A control method for inhibiting large current pulses of a hybrid vehicle battery in a low temperature environment

Abstract

The present application relates to the technical field of new energy vehicles, and specifically relates to a control method for inhibiting battery pulse large current of a hybrid vehicle in a low-temperature environment, comprising: building an energy management system with HCU as the core, and realizing information interaction of multiple components through CAN communication; after the vehicle is powered on, the HCU identifies the cold engine mode and the hot engine mode according to the battery charging and discharging power and the temperature; the shift sequence is planned according to the mode and the engine working demand (the cold engine mode is fixed at D gear, and the hot engine mode is dynamically shifted); the maximum allowable driving / braking torque of the EM2 motor is calculated in combination with the battery charging and discharging power, the EM1 motor power and the power consumption of the electrical accessories; the torque of the EM2 motor is controlled within the limit, and the battery power is limited within the allowable range. The present application can completely eliminate the battery instantaneous overcharging and overdischarging (the instantaneous over-limit power is more than 10 kW) during low-temperature gear shifting, protect the battery life and safety, take into account the power and driving smoothness, and is suitable for battery control of a hybrid vehicle in a low-temperature environment.

Description

Technical Field

[0001] This invention relates to the field of new energy vehicle technology, and in particular to a control method for suppressing large pulse currents in hybrid vehicle batteries under low-temperature conditions. Background Technology

[0002] Hybrid electric vehicles combine the advantages of traditional gasoline vehicles and pure electric vehicles. They can autonomously decide whether to operate in pure electric or hybrid mode based on working scenarios and power demands, thus improving problems such as high fuel consumption and emissions in urban driving, and eliminating range anxiety. They can achieve optimal energy distribution in different scenarios. A certain type of hybrid vehicle is equipped with a multi-speed power-split hybrid transmission that uses a single planetary gear set for power splitting and a 2x2 AMT (Automated Manual Transmission) for speed and torque adjustment, fully leveraging the fuel-saving capabilities and power advantages of this hybrid system.

[0003] However, in low-temperature environments (below -5°C), when a vehicle shifts gears, the shift torque compensation and motor speed regulation processes can cause the power battery to over-discharge (exceeding the battery's maximum allowable discharge power) and overcharge (exceeding the battery's maximum allowable charging power). The pulse current generated during gear shifting has a significant impact on battery performance and lifespan. Specifically, compared to gasoline vehicles, hybrid vehicles add a power battery as an energy storage unit. The performance of this power battery is significantly affected by temperature. In low-temperature environments, due to reduced lithium-ion activity, increased electrode fluid viscosity, and increased battery internal resistance, if the battery's power usage is not limited, it can lead to battery capacity degradation and risks such as internal short circuits.

[0004] Furthermore, a certain type of vehicle equipped with a 2x2 combined AMT power-split hybrid transmission exhibits two typical power over-limit scenarios when shifting gears in low-temperature environments: The first is the ICE-AMT shifting discharge power over-limit. During engine shifting, to avoid power interruption, the EM2 motor needs to increase the power output of the engine before shifting for torque compensation. Simultaneously, during engine shifting and speed adjustment, the EM1 motor participates in the planetary gear speed regulation process, which is in an electric power consumption process. The superposition of these two power demands causes the actual battery power to exceed the battery's maximum allowable discharge power. The second is the EM2-AMT shifting charging power over-limit. During EM2 motor shifting, the EM2 does not participate in vehicle drive. To ensure that the vehicle's power does not decrease, the engine's power output needs to be increased. However, after the engine power increases, due to the power splitting effect, the EM1 motor's power generation increases simultaneously. During the shifting synchronous speed regulation stage, the EM2 motor is in a braking power generation state, which generates a large pulse charging power. The superposition of these two charging power causes the actual battery power to exceed the battery's maximum allowable charging power. In both of the above scenarios, the battery experiences instantaneous overcharging and over-discharging, with instantaneous over-limit power exceeding 10kW, posing a serious risk to battery life and safety.

[0005] Therefore, due to factors such as the limited performance of the battery itself and the reduced limit of the usable charging and discharging power in low-temperature environments, there is an urgent need for a control method to suppress the pulsed high current of hybrid vehicle batteries in low-temperature environments in order to protect the battery power from being overused. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a control method for suppressing high-current pulses in hybrid vehicle batteries at low temperatures. This addresses the technical problem in existing technologies where battery performance is limited at low temperatures (below -5°C), and hybrid vehicles equipped with a 2x2 AMT power-split hybrid transmission experience overcharging and over-discharging (instantaneous over-limit power exceeding 10kW) during gear shifts due to shift torque compensation and motor speed regulation, thus affecting battery life and safety. By intelligently identifying the vehicle's hot / cold engine mode, planning the optimal shift sequence, and controlling the EM2 motor torque limit, the real-time power consumption of the battery is strictly controlled within the allowable charge / discharge power range, protecting the battery from over-limit use.

[0007] The above objectives are achieved through the following technical solutions: A control method for suppressing pulsed high current in hybrid vehicle batteries under low-temperature conditions is applied to hybrid vehicles equipped with multi-speed power-split hybrid transmissions. The multi-speed power-split hybrid transmission uses a single planetary gear set for power splitting and is configured with a 2x2 automatic manual transmission (AMT) for speed and torque adjustment. The control method includes the following steps: Step (1): Build an energy management system with the vehicle controller HCU as the control core. The energy management system includes a battery and battery management system (BMS), an engine and engine management system (EMS), a motor and motor controller (PEU), and electrical accessories. The vehicle controller HCU communicates with the battery management system (BMS), the engine management system (EMS), the motor controller (PEU), and the electrical accessories via CAN communication. Step (2): After the vehicle is powered on at low voltage and the CAN network is communicating normally, the vehicle controller HCU receives the maximum allowable discharge power, maximum allowable charging power and battery temperature information sent by the battery management system BMS, and identifies the cold or hot engine mode of the vehicle; if the maximum allowable discharge power and maximum allowable charging power of the battery are lower than the set threshold, or the battery temperature is lower than the set threshold, the vehicle enters the cold engine mode; if the maximum allowable discharge power and maximum allowable charging power of the battery are higher than the set threshold, or the battery temperature is higher than the set threshold, the vehicle enters the hot engine mode. Step (3): The vehicle controller HCU autonomously plans and decides on the corresponding shift sequence based on the identified hot and cold engine modes; Step (4): The vehicle controller HCU receives the maximum allowable discharge power and maximum allowable charging power of the battery, as well as the power consumption of the electrical accessories and the actual power of the EM1 motor, sent by the battery management system BMS, and calculates the maximum allowable driving torque and maximum allowable braking torque of the EM2 motor respectively. Step (5): The vehicle controller HCU controls the driving torque of the EM2 motor to not exceed the maximum allowable driving torque, and controls the braking torque of the EM2 motor to not exceed the maximum allowable braking torque, thereby limiting the real-time power consumption of the battery to within the allowable charging and discharging power range of the battery.

[0008] Preferably, the cold engine mode and the hot engine mode in step (2) can be switched between each other; in the cold engine mode, if the maximum allowable discharge power and the maximum allowable charging power of the battery are higher than the set threshold, or the battery temperature is higher than the set threshold, the vehicle switches from the cold engine mode to the hot engine mode; after the vehicle is powered off at low voltage, both the cold engine mode and the hot engine mode switch to the initialization state.

[0009] Preferably, the initialization state in step (2) is the initial state before the vehicle is powered on at low voltage; after the vehicle is powered on at low voltage, the vehicle controller HCU first enters the initialization state, and then determines whether to enter the cold engine mode or the hot engine mode based on the battery parameters.

[0010] Preferably, in step (3), when the vehicle is in cold engine mode, the shift sequence is divided into cold engine mode-pure electric gear sequence and cold engine mode-hybrid gear sequence according to whether there is an engine working requirement; the cold engine mode-pure electric gear sequence is N0-D4-N0-R4-N0; the cold engine mode-hybrid gear sequence is N0-N4-D4-N4-R4-N4-N0.

[0011] Preferably, in step (3), when the vehicle is in hot engine mode, the shift sequence is divided into hot engine mode-pure electric gear sequence and hot engine mode-hybrid gear sequence according to whether there is an engine working requirement; the hot engine mode-pure electric gear sequence is N0-D1-D3-D4-D3-D1-N0-R1-N0; the hot engine mode-hybrid gear sequence is N0-N1-D1-D3-D4-D3-D1-N1-R1-N1-N0.

[0012] Preferably, the specific process for calculating the maximum allowable driving torque of the EM2 motor in step (4) is as follows: First, based on the maximum allowable discharge power of the battery, the actual power of the EM1 motor, and the power consumed by the electrical accessories, the maximum usable discharge power of the EM2 motor is calculated. The calculation formula is: Maximum usable discharge power of the EM2 motor = maximum allowable discharge power of the battery - (actual power of the EM1 motor + power consumed by the electrical accessories); Second, combining the electric efficiency and angular velocity of the EM2 motor, the maximum usable discharge power of the EM2 motor is converted into the maximum allowable driving torque of the EM2 motor.

[0013] Preferably, the specific process for calculating the maximum allowable braking torque of the EM2 motor in step (4) is as follows: First, based on the maximum allowable charging power of the battery, the actual power of the EM1 motor, and the power consumed by the electrical accessories, the maximum available charging power of the EM2 motor is calculated. The calculation formula is: Maximum available charging power of the EM2 motor = maximum allowable charging power of the battery + (actual power of the EM1 motor + power consumed by the electrical accessories); Second, combined with the power generation efficiency and angular velocity of the EM2 motor, the maximum available charging power of the EM2 motor is converted into the maximum allowable braking torque of the EM2 motor.

[0014] Preferably, the electrical accessories include a DC-DC converter, an air conditioning compressor (EAC), and an electric air pump (APC); the vehicle controller (HCU) receives the operating voltage and current of the DC-DC converter, the air conditioning compressor (EAC), and the electric air pump (APC) to calculate the power consumption of the electrical accessories.

[0015] Preferably, the actual power of the EM1 motor reflects the power generation power of the engine; the vehicle controller HCU receives the operating speed and torque of the EM1 motor and the EM2 motor, as well as the operating speed and torque of the engine, and calculates the required power of the engine and the required power of the EM2 motor in combination with the driving power requirements of the vehicle, and converts the required power into required torque and required speed, and sends them to the engine management system EMS and the motor controller PEU through CAN communication.

[0016] Preferably, the low-temperature environment is an environment with a temperature below -5°C; in the low-temperature environment, if the control method is not executed, when the vehicle shifts gears, the battery will experience instantaneous overcharging or over-discharging, and the instantaneous over-limit power will reach more than 10kW.

[0017] This invention provides a control method for suppressing high-current pulses in hybrid vehicle batteries at low temperatures. This method effectively solves the problem of battery overcharging and over-discharging (instantaneous over-limit power exceeding 10kW) during gear shifting in hybrid vehicles at low temperatures (below -5°C). By identifying hot and cold engine modes, planning the shifting sequence, and controlling the torque of the EM2 motor, the battery power is limited to an allowable range, protecting the battery from degradation and short circuits, extending its lifespan, reducing safety risks, and also considering the overall vehicle power and driving smoothness. Specific beneficial effects are as follows: 1. Completely eliminate battery pulse high current: By fixing the D gear in cold mode (without performing gear shifting), the power superposition caused by "torque compensation + motor speed regulation" during gear shifting is avoided from the root, eliminating the triggering conditions for instantaneous overcharging and over-discharging of the battery; at the same time, through EM2 motor torque limit control in all modes, it is further ensured that the real-time power of the battery does not exceed the allowable range, completely solving the problem of instantaneous over-limit power of the battery exceeding 10kW during low-temperature gear shifting.

[0018] 2. Protecting battery life and safety: In response to the characteristics of reduced lithium-ion activity, increased electrode fluid viscosity, and increased internal resistance in low-temperature environments, the battery charging and discharging power is strictly controlled to effectively avoid risks such as battery capacity decay and internal short circuits. This significantly extends the service life of the power battery in low-temperature environments and reduces the vehicle safety hazards caused by battery failures.

[0019] 3. Balancing power needs and smoothness: In cold engine mode, the vehicle operates in a fixed gear, avoiding the problem of large torque fluctuations caused by low power limits, which leads to poor driving smoothness; in warm engine mode, dynamic shifting is restored, giving full play to the torque output capability and fuel-saving advantages of the 2x2 AMT multi-gear power split hybrid transmission; at the same time, the switching between cold and warm engine modes and gear adjustment are automatically executed based on real-time parameters, and the EM2 motor torque gradual control avoids power fluctuations and driving jerks, ensuring the smoothness of the entire vehicle's driving.

[0020] 4. Strong system coordination: With the vehicle controller HCU as the core, it realizes information interaction and coordinated control of BMS, EMS, PEU and electrical accessories through CAN communication. It has comprehensive data acquisition, rapid decision response and can dynamically adjust the control strategy according to battery status, ambient temperature and vehicle power demand, making it highly adaptable. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a multi-gear power split hybrid system in a certain type of vehicle, which is part of the control method for suppressing large pulse currents in hybrid vehicle batteries under low-temperature conditions as described in this invention. In the diagram, ICE-AMT (engine-AMT transmission), EM2-AMT (EM2 motor-AMT transmission), EMS (engine management system), PEU (motor controller), SAU (shift actuator controller), HCU (vehicle controller), CAN (controller area network), and Out (transmission output). Figure 2 This is a schematic diagram illustrating the excessive discharge power during engine gear shifting at low temperatures in the control method for suppressing large pulse currents in hybrid vehicle batteries under low-temperature environments, as described in this invention. The diagram shows torque reduction (engine torque reduction phase), disengagement speed adjustment (engine disengagement speed adjustment phase), gear engagement torque recovery (engine engagement torque recovery phase), target gear (engine target gear), actual gear (engine actual gear), throttle opening (driver's throttle input), and over-discharge power (battery power exceeding the maximum permissible discharge value). Figure 3 This is a schematic diagram illustrating the charging power exceeding the limit during the TM gear shifting process at low temperatures in the control method for suppressing pulsed high current in hybrid vehicle batteries under low-temperature environments, as described in this invention. The diagram shows: torque reduction (EM2 motor torque reduction stage), disengagement speed adjustment (EM2 motor disengagement speed adjustment stage), gear engagement torque recovery (EM2 motor gear engagement torque recovery stage), target gear (EM2 motor target gear), actual gear (EM2 motor actual gear), and overcharging power (the power value of the battery exceeding the maximum allowable charging value). Figure 4 The diagram shows the topology of the vehicle energy management system in the control method for suppressing large pulse currents in hybrid vehicle batteries under low-temperature conditions, as described in this invention. The components in the diagram are: BMS (Battery Management System), EMS (Engine Management System), HCU (Vehicle Controller), PEU (Motor Controller), DCDC (DC-CDC Converter), EAC (Air Conditioning Compressor), and APC (Electric Air Pump). Figure 5This is a schematic diagram illustrating the principle of cold / hot engine state recognition in the control method for suppressing large pulse currents in hybrid vehicle batteries under low-temperature environments, as described in this invention. In the diagram, Init (initialization state), Cold (cold engine mode), Warm (hot engine mode), value A (maximum allowable discharge power threshold of the battery), value B (maximum allowable charging power threshold of the battery), value C (battery temperature threshold, triggered by cold engine mode), value D (maximum allowable discharge power threshold of the battery, triggered by hot engine mode), value E (maximum allowable charging power threshold of the battery, triggered by hot engine mode), and value F (battery temperature threshold, triggered by hot engine mode). Figure 6 This is a schematic diagram of the gear sequence in the control method for suppressing large pulse current of hybrid vehicle battery in low temperature environment according to the present invention; in the figure, N0 (neutral initial position), N1 (hybrid mode neutral 1), N4 (hybrid mode neutral 4), D1 (forward gear 1), D3 (forward gear 3), D4 (forward gear 4), R1 (reverse gear 1), R4 (reverse gear 4). Figure 7 This is a schematic diagram illustrating the calculation principle of the maximum allowable driving torque of the EM2 motor in the control method for suppressing large pulse currents in hybrid vehicle batteries under low-temperature conditions as described in this invention. Figure 8 This is a schematic diagram illustrating the calculation principle of the maximum allowable braking torque of the EM2 motor in the control method for suppressing large pulse currents in hybrid vehicle batteries under low-temperature conditions, as described in this invention. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. The described embodiments are merely some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] like Figures 1-8 As shown, this solution provides a control method for suppressing large pulse currents in hybrid vehicle batteries under low-temperature conditions. It is applied to hybrid vehicles equipped with a multi-gear power-split hybrid transmission. The multi-gear power-split hybrid transmission uses a single planetary gear set to achieve power splitting and is configured with a 2x2 AMT (Automated Manual Transmission) for speed and torque adjustment. The control method specifically includes the following steps: Step (1) Build an energy management system An energy management system is established with the vehicle controller (HCU) as the control core. This energy management system also includes a battery and battery management system (BMS), an engine and engine management system (EMS), a motor and motor controller (PEU), and electrical accessories (including a DC-DC converter, an air conditioning compressor (EAC), and an electric air pump (APC). The HCU communicates with the BMS, EMS, PEU, and electrical accessories via CAN (Controller Area Network). Specifically, the HCU receives data from the BMS regarding the battery's maximum allowable discharge power, maximum allowable charging power, operating current, and voltage; the operating voltage and current of the electrical accessories (DC-DC converter, EAC, and APC); the operating speed and torque of motors EM1 and EM2; and the operating speed and torque of the engine. Simultaneously, the HCU can transmit the calculated engine torque and speed requirements, as well as the EM2 motor's torque and speed requirements, to the EMS and PEU via CAN communication to control the engine and motor responses.

[0024] Step (2) Identify the heating / cooling mode like Figure 5 and Figure 6 As shown, after the vehicle is powered on at low voltage and the CAN network is communicating normally, the vehicle controller (HCU) first enters the initialization state, and then receives the maximum allowable discharge power, maximum allowable charging power, and battery temperature information sent by the battery management system (BMS). Based on the above information, it identifies the vehicle's hot / cold engine mode. If the maximum allowable discharge power and maximum allowable charging power of the battery are lower than the set threshold, or if the battery temperature is lower than the set threshold, the vehicle will enter the cold engine mode from the initialization state. If the maximum allowable discharge power and maximum allowable charging power of the battery are higher than the set threshold, or if the battery temperature is higher than the set threshold, the vehicle will enter the warm-up mode from the initialization state.

[0025] Furthermore, the cold engine mode and the hot engine mode can be switched between each other: in the cold engine mode, if the maximum allowable discharge power and the maximum allowable charging power of the battery are higher than the set threshold, or if the battery temperature is higher than the set threshold, the vehicle switches from the cold engine mode to the hot engine mode; after the vehicle is powered off at low voltage, both the cold engine mode and the hot engine mode switch to the initialization state.

[0026] Step (3) Planning the shift sequence The vehicle control unit (HCU) autonomously plans and decides on the corresponding shift sequence based on the identified engine cold / hot mode, and the shift sequence is further subdivided according to whether there is an engine operating requirement: Shift sequence in cold mode: If the engine does not need to work (pure electric mode), the cold engine mode - pure electric gear sequence is used: N0-D4-N0-R4-N0; under this sequence, the vehicle will always remain in D4 gear when driving in D gear, and no gear shifting will be performed; If the engine needs to operate (hybrid mode), the cold engine mode hybrid gear sequence is used: N0-N4-D4-N4-R4-N4-N0; under this sequence, the vehicle will always remain in D4 gear when driving in D gear, and no gear shifting will be performed.

[0027] Shift sequence in warm-up mode: If the engine does not need to work (pure electric mode), the warm engine mode - pure electric gear sequence is used: N0-D1-D3-D4-D3-D1-N0-R1-N0; under this sequence, when the vehicle is driving in D gear, the gear shift can be performed from D1 to D3 to D4 to D3 to D1. If the engine needs to operate (hybrid mode), the hot engine mode hybrid gear sequence is used: N0-N1-D1-D3-D4-D3-D1-N1-R1-N1-N0; under this sequence, when the vehicle is driving in D gear, the gear shift can be performed as D1→D3→D4→D3→D1.

[0028] Step (4) Calculate the torque limit of EM2 motor The vehicle controller (HCU) receives the maximum permissible discharge power and maximum permissible charging power of the battery from the battery management system (BMS), as well as the power consumption of the electrical accessories (calculated based on the operating voltage and current of the electrical accessories) and the actual power of the EM1 motor (the power of the EM1 motor actually reflects the generator power of the engine). It then calculates the maximum permissible drive torque and maximum permissible braking torque of the EM2 motor. like Figure 7 As shown, calculate the maximum allowable drive torque of the EM2 motor: First, based on the maximum allowable discharge power of the battery, the actual power of the EM1 motor, and the power consumed by the electrical accessories, calculate the maximum usable discharge power of the EM2 motor. The calculation formula is: Maximum usable discharge power of the EM2 motor = Maximum allowable discharge power of the battery - (Actual power of the EM1 motor + Power consumed by the electrical accessories). Secondly, combining the efficiency and angular velocity of the EM2 motor (calculated based on the operating speed of the EM2 motor), the maximum usable discharge power of the EM2 motor is converted into the maximum allowable driving torque of the EM2 motor. The specific conversion relationship satisfies: power = torque × angular velocity ÷ efficiency, that is, torque = power × electric efficiency ÷ angular velocity.

[0029] like Figure 8 As shown, calculate the maximum permissible braking torque of the EM2 motor: First, based on the maximum allowable charging power of the battery, the actual power of the EM1 motor, and the power consumed by the electrical accessories, calculate the maximum available charging power of the EM2 motor. The calculation formula is: Maximum available charging power of EM2 motor = maximum allowable charging power of the battery + (actual power of EM1 motor + power consumed by electrical accessories). Secondly, combining the efficiency and angular velocity of the EM2 motor, the maximum available charging power of the EM2 motor is converted into the maximum allowable braking torque of the EM2 motor. The conversion relationship also satisfies: Torque = Power × Power generation efficiency ÷ angular velocity.

[0030] Step (5) Control the EM2 motor torque and battery power The vehicle controller HCU controls the EM2 motor to ensure that its driving torque does not exceed the maximum allowable driving torque and its braking torque does not exceed the maximum allowable braking torque, based on the calculated maximum allowable driving torque and maximum allowable braking torque. Simultaneously, the vehicle controller HCU calculates the required power of the engine and the EM2 motor based on the vehicle's driving power requirements, converting the required power into required torque and required speed, and sends this information to the engine management system (EMS) and the motor controller (PEU) via CAN communication. Ultimately, this strictly limits the real-time power consumption of the battery within the battery's allowable charging and discharging power range, preventing overcharging or over-discharging of the battery.

[0031] As a specific embodiment of this solution, the implementation process is as follows: Application Scenario 1: Cold Engine Mode - Hybrid Driving After the vehicle is powered on at low voltage, the vehicle control unit (HCU) identifies that the vehicle is in cold engine mode based on battery power limits and ambient temperature. It selects the shift sequence for cold engine mode and, based on thermal management's requirements for starting the engine, ultimately selects the cold engine mode hybrid shift sequence: N0-N4-D4-N4-R4. After high voltage power is applied, the gear shift first moves from N0 to N4, where the engine starts and operates. When the driver shifts the gear lever into D, the gear shifts from N4 to D4 and remains in D4 without any further shifting. Compared to the warm engine shift sequence (D1-D3-D4), the cold engine shift sequence maintains a fixed gear without shifting, thus eliminating the large pulse current generated during shifting. By driving in a fixed gear, it avoids instantaneous overcharging and over-discharging of the battery. After the vehicle stops, the driver shifts the gear lever into reverse (R), then from D4 to N4 and finally to R4, maintaining this position while reversing. Simultaneously, the EM2 motor's torque demand is limited to the calculated [EM2 motor maximum available braking torque, EM2 motor maximum available driving torque] limits, and the battery's charging and discharging power is not exceeded.

[0032] Application Scenario 2: Switching from Cold Mode to Hot Mode After the vehicle is powered on at low voltage, the vehicle control unit (HCU) identifies that the vehicle is in cold engine mode based on the battery power limit and ambient temperature. It selects the shift sequence for cold engine mode and, considering the engine starting requirements for thermal management, ultimately selects the cold engine mode-hybrid shift sequence: N0-N4-D4-N4-R4. After the vehicle has been running in D4 gear for a period of time, with the support of thermal management, the battery power limit returns to normal, and the vehicle mode changes from cold engine mode to hot engine mode. D4 gear changes to D4 gear in hot engine mode, and the shift sequence becomes: N0-N1-D1-D3-D4-D3-D1-N1-R1. During the process of the vehicle slowing down to a stop and shifting into reverse (R), the shift route is: D4-D3-D1-N1-R1. During the switching from cold mode to hot mode and the switching of various gears, the torque required by the EM2 motor is always limited within the calculated torque limits of [EM2 motor maximum available braking torque, EM2 motor maximum available driving torque], while the charging and discharging power of the battery is not exceeded.

[0033] Application Scenario 3: Switching from hot mode to cold mode After the vehicle is powered on at low voltage, the vehicle control unit (HCU) identifies that the vehicle is in hot engine mode based on battery power limits and ambient temperature. It selects the gear sequence for hot engine mode. At this time, the engine is faulty and cannot operate, so the vehicle can only operate in pure electric mode. The final selected gear sequence for hot engine mode - pure electric mode is: N0-D1-D3-D4-D3-D1-N0-R1. When driving in D gear, the gear shift route is: D1-D3-D4-D3-D1. Due to the engine's inability to operate, limited thermal management functions, and continuously decreasing battery power, the vehicle mode changes from hot engine mode to cold engine mode. The gear shift sequence changes to the cold engine mode - pure electric mode sequence: N0-D4-N0-R4. The D4 gear has now become the D4 gear in cold engine mode. During the process of the vehicle slowing down to a stop and shifting into R gear, the gear shift route is: D4-N0-R4. During the switching from hot mode to cold mode and the switching of various gears, the torque demand of the EM2 motor is always limited within the calculated torque limits of [EM2 motor maximum available braking torque, EM2 motor maximum available driving torque], while the charging and discharging power of the battery is not exceeded.

[0034] The above description is merely illustrative of the embodiments of the present invention and is not intended to limit the present invention. For those skilled in the art, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A control method for suppressing large pulse currents in hybrid vehicle batteries under low-temperature conditions, characterized in that, Includes the following steps: Step (1): Build an energy management system with the vehicle controller HCU as the control core. The energy management system includes a battery and battery management system (BMS), an engine and engine management system (EMS), a motor and motor controller (PEU), and electrical accessories. The vehicle controller HCU communicates with the battery management system (BMS), the engine management system (EMS), the motor controller (PEU), and the electrical accessories via CAN communication. Step (2): After the vehicle is powered on at low voltage and the CAN network is communicating normally, the vehicle controller HCU receives the maximum allowable discharge power, maximum allowable charging power and battery temperature information sent by the battery management system BMS, and identifies the cold or hot engine mode of the vehicle; if the maximum allowable discharge power and maximum allowable charging power of the battery are lower than the set threshold, or the battery temperature is lower than the set threshold, the vehicle enters the cold engine mode; if the maximum allowable discharge power and maximum allowable charging power of the battery are higher than the set threshold, or the battery temperature is higher than the set threshold, the vehicle enters the hot engine mode. Step (3): The vehicle controller HCU autonomously plans and decides on the corresponding shift sequence based on the identified hot and cold engine modes; Step (4): The vehicle controller HCU receives the maximum allowable discharge power of the battery, the maximum allowable charging power of the battery, the power consumption of the electrical accessories, and the actual power of the EM1 motor from the battery management system BMS, and calculates the maximum allowable driving torque and the maximum allowable braking torque of the EM2 motor respectively. Step (5): The vehicle controller HCU controls the driving torque of the EM2 motor to not exceed the maximum allowable driving torque, and controls the braking torque of the EM2 motor to not exceed the maximum allowable braking torque, thereby limiting the real-time power consumption of the battery to within the allowable charging and discharging power range of the battery.

2. The control method for suppressing large pulse currents in hybrid vehicle batteries under low-temperature conditions according to claim 1, characterized in that, The cold engine mode and the hot engine mode in step (2) can be switched to each other; in the cold engine mode, if the maximum allowable discharge power and the maximum allowable charging power of the battery are higher than the set threshold, or the battery temperature is higher than the set threshold, the vehicle switches from the cold engine mode to the hot engine mode; after the vehicle is powered off at low voltage, both the cold engine mode and the hot engine mode switch to the initialization state.

3. The control method for suppressing large pulse currents in hybrid vehicle batteries under low-temperature conditions according to claim 2, characterized in that, The initialization state mentioned in step (2) is the initial state before the vehicle is powered on at low voltage. After the vehicle is powered on at low voltage, the vehicle controller HCU first enters the initialization state, and then determines whether to enter the cold engine mode or the hot engine mode based on the battery parameters.

4. The control method for suppressing large pulse currents in hybrid vehicle batteries under low-temperature conditions according to claim 1, characterized in that, In step (3), when the vehicle is in cold engine mode, the shift sequence is divided into cold engine mode-pure electric gear sequence and cold engine mode-hybrid gear sequence according to whether there is an engine working requirement; the cold engine mode-pure electric gear sequence is N0-D4-N0-R4-N0; the cold engine mode-hybrid gear sequence is N0-N4-D4-N4-R4-N4-N0.

5. A control method for suppressing large pulse currents in hybrid vehicle batteries under low-temperature conditions according to claim 1 or 4, characterized in that, In step (3), when the vehicle is in hot engine mode, the shift sequence is divided into hot engine mode-pure electric gear sequence and hot engine mode-hybrid gear sequence according to whether there is an engine working requirement; the hot engine mode-pure electric gear sequence is N0-D1-D3-D4-D3-D1-N0-R1-N0; the hot engine mode-hybrid gear sequence is N0-N1-D1-D3-D4-D3-D1-N1-R1-N1-N0.

6. The control method for suppressing large pulse currents in hybrid vehicle batteries under low-temperature conditions according to claim 1, characterized in that, The specific process for calculating the maximum allowable driving torque of the EM2 motor in step (4) is as follows: First, based on the maximum allowable discharge power of the battery, the actual power of the EM1 motor, and the power consumed by the electrical accessories, the maximum usable discharge power of the EM2 motor is calculated. The calculation formula is: Maximum usable discharge power of the EM2 motor = maximum allowable discharge power of the battery - (actual power of the EM1 motor + power consumed by the electrical accessories); Second, combined with the electric efficiency and angular velocity of the EM2 motor, the maximum usable discharge power of the EM2 motor is converted into the maximum allowable driving torque of the EM2 motor.

7. The control method for suppressing large pulse currents in hybrid vehicle batteries under low-temperature conditions according to claim 1, characterized in that, The specific process for calculating the maximum allowable braking torque of the EM2 motor in step (4) is as follows: First, based on the maximum allowable charging power of the battery, the actual power of the EM1 motor, and the power consumed by the electrical accessories, the maximum available charging power of the EM2 motor is calculated. The calculation formula is: Maximum available charging power of the EM2 motor = maximum allowable charging power of the battery + (actual power of the EM1 motor + power consumed by the electrical accessories); Second, combined with the power generation efficiency and angular velocity of the EM2 motor, the maximum available charging power of the EM2 motor is converted into the maximum allowable braking torque of the EM2 motor.

8. The control method for suppressing large pulse currents in hybrid vehicle batteries under low-temperature conditions according to claim 1, characterized in that, The electrical accessories include a DC-DC converter, an air conditioning compressor (EAC), and an electric air pump (APC); the vehicle controller (HCU) receives the operating voltage and current of the DC-DC converter, the air conditioning compressor (EAC), and the electric air pump (APC) to calculate the power consumption of the electrical accessories.

9. The control method for suppressing large pulse currents in hybrid vehicle batteries under low-temperature conditions according to claim 1, characterized in that, The actual power of the EM1 motor reflects the power output of the engine. The vehicle controller HCU receives the operating speed and torque of the EM1 and EM2 motors, as well as the operating speed and torque of the engine. Combining the vehicle's driving power requirements, it calculates the required power of the engine and the required power of the EM2 motor, and converts the required power into required torque and required speed. These are then sent to the engine management system EMS and the motor controller PEU via CAN communication.

10. The control method for suppressing large pulse currents in hybrid vehicle batteries under low-temperature conditions according to claim 1, characterized in that, The low-temperature environment is an environment with a temperature below -5°C. In the low-temperature environment, if the control method is not executed, when the vehicle shifts gears, the battery will experience instantaneous overcharging or over-discharging, with instantaneous over-limit power exceeding 10kW.

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