A control method for avoiding overcharging of a hybrid vehicle battery in a low temperature environment
By regulating the engine's power generation and battery current in a closed loop, and combining generator and engine control, the problem of overcharging of hybrid vehicle batteries in low-temperature environments is solved, ensuring normal vehicle operation and stable driving.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WUHAN LINCONTROL AUTOMOTIVE ELECTRONICS CO LTD
- Filing Date
- 2023-06-08
- Publication Date
- 2026-05-19
AI Technical Summary
In low-temperature environments, hybrid vehicle batteries are prone to overcharging, which can render the vehicle inoperable. Existing control solutions sacrifice driving capability to avoid this malfunction.
By adjusting the engine's power generation through a closed-loop system, and combining the actual battery current with the driver's needs, the operating status of the generator and engine is controlled to prevent battery overcharging. When necessary, a water-heated electric heater is used to raise the temperature, ensuring the engine operates normally.
In low-temperature environments, it avoids battery overcharging malfunctions, ensures normal vehicle operation and stable driving, prevents vehicle vibration, and improves the stability of vehicle control.
Smart Images
Figure CN116691649B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of automotive batteries, and more specifically to a control method for preventing overcharging of hybrid vehicle batteries in low-temperature environments. Background Technology
[0002] As hybrid vehicles develop rapidly, their share of car sales is also increasing.
[0003] High, but with energy shortages, people's demands for driving environment, driving pleasure and intelligence...
[0004] The demand for driving and other activities is also increasing.
[0005] However, when existing hybrid vehicles operate in extremely low temperature environments, the battery temperature is very low and the battery discharge power is also very small. Therefore, the engine needs to generate electricity to cooperate with the battery discharge in order to ensure normal driving and heating.
[0006] However, during the control process, the battery often reports an overcharge fault due to the limited charging capacity of the battery and the imperfect vehicle control, which affects normal driving.
[0007] Specifically, when the vehicle is in a low-temperature environment, such as when the ambient temperature is below -20°C and the battery temperature is below -20°C, the battery charging power is 0kW, meaning the battery is not allowed to charge. If the battery is forcibly charged, it will report an overcharge fault after more than 2 seconds, and a high voltage will be applied, causing the entire vehicle to become inoperable.
[0008] When the battery discharge power is less than 30kW and the engine is running, during the acceleration process when the driver presses the accelerator, the intake air density is higher than normal due to the low temperature environment, which causes the engine controller to generate more power. When the actual power generation of the engine controller is greater than the requested power generation of the engine controller, the excess power generation will be charged into the battery. However, if the charging exceeds 2 seconds, the battery will report an overcharge fault, and the whole vehicle will enter a low-voltage condition. Under the low-voltage condition, the whole vehicle cannot be driven.
[0009] Current common control schemes prevent battery malfunctions by limiting power and driving range, but this comes at the cost of reduced driving capability.
[0010] Therefore, there is an urgent need for a method that can ensure the stable operation of the battery while also ensuring the normal operation of the vehicle. Summary of the Invention
[0011] The purpose of this invention is to overcome the shortcomings of the above background and to propose a control method for avoiding overcharging of hybrid vehicle batteries in low-temperature environments, which can prevent the battery from becoming overcharged.
[0012] The objective of this invention is achieved through the following technical solution: a control method for preventing overcharging of a hybrid vehicle battery in low-temperature environments. When the ambient temperature is below -20°C and the battery temperature is below -20°C, it includes the following control steps: when the battery discharge power is greater than 30kW, the engine runs.
[0013] ① When the car is accelerating, the battery is used to discharge first. When the battery discharge power is insufficient, the engine generates electricity to supplement the insufficient part. The closed-loop regulation is performed according to the actual current of the battery to regulate the power generation of the engine.
[0014] I. When the actual current of the battery is less than the lower limit of the overcharge safety threshold, reduce the generator power.
[0015] II. When the actual current of the battery is greater than the upper limit of the overcharge safety threshold, increase the generator power of the engine.
[0016] III. When the actual current of the battery is between the lower limit of the overcharge safety threshold and the upper limit of the overcharge safety threshold, the engine power generation remains at the requested value.
[0017] In the above technical solution: when the battery discharge power is [3kW, 30kW], the engine generates electricity to control the drive motor;
[0018] ① Control method: Closed-loop regulation control is performed based on the actual current of the battery. The maximum power generation limit of the engine is calculated as the sum of the driver's requested drive power and the air conditioning power minus the battery discharge power.
[0019] ② The target control current of the battery is preset and is located within the overcharge safety threshold. The generator power is adjusted based on the actual battery current.
[0020] I. When the actual current of the battery is less than the lower limit of the overcharge safety threshold, reduce the power generation.
[0021] II. When the actual current of the battery exceeds the upper limit of the overcharge safety threshold, increase the power generation.
[0022] III. When the actual current of the battery is between the lower limit of the overcharge safety threshold and the upper limit of the overcharge safety threshold, the engine power generation remains at the requested value.
[0023] In the above technical solution: when the battery discharge power is <3kW, generator voltage regulation control is adopted, which includes generator controller voltage regulation control and engine speed control.
[0024] In the above technical solution: generator controller voltage regulation control:
[0025] The vehicle controller sends a voltage regulation control flag to the generator controller. When the generator controller receives the voltage regulation control flag, it enters the voltage regulation control mode.
[0026] At the same time, the vehicle controller sends a power request to the generator controller. The generator controller, based on the control phase current and magnetic field, ensures that the voltage is stable at the target value while meeting the power request of the vehicle controller.
[0027] In the above technical solution: Engine speed control:
[0028] The vehicle controller sends a speed control flag to the engine controller. When the engine controller receives the speed control flag, it enters the engine speed control mode.
[0029] At the same time, the vehicle controller sends a target speed to the engine controller, and the engine controller adjusts the actual speed within the target speed range based on the controlled engine torque.
[0030] In the above technical solution: when the car is decelerating by releasing the accelerator, the vehicle controller requests a reduction in torque due to the response of the engine controller. However, the 0 torque request will be 100ms-300ms slower. At this time, the vehicle controller sends a 0 torque request and a shutdown request at the same time. The engine controller responds directly to the shutdown. After the engine is turned off, the vehicle controller requests to start running again in the 0 torque condition.
[0031] In the above technical solution: when the ambient temperature is below -20℃, the engine runs when the car is started, and the water heater is pre-activated.
[0032] When a hybrid vehicle is in an extremely low-temperature environment, the engine runs, and because the ambient temperature is low, the intake air density is higher than that at normal temperature. This causes the engine controller to generate more power than normal, and the excess power will charge the battery, resulting in overcharging.
[0033] The present invention has the following advantages: 1. The vehicle controller in the present invention calculates the power generation in real time according to the power demand of the driver. Under the condition that there is no battery overcharging problem, the generator controller generates power to drive the drive motor to drive the wheels, ensuring that the vehicle can have power output and meet the driving capacity.
[0034] 2. This invention avoids battery overcharging by setting the vehicle controller and solves the vehicle vibration problem caused by rapid torque reduction, thus ensuring stable driving of the vehicle during operation. Attached Figure Description
[0035] Figure 1 is a specific control flowchart of the present invention. Detailed Implementation
[0036] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, these descriptions do not constitute a limitation of the present invention and are merely illustrative. The advantages of the present invention will become clearer and easier to understand through this description.
[0037] Referring to Figure 1: A control method for preventing overcharging of a hybrid vehicle battery in low-temperature environments, when the ambient temperature is below -20 degrees Celsius and the battery temperature is below -20 degrees Celsius, includes the following control steps: when the battery discharge power is greater than 30 kW, the engine runs.
[0038] ① When the car is accelerating, the battery is used to discharge first. When the battery discharge power is insufficient, the engine generates electricity to supplement the insufficient part. The closed-loop regulation is performed according to the actual current of the battery to regulate the power generation of the engine.
[0039] I. When the actual current of the battery is less than the lower limit of the overcharge safety threshold, reduce the engine's power generation; the minimum power generation of the engine can be adjusted to 0.
[0040] II. When the actual current of the battery is greater than the upper limit of the overcharge safety threshold, increase the generator power of the engine; the increased generator power can increase the maximum generator power of the large engine.
[0041] III. When the actual current of the battery is between the lower limit and the upper limit of the overcharge safety threshold, the generator power output remains at the requested value and the generator power output is not adjusted through closed-loop regulation.
[0042] When the battery discharge power is [3kW, 30kW], the engine generates electricity to control the drive motor.
[0043] ① Control method: Closed-loop regulation control is performed based on the actual current of the battery. The maximum power generation limit of the engine is calculated as the sum of the driver's requested drive power and the air conditioning power minus the battery discharge power.
[0044] ② Pre-set the target control current for the battery. The target control current is within the overcharge safety threshold range. The generator power is adjusted based on the actual battery current. The battery overcharge safety threshold is the current value at which the battery is overcharged, and it is usually a range.
[0045] I. When the actual current of the battery is less than the lower limit of the overcharge safety threshold, reduce the power generation. The minimum power generation of the engine can be adjusted to 0.
[0046] II. When the actual current of the battery is greater than the upper limit of the overcharge safety threshold, the power generation capacity is increased. The increased power generation capacity of the engine can increase the maximum power generation capacity of the large engine.
[0047] III. When the actual current of the battery is between the lower limit and the upper limit of the overcharge safety threshold, the generator power output remains at the requested value and the generator power output is not adjusted through closed-loop regulation.
[0048] When the battery discharge power is <3kW, generator voltage regulation control is adopted. The generator voltage regulation control includes generator controller voltage regulation control and engine controller. The generator controller is used for generator power generation control, and the engine controller is used for engine fuel injection ignition, torque and speed control.
[0049] Generator controller voltage regulation control:
[0050] The vehicle controller sends a voltage regulation control flag to the generator controller. When the generator controller receives the voltage regulation control flag, it enters the voltage regulation control mode.
[0051] At the same time, the vehicle controller sends a power request to the generator controller. The generator controller, based on the control phase current and magnetic field, ensures that the voltage is stable at the target value while meeting the power request of the vehicle controller.
[0052] Engine controller:
[0053] The vehicle controller sends a speed control flag to the engine controller. When the engine controller receives the speed control flag, it enters the engine speed control mode.
[0054] At the same time, the vehicle controller sends a target speed to the engine controller, and the engine controller adjusts the actual speed within the target speed range based on the controlled engine torque.
[0055] When a car is decelerating by releasing the accelerator, the vehicle controller requests a reduction in torque due to the response of the engine controller. However, the 0 torque request will be delayed by 100ms-300ms. Therefore, during this time, there will be a problem of the engine generating excess electricity to charge the battery. (The excess electricity is the engine's actual electricity generation minus the requested engine electricity generation = excess electricity generation.)
[0056] At this time, the vehicle controller sends a 0 torque request and a shutdown request. The engine controller responds directly to the shutdown. After the engine is turned off, the vehicle controller requests to start running in the 0 torque condition again.
[0057] When the ambient temperature is below -20℃ and the car is started, the water heater is forcibly turned on in order to quickly raise the engine coolant temperature. If there is no heating request in the passenger compartment, the battery is heated instead (the water heater is used to heat the water in the heating circuit for heating the passenger compartment or battery).
[0058] Example 1: When the vehicle is in a low-temperature environment, such as when the ambient temperature is below -20°C and the battery temperature is below -20°C, the battery charging power is 0kW, meaning the battery is not allowed to charge. If the battery is forcibly charged, after more than 2 seconds, the battery will report an overcharge fault and a high voltage will be applied, making the vehicle unable to move.
[0059] When the battery discharge power is less than 30kW and the engine is running, when the hybrid vehicle is in an extremely low temperature environment, during the acceleration process when the driver presses the accelerator, the density of the intake air is greater than that at normal temperature (i.e., the density of the cold air entering the engine is greater than that of the air entering the engine at normal temperature). This causes the engine controller to generate more power, and the excess power will charge the battery and cause overcharging.
[0060] 1. When the battery discharge power is <3kW, generator voltage regulation control is adopted. Generator voltage regulation control includes two forms: generator controller voltage regulation control and engine controller control.
[0061] 1.1 Generator Controller Voltage Stabilization Control: The vehicle controller sends a voltage stabilization control flag to the generator controller. Upon receiving the flag, the generator controller enters the voltage stabilization control mode. Simultaneously, the vehicle controller sends a power request to the generator controller. The generator controller, based on the control phase current and magnetic field, ensures the voltage remains stable at the target value while simultaneously fulfilling the power request from the vehicle controller.
[0062] 1.2 Engine Speed Control: The vehicle controller sends a speed control flag to the engine controller. When the engine controller receives the speed control flag, it enters the engine speed control mode. At the same time, the vehicle controller sends a target speed to the engine controller. The engine controller adjusts the actual speed within the target speed range according to the controlled engine torque.
[0063] 2. When the battery discharge power is [3kW, 30kW], the engine generates electricity to control the drive motor.
[0064] Control method: Closed-loop regulation control based on the actual current of the battery.
[0065] 2.1 The maximum power generation limit of the engine is calculated as the sum of the driver's requested drive power, air conditioning power, and battery discharge power.
[0066] 2.2 Set the target control current for the battery, for example, 3A-5A;
[0067] 2.3 Adjust the engine's power generation by controlling the actual battery current;
[0068] 2.3.1 When the actual current of the battery is <3A, reduce the power generation, and reduce the minimum value to 0;
[0069] 2.3.2 When the actual current of the battery is greater than 5A, the power generation capacity is increased, and the maximum value is increased to the maximum power generation capacity limit of the engine;
[0070] 2.3.3 When the actual current of the battery is between [3A, 5A], the power generation remains at the requested value, and the power generation of the generator is not adjusted through closed-loop regulation.
[0071] The parts not described in detail above are all existing technologies.
Claims
1. A control method for preventing overcharging of a hybrid vehicle battery in a low-temperature environment, characterized in that: when the ambient temperature is less than -20 degrees Celsius and the battery temperature is less than -20 degrees Celsius, the method is as follows: It includes the following control steps: when the battery discharge power is greater than 30kW, the engine starts. ① When the car is accelerating, the battery is used to discharge first. When the battery discharge power is insufficient, the engine generates electricity to supplement the insufficient part. The closed-loop regulation is performed according to the actual current of the battery to regulate the power generation of the engine. I. When the actual current of the battery is less than the lower limit of the overcharge safety threshold, reduce the generator power. II. When the actual current of the battery is greater than the upper limit of the overcharge safety threshold, increase the generator power of the engine. III. When the actual current of the battery is between the lower limit of the overcharge safety threshold and the upper limit of the overcharge safety threshold, the engine power generation remains at the requested value. When the car is decelerating by releasing the accelerator, the vehicle controller requests a reduction in torque due to the response of the engine controller. However, the 0 torque request will be 100ms-300ms slower. At this time, the vehicle controller sends a 0 torque request and a shutdown request at the same time. The engine controller responds directly to the shutdown. After the engine is turned off, the vehicle controller requests to start running again in the 0 torque condition.
2. The control method for preventing overcharging of hybrid vehicle batteries in low-temperature environments according to claim 1, characterized in that... When the battery discharge power is [3kW, 30kW], the generator output is used to control the drive motor. ① Control method: Closed-loop regulation control is performed based on the actual current of the battery. The maximum power generation limit of the engine is calculated as the sum of the driver's requested drive power and the air conditioning power minus the battery discharge power. ② The target control current of the battery is preset and is located within the overcharge safety threshold. The generator power is adjusted based on the actual battery current. I. When the actual current of the battery is less than the lower limit of the overcharge safety threshold, reduce the power generation. II. When the actual battery current exceeds the overcharge safety threshold, increase the power generation capacity. III. When the actual current of the battery is between the lower limit of the overcharge safety threshold and the upper limit of the overcharge safety threshold, the engine power generation remains at the requested value.
3. The control method for preventing overcharging of hybrid vehicle batteries in low-temperature environments according to claim 2, characterized in that: When the battery discharge power is <3kW, generator voltage regulation control is adopted, which includes generator controller voltage regulation control and engine speed control.
4. The control method for preventing overcharging of hybrid vehicle batteries in low-temperature environments according to claim 3, characterized in that: Generator controller voltage regulation control: The vehicle controller sends a voltage regulation control flag to the generator controller. When the generator controller receives the voltage regulation control flag, it enters the voltage regulation control mode. At the same time, the vehicle controller sends a power request to the generator controller. The generator controller, based on the control phase current and magnetic field, ensures that the voltage is stable at the target value while meeting the power request of the vehicle controller.
5. The control method for preventing overcharging of a hybrid vehicle battery in a low-temperature environment according to claim 4, characterized in that: Engine speed control: The vehicle controller sends a speed control flag to the engine controller. When the engine controller receives the speed control flag, it enters the engine speed control mode. At the same time, the vehicle controller sends a target speed to the engine controller, and the engine controller adjusts the actual speed within the target speed range based on the controlled engine torque.
6. The control method for preventing overcharging of a hybrid vehicle battery in a low-temperature environment according to claim 5, characterized in that... When the ambient temperature is below -20℃, the engine starts running when the car is started, and the water heater is pre-activated.