This invention aims to achieve uninterrupted electric braking under high SOC conditions, stable bus voltage, battery overcharge protection, long-term reliable resistor operation, and improved braking smoothness and safety.

Description

Technical Field

[0001] This invention relates to the field of vehicle control for new energy vehicles, specifically to a braking energy recovery resistor device and control method for new energy vehicles under high SOC. Background Technology

[0002] During braking, new energy commercial vehicles typically employ a combination of electric motor braking (regenerative braking) and mechanical braking to convert the vehicle's kinetic energy into electrical energy to recharge the power battery, thereby improving energy utilization efficiency. However, under conditions where the power battery has a high charge level, existing technologies exhibit the following significant drawbacks:

[0003] 1. When the battery pack is close to saturation (e.g., SOC > 85%), the battery internal resistance increases and the acceptable charging current decreases sharply, causing the battery to be unable to effectively absorb feedback energy. At this time, the motor's reverse torque is insufficient, the electric braking efficiency drops significantly, and the vehicle has to rely excessively on mechanical braking, which causes the brake pads to wear more quickly and even the risk of brake failure.

[0004] 2. Existing braking energy recovery schemes are mostly designed for the low to medium SOC range (such as 20%-80%), lacking dynamic energy dissipation mechanisms for high SOC conditions. Some schemes directly cut off energy feedback, resulting in sudden changes in braking torque, which affects driving smoothness and safety.

[0005] 3. Although some solutions mention using braking resistors to dissipate energy, their heat dissipation efficiency is limited. During long-term high-power operation (such as continuous downhill operation), the resistor device is prone to overheating, affecting the device's lifespan and safety, and may even cause fire hazards.

[0006] 4. Lack of systematic protection mechanism: The existing solution lacks graded and coordinated protection strategies under multiple abnormal operating conditions such as high SOC, bus overvoltage, and resistor overtemperature, resulting in low system reliability.

[0007] In summary, this invention proposes a braking energy recovery resistor device and control method for new energy vehicles under high SOC conditions to solve the problems mentioned in the background art. Summary of the Invention

[0008] A braking energy recovery resistor device for new energy vehicles under high SOC includes a vehicle controller (VCU), a battery management system (BMS), an all-in-one device, a high-voltage wiring harness, a braking resistor control unit, a braking resistor module, a temperature sensor, a cooling module, and a high-voltage contactor. The all-in-one device includes a motor controller (MCU). The battery management system (BMS) is communicatively connected to the vehicle controller (VCU) for real-time interaction of SOC information of the power battery.

[0009] The multi-function device (3) is connected to the high-voltage wiring harness of the drive motor. The braking resistor module (5) is connected in parallel to the drive motor through the multi-function device (3). The temperature sensor is installed on the braking resistor module to collect the resistor temperature and feed it back to the vehicle controller (VCU) through the braking resistor control unit. The vehicle controller (VCU) is connected to the control terminals of the battery management system (BMS), the multi-function device, and the braking resistor control unit, respectively. It is used to control the conduction, shutdown, and PWM duty cycle of the braking resistor control unit according to the received SOC information, bus voltage, brake pedal signal, and resistor temperature signal, so as to dissipate braking energy, stabilize bus voltage, and adjust braking torque through the braking resistor module under high SOC conditions.

[0010] Further specifying, the braking resistor control unit includes an IGBT power module, a freewheeling diode connected in antiparallel to the IGBT power module, a driving circuit, and a voltage sampling circuit. The input terminal of the voltage sampling circuit is connected to the DC bus, and its output terminal is connected to the driving circuit. The output terminal of the driving circuit is connected to the gate of the IGBT power module, and the main circuit of the IGBT power module is connected in series with the braking resistor module.

[0011] Furthermore, the cooling module is a forced air-cooled structure, and its control input terminal is connected to the vehicle controller (VCU). The vehicle controller (VCU) adjusts the operating intensity of the cooling module based on the resistance-temperature closed-loop feedback from the temperature sensor.

[0012] Furthermore, the vehicle controller (VCU) has a built-in high SOC hierarchical control strategy module, which is configured as follows:

[0013] When SOC≥95%, the braking resistor control unit is turned on at full power so that all braking energy is consumed by the braking resistor module.

[0014] When 85%≤SOC<95%, the braking resistor control unit is controlled to conduct with the corresponding duty cycle, so that the unreasonable part of the regenerated electrical energy is consumed by the braking resistor module, and the remaining part can enter the power battery.

[0015] When SOC < 85%, the braking resistor control unit is turned off, switching to the normal regenerative braking mode.

[0016] Furthermore, the vehicle control unit (VCU) also incorporates a multi-level system protection module, including resistor over-temperature power reduction protection, resistor over-temperature lockout protection, bus overvoltage forced conduction protection, overcurrent limiting protection, and fault self-locking and alarm protection. The resistor over-temperature power reduction protection reduces the duty cycle of the braking resistor control unit when the resistor temperature exceeds a first threshold. The resistor over-temperature lockout protection forcibly shuts down and locks the braking resistor control unit when the resistor temperature exceeds a second threshold. The bus overvoltage forced conduction protection forcibly conducts the braking resistor control unit when the bus voltage exceeds a voltage protection threshold. The overcurrent limiting protection limits the maximum duty cycle of the braking resistor control unit when the current flowing through the braking resistor module exceeds a current threshold. The fault self-locking and alarm protection enters a fault latching state and outputs an alarm signal when a system fault is detected.

[0017] A control method for a regenerative braking resistor device under high SOC in a new energy vehicle, the specific steps are as follows: Step S1, the BMS collects the SOC of the power battery in real time and uploads it to the VCU;

[0018] Step S2: When the vehicle brakes or coasts, the drive motor enters the generator state, and the generated regenerative power is fed back to the DC bus.

[0019] Step S3: The MCU detects the bus voltage in real time and sends it to the VCU. The VCU determines whether the current SOC has entered the preset high SOC range.

[0020] Step S4: When the high SOC condition is met and the bus voltage exceeds the preset protection threshold, the VCU drives the braking resistor control unit to turn on, so that the regenerated electrical energy is converted into heat energy consumption through the braking resistor module.

[0021] Step S5: The temperature sensor feeds back the temperature of the braking resistor module to the VCU in real time. The VCU adjusts the operating intensity of the cooling module according to the temperature value to cool the braking resistor module.

[0022] Step S6: When braking ends or SOC falls back to the allowable range, VCU controls the braking resistor control unit to turn off, and the system resumes energy feedback;

[0023] Step S7: During the operation of the braking resistor, the VCU adjusts the PWM duty cycle of the braking resistor control unit to achieve smooth adjustment of the braking torque.

[0024] Further defined, the preset high SOC range in step S4 includes: first range: SOC≥95%, at which point the VCU controls the braking resistor to operate at full power, and the electrical energy is completely consumed;

[0025] Second range: 85% ≤ SOC < 95%, at this time, the portion of the energy recovered by the VCU that is not properly controlled is consumed by the braking resistor, and the remaining energy is recharged to the power battery. Third range: SOC < 85%: The braking resistor is deactivated, and the system switches to the conventional regenerative braking mode.

[0026] Further specifying that in step S5, the VCU adjusts the operating intensity of the cooling module according to the temperature value, and the VCU compares the real-time temperature with the preset temperature threshold, and uses a closed-loop control method to linearly or segmentally adjust the speed of the cooling fan or the flow rate of the cooling medium.

[0027] Furthermore, in step S7, the VCU achieves smooth adjustment of braking torque by adjusting the PWM duty cycle. The VCU dynamically adjusts the rising and falling slopes of the PWM duty cycle according to the rate of change of the brake pedal opening or the fluctuation range of the bus voltage to avoid sudden torque changes.

[0028] Further, it also includes a multi-level system protection control strategy. When the temperature of the braking resistor module exceeds the first over-temperature threshold, the VCU performs a power reduction operation, reducing the PWM duty cycle; when the temperature exceeds the second over-temperature threshold, the VCU performs over-temperature lockout, forcibly shutting down the braking resistor control unit and issuing an alarm; when the bus voltage exceeds the overvoltage protection threshold, the VCU forcibly turns on the braking resistor control unit, regardless of the current SOC state; when overcurrent, IGBT fault, or communication fault is detected, the VCU enters a fault self-locking state, disconnects the high-voltage contactor, and outputs an alarm signal.

[0029] The advantages of this invention compared to the prior art are as follows:

[0030] 1. By introducing a braking resistor under high SOC conditions, regenerative electrical energy is converted into heat energy consumption, avoiding the problem of insufficient braking force caused by the forced disconnection of electric braking due to the inability of the battery to charge. This significantly improves braking safety under conditions such as long downhill slopes and achieves uninterrupted electric braking under high SOC conditions.

[0031] 2. The braking resistor control unit responds to bus overvoltage in real time, quickly conducts to consume excess energy, prevents bus voltage spikes from damaging high-voltage components such as motor controllers and DC / DC converters, stabilizes bus voltage, and protects high-voltage electrical components.

[0032] 3. Implement a graded control strategy to improve energy efficiency: The VCU has a built-in three-level control strategy for SOC ≥ 95%, 85%-95%, and < 85%, which maximizes the energy recovery ratio and avoids energy waste while ensuring safety.

[0033] 4. By dynamically adjusting the PWM duty cycle (adjusting the slope according to the rate of change of pedal opening or the amplitude of bus voltage fluctuation), linear changes in electric braking torque are achieved, eliminating shock and jerking sensations and improving driving comfort.

[0034] 5. Set up multi-level protection such as resistance over-temperature power reduction / lock-off, bus over-voltage forced conduction, overcurrent limiting, and fault self-locking alarm to ensure system safety and reliability under extreme operating conditions.

[0035] 6. The VCU adjusts the operating intensity of the forced air-cooling module according to the resistance temperature closed loop to ensure that the braking resistor does not overheat under long-term high-power operation, thus extending the life of the device. Attached Figure Description

[0036] Figure 1 This is a system structure block diagram of the present invention;

[0037] Figure 2 This is a structural block diagram of the braking resistor control unit of the present invention;

[0038] Figure 3 This is a flowchart of the system control logic of the present invention.

[0039] The labels in the diagram correspond to: 1-VCU, 2-BMS, 3-All-in-one device, 4-Brake resistor control unit, 5-Brake resistor module, 6-Temperature sensor, 7-Cooling module, 8-IGBT power module, and 9-Freewheeling diode. Detailed Implementation

[0040] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0041] Example:

[0042] like Figures 1-3 As shown, a regenerative braking resistor device for new energy vehicles under high SOC includes a vehicle controller (VCU1), a battery management system (BMS2), a multi-function device (M2), a high-voltage wiring harness, a braking resistor control unit (4), a braking resistor module (5), a temperature sensor (6), a cooling module (7), and a high-voltage contactor. The M2 includes a motor controller (MCU). VCU1, as the core control unit, communicates with BMS2 via a CAN bus. BMS2 collects parameters such as voltage, current, and temperature of the power battery in real time, calculates the current SOC value, and periodically sends it to VCU1. The M2 is directly connected to the drive motor and the high-voltage wiring harness of the braking resistor module (5). It integrates a voltage sampling circuit to monitor the bus voltage value in real time. The M2 communicates with VCU1 to upload the bus voltage data. The braking resistor control unit (4) is connected in series with the braking resistor module (5) and then connected to the M2 via a high-voltage contactor. The braking resistor module (5) is composed of multiple high-power resistance wires (or resistance sheets) connected in series and parallel, and its rated power is matched according to the maximum regenerative braking power of the vehicle.

[0043] The braking resistor control unit includes an IGBT power module 8, a freewheeling diode 9 connected in antiparallel to the IGBT power module 8, a drive circuit, and a voltage sampling circuit. The IGBT power module 8 serves as the main switching device, with its collector and emitter connected in series in the braking resistor circuit. The freewheeling diode 9 is connected in antiparallel across the IGBT to provide a freewheeling path for the inductive leakage current in the braking resistor when the IGBT is turned off, preventing voltage spikes from damaging the IGBT. The drive circuit receives the PWM control signal from VCU1, amplifies it through isolation, and then drives the gate of the IGBT. The voltage sampling circuit draws power directly from the DC bus. When the bus voltage exceeds the preset protection threshold, it can quickly output a forced turn-on signal to the drive circuit through a hardware comparator to achieve hardware-level fast protection against bus overvoltage.

[0044] Temperature sensor 6 is mounted close to the heat sink of braking resistor module 5. Its analog signal is sent to VCU1 after analog-to-digital conversion. Cooling module 7 is a forced air cooling structure, including an axial fan and a fan shroud. VCU1 adjusts the fan speed via PWM based on the resistance temperature fed back by the braking resistor control unit. The higher the temperature, the faster the fan speed, forming a closed-loop control.

[0045] The VCU has a built-in high SOC hierarchical control strategy module. When the VCU receives a brake pedal signal (brake switch or pedal opening value) or detects a coasting condition (accelerator pedal opening is 0 and vehicle speed is greater than the set value), it executes the following logic:

[0046] When SOC ≥ 95%, VCU1 sends a command to the multi-function device 3 and the braking resistor control unit 4 to prohibit the recharge of electrical energy to the battery and to completely consume the braking resistor. VCU1 drives the IGBT in the braking resistor control unit 4 to be fully turned on with a 100% duty cycle. All regenerated electrical energy is converted into heat energy dissipation by the braking resistor. At this time, the electric braking torque is determined by the resistance value of the braking resistor (R = U² / P). VCU1 does not perform PWM regulation to reduce switching losses.

[0047] When 85%≤SOC<95%, VCU allows the MCU to perform partial energy recharge to the braking battery (e.g., limiting the feedback power to no more than 50% of the battery's maximum allowable charging power). VCU1 drives the braking resistor with a dynamic PWM duty cycle to consume excess energy.

[0048] When SOC < 85%, VCU1 shuts off the braking resistor control unit 4, and the system switches to the normal regenerative braking mode, where all regenerative energy is returned to the battery.

[0049] During operation, the system performs resistor over-temperature protection. The first over-temperature threshold is: VCU1 limits the maximum PWM duty cycle to no more than 60% to reduce the heating power of the braking resistor; the second over-temperature threshold is: VCU1 forcibly shuts down the braking resistor control unit and requests MCU3 to reduce the regenerative braking power or request mechanical braking compensation, while the instrument panel issues an alarm prompt; the third over-temperature threshold is: VCU1 disconnects the high-voltage contactor, completely prohibiting energy feedback and resistor operation, and enters a safe state.

[0050] Bus overvoltage protection: When the voltage sampling circuit detects that the bus voltage exceeds the hardware threshold, the IGBT is forcibly turned on through hardware logic, which is not controlled by the software of VCU1, to ensure that the bus voltage will not rise further.

[0051] Overcurrent protection: When the current flowing through the braking resistor exceeds the set value, VCU1 automatically reduces the PWM duty cycle to limit the current. If the current continues to exceed the limit, the IGBT will be turned off and an alarm will be triggered.

[0052] Fault latch-up: When a serious fault such as IGBT short circuit, drive circuit failure, or communication loss is detected, the VCU enters the fault latch-up state, cuts off the high-voltage contactor, and displays a fault code on the instrument. Manual power-on reset is required to release the fault.

[0053] A control method for a regenerative braking resistor device under high SOC in a new energy vehicle, the specific steps of which are as follows:

[0054] Step S1: The BMS collects the SOC of the power battery in real time and uploads it to the VCU;

[0055] Step S2: When the vehicle brakes or coasts, the drive motor enters the generator state, and the generated regenerative power is fed back to the DC bus.

[0056] Step S3: The MCU detects the bus voltage in real time and sends it to the VCU. The VCU determines whether the current SOC has entered the preset high SOC range.

[0057] Step S4: When the high SOC condition is met and the bus voltage exceeds the preset protection threshold, the VCU drives the braking resistor control unit to turn on, so that the regenerated electrical energy is converted into heat energy consumption through the braking resistor module. If SOC ≥ 95%, the VCU controls the full power to be applied to the braking resistor. If 85% ≤ SOC < 95%, the VCU controls the unreasonable part of the recovered electrical energy to be consumed by the braking resistor, and the remaining energy is returned to the power battery. If SOC < 85%, the braking resistor is deactivated and the system switches to the conventional regenerative braking mode.

[0058] Step S5: The braking resistor control unit feeds back the temperature of the braking resistor module to the VCU in real time. The VCU adjusts the operating intensity of the cooling module according to the temperature value. The VCU compares the real-time temperature with the preset temperature threshold and uses a closed-loop control method to linearly or segmentally adjust the speed of the cooling fan or the flow rate of the cooling medium.

[0059] Step S6: When braking ends or SOC falls back to the allowable range, VCU controls the braking resistor control unit to turn off, and the system restores electrical energy to fully recharge the power battery.

[0060] Step S7: During the operation of the braking resistor, the VCU adjusts the PWM duty cycle of the braking resistor control unit to achieve smooth adjustment of the braking torque. The VCU dynamically adjusts the rising and falling slopes of the PWM duty cycle according to the rate of change of the brake pedal opening or the fluctuation of the bus voltage to avoid sudden torque changes.

[0061] If the vehicle enters the high SOC range, the braking resistor will continue to operate, generating a large amount of heat. The VCU uses closed-loop control to keep the cooling fan running at full speed and monitors the resistor temperature in real time. If the resistor temperature approaches the first-level threshold, the VCU automatically reduces the PWM duty cycle (i.e., reduces the intensity of electric braking) and requests mechanical braking to compensate for a portion of the braking force, ensuring that the total braking force of the vehicle remains unchanged. Through this "thermal derating" strategy, both the braking resistor device and the braking safety on long downhill slopes can be protected.

[0062] If the resistor temperature continues to rise above the second over-temperature threshold, the VCU will directly and forcibly shut down the brake resistor control unit's lockout output, issuing an over-temperature alarm on the vehicle's instrument panel to remind the driver to pay attention to the vehicle's status. If the temperature further exceeds the third over-temperature threshold, the VCU will directly disconnect the high-voltage contactor in the brake resistor circuit, completely disengaging the brake energy consumption function and entering a safe shutdown state to prevent the brake resistor from overheating and burning out, thus avoiding safety risks. Throughout system operation, hardware-level bus overvoltage protection logic is retained. When the DC bus voltage exceeds the preset hardware protection threshold, without waiting for VCU software commands, the voltage sampling circuit will directly output a forced conduction signal through the hardware comparator, driving the IGBT to conduct and consume excess power, responding to overvoltage faults as quickly as possible and preventing high-voltage components from being damaged due to overvoltage. When serious faults such as overcurrent, IGBT failure, or communication loss are detected, the VCU directly enters a fault self-locking state, disconnecting the high-voltage contactor and outputting the corresponding fault code. Only after manual troubleshooting and power-on reset can the latching state be released, ensuring system safety after a fault.

[0063] The above provides a detailed description of the braking energy recovery resistor device and control method for new energy vehicles under high SOC. The specific embodiments are only used to help understand the method and core ideas of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A regenerative braking device for high state of charge (SOC) in new energy vehicles, characterized in that: The system includes a vehicle control unit (VCU) (1), a battery management system (BMS) (2), an all-in-one device (3), a high-voltage harness, a braking resistor control unit (4), a braking resistor module (5), a temperature sensor (6), a cooling module (7), and a high-voltage contactor. The all-in-one device includes a motor control unit (MCU). The battery management system (BMS) (2) is communicatively connected to the vehicle control unit (VCU) (1) for real-time interaction of information such as the SOC of the power battery. The all-in-one device (3) is connected to the drive motor via a high-voltage harness and is connected in parallel with the braking resistor module (5) to the drive motor via the all-in-one device (3). The temperature sensor (6) is located on the braking resistor module (5) and is used to collect the resistance temperature and feed it back to the vehicle control unit (VCU) (1) through the braking resistor control unit (4). The vehicle controller (VCU) (1) is connected to the control terminals of the battery management system (BMS) (2), the multi-function module (3), and the braking resistor control unit (4). Based on the received SOC information, bus voltage, brake pedal signal, and resistor temperature signal, the VCU controls the conduction, shutdown, and PWM duty cycle of the braking resistor control unit to dissipate braking energy, stabilize the bus voltage, and adjust the braking torque through the braking resistor module under high SOC conditions.

2. The regenerative braking device for high SOC in new energy vehicles according to claim 1, characterized in that: The braking resistor control unit (4) includes an IGBT power module (8), a freewheeling diode (9) connected in antiparallel to the IGBT power module (8), a driving circuit, and a voltage sampling circuit. The input terminal of the voltage sampling circuit is connected to the DC bus, and its output terminal is connected to the driving circuit. The output terminal of the driving circuit is connected to the gate of the IGBT power module. The main circuit of the IGBT power module is connected in series with the braking resistor module.

3. The regenerative braking device for high SOC in new energy vehicles according to claim 1, characterized in that: The cooling module (7) is a forced air-cooled structure. Its control input terminal is connected to the brake resistor control unit (4). The vehicle controller (VCU) (1) adjusts the operating intensity of the cooling module (7) according to the resistance-temperature closed loop feedback from the brake resistor control unit (4) and the temperature sensor (6).

4. The regenerative braking device for high SOC in new energy vehicles according to claim 1, characterized in that: The vehicle controller (VCU) (1) has a built-in high SOC hierarchical control strategy module, configured as follows: When SOC≥95%, the braking resistor control unit (4) is turned on at full power so that all braking energy is consumed by the braking resistor module; When 85%≤SOC<95%, the braking resistor control unit (4) is controlled to conduct with the corresponding duty cycle, so that the regenerated electrical energy is consumed by the braking resistor module, and the remaining part can enter the power battery. When SOC < 85%, the braking resistor control unit (4) is turned off, switching to the normal regenerative braking mode.

5. The regenerative braking device for high SOC in new energy vehicles according to claim 1, characterized in that... The vehicle controller VCU (1) also has a built-in multi-level system protection module, including resistor over-temperature power reduction protection function, resistor over-temperature lockout protection function, bus overvoltage forced conduction protection function, overcurrent current limiting protection function and fault self-locking and alarm protection function. The resistor over-temperature power reduction protection function reduces the conduction duty cycle of the braking resistor control unit when the resistor temperature exceeds the first threshold. The resistor over-temperature lockout protection function forcibly shuts down and locks the braking resistor control unit when the resistor temperature exceeds the second threshold. The bus overvoltage forced conduction protection function forcibly conducts the braking resistor control unit when the bus voltage exceeds the voltage protection threshold. The overcurrent current limiting protection function limits the maximum conduction duty cycle of the braking resistor control unit when the current flowing through the braking resistor module exceeds the current threshold. The fault self-locking and alarm protection function enters the fault latching state and outputs an alarm signal when a system fault is detected.

6. A control method for a regenerative braking resistor device under high SOC in a new energy vehicle according to any one of claims 1-5, characterized in that: The specific steps are as follows: Step S1: The BMS collects the SOC of the power battery in real time and uploads it to the VCU; Step S2: When the vehicle brakes or coasts, the drive motor enters the generator state, and the generated regenerative power is fed back to the DC bus. Step S3: The MCU detects the bus voltage in real time and sends it to the VCU. The VCU determines whether the current SOC has entered the preset high SOC range. Step S4: When the high SOC condition is met and the bus voltage exceeds the preset protection threshold, the VCU drives the braking resistor control unit to turn on, so that the regenerated electrical energy is converted into heat energy consumption through the braking resistor module. Step S5: The temperature sensor feeds back the temperature of the braking resistor module to the VCU in real time. The VCU adjusts the operating intensity of the cooling module according to the temperature value to cool the braking resistor module. Step S6: When braking ends or SOC falls back to the allowable range, VCU controls the braking resistor control unit to turn off, and the system resumes energy feedback; Step S7: During the operation of the braking resistor, the VCU adjusts the PWM duty cycle of the braking resistor control unit to achieve smooth adjustment of the braking torque.

7. The control method for a regenerative braking resistor device under high SOC in a new energy vehicle according to claim 6, characterized in that: The preset high SOC range in step S4 includes: First range: SOC≥95%, at this time the VCU controls the full power to engage the braking resistor, and the electrical energy is completely consumed; Second range: 85%≤SOC<95%, at this time, the unreasonable part of the energy recovered by the VCU is consumed by the braking resistor, and the remaining energy is recharged to the power battery.

8. The control method for a regenerative braking resistor device under high SOC in a new energy vehicle according to claim 6, characterized in that: In step S5, the VCU adjusts the operating intensity of the cooling module according to the temperature value. The VCU compares the real-time temperature with the preset temperature threshold and uses a closed-loop control method to linearly or segmentally adjust the speed of the cooling fan or the flow rate of the cooling medium.

9. The control method for a regenerative braking resistor device under high SOC in a new energy vehicle according to claim 6, characterized in that: In step S7, the VCU achieves smooth adjustment of braking torque by adjusting the PWM duty cycle. The VCU dynamically adjusts the rising and falling slopes of the PWM duty cycle according to the rate of change of the brake pedal opening or the fluctuation of the bus voltage to avoid sudden torque changes.

10. The control method for a regenerative braking resistor device under high SOC in a new energy vehicle according to claim 6, characterized in that: It also includes a multi-level system protection control strategy. When the temperature of the braking resistor module exceeds the first over-temperature threshold, the VCU performs a power reduction operation, reducing the PWM duty cycle. When the temperature exceeds the second over-temperature threshold, the VCU performs over-temperature lockout, forcibly shutting down the braking resistor control unit and issuing an alarm. When the bus voltage exceeds the overvoltage protection threshold, the VCU forcibly turns on the braking resistor control unit, regardless of the current SOC state. When an overcurrent, IGBT fault, or communication fault is detected, the VCU enters a fault self-locking state, disconnects the high-voltage contactor, and outputs an alarm signal.

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