WO2022022273A1

WO2022022273A1 - Battery soc management method for hybrid electric vehicle

Info

Publication number: WO2022022273A1
Application number: PCT/CN2021/105893
Authority: WO
Inventors: 尹建坤; 梁赫奇; 刘建康; 马艳红; 李川
Original assignee: 中国第一汽车股份有限公司
Priority date: 2020-07-28
Filing date: 2021-07-13
Publication date: 2022-02-03
Also published as: CN111845703A

Abstract

A battery SOC management method for a hybrid electric vehicle, the method comprising: acquiring the temperature of a battery, and determining the current SOC upper limit value and the current SOC lower limit value of the battery according to the temperature; determining an SOC median value according to the SOC upper limit value and the SOC lower limit value; determining a battery SOC management limit value according to the SOC median value; and performing vehicle power distribution according to the battery SOC management limit value.

Description

Battery SOC Management Method for Hybrid Electric Vehicles

This application claims the priority of the Chinese patent application with application number 202010737828.0 filed with the China Patent Office on July 28, 2020, the entire contents of which are incorporated herein by reference.

technical field

The embodiments of the present application relate to the hybrid electric vehicle technology, for example, to a battery state of charge (State Of Charge, SOC) management method of the hybrid electric vehicle.

Background technique

A hybrid vehicle includes a motor drive system and an engine drive system. The driving power of a hybrid vehicle is provided by a single drive system independently or provided by two drive systems according to the actual vehicle driving state. Through the motor drive system, a hybrid vehicle can be driven. It realizes functions such as idle shutdown, auxiliary drive and regenerative braking energy recovery.

The battery is an important part of the motor drive system. The battery can be used as the energy source of the motor drive system to output electric energy to the outside, and can also be used to store the electric energy generated when the motor is in the charging mode. How to manage the SOC of the battery in the vehicle system? It is the key point of vehicle hybrid control.

SUMMARY OF THE INVENTION

The present application provides a battery SOC management method for a hybrid electric vehicle, which improves the working efficiency of the battery, prolongs the service life of the battery and improves the economy of the whole vehicle.

An embodiment of the present application provides a battery SOC management method for a hybrid electric vehicle, including: collecting a temperature of a battery, and determining a current upper SOC value and a lower SOC value of the battery according to the temperature; value and the SOC lower limit value, determine the SOC median value; determine the battery SOC management limit value according to the SOC median value, and perform vehicle power distribution according to the battery SOC management limit value.

Optionally, the SOC management limit value includes an on-board power generation SOC value, and the on-board power generation SOC value is used to perform the vehicle power distribution when the vehicle is in an engine driving mode.

Optionally, the SOC management limit value includes a regenerative braking SOC value, and the regenerative braking SOC value is used to perform the vehicle power distribution when the vehicle is in a stop coasting mode.

Optionally, the SOC management limit value includes a pure electric SOC value, and the pure electric SOC value is used to perform the vehicle power distribution when the vehicle is in a battery driving mode.

Optionally, the SOC management limit value includes an assist SOC value, and the assist SOC value is used to perform the vehicle power distribution when the vehicle is in a hybrid drive mode.

Optionally, the collecting the temperature of the battery, and determining the upper limit value of SOC and the lower limit value of SOC of the battery according to the temperature, includes: determining a temperature range in which the battery is located according to the temperature, and according to the temperature The interval determines the current SOC upper limit value, SOC lower limit value and SOC median value of the battery.

Optionally, performing vehicle power distribution based on the on-board power generation SOC value includes: collecting the current SOC value of the battery, and in the case that the SOC value is less than the on-board power generation SOC value, controlling the battery to collect engine output excess power.

Optionally, the performing vehicle power distribution according to the battery SOC management limit value includes: collecting the SOC value of the battery, and controlling the battery when the SOC value is greater than the regenerative braking SOC value. It is forbidden to collect inertial power when the vehicle is coasting.

Optionally, the performing the vehicle power distribution according to the battery SOC management limit includes: collecting the SOC value of the battery, and controlling the vehicle to prohibit the vehicle from being in any state when the SOC value is less than the pure electric SOC value. battery-driven mode.

Optionally, the performing the vehicle power distribution according to the battery SOC management limit includes: collecting the SOC value of the battery, and controlling the vehicle to prohibit the vehicle from being in the Hybrid drive mode.

Description of drawings

1 is a flowchart of a battery SOC management method for a hybrid electric vehicle in an embodiment;

2 is a structural block diagram of a parallel hybrid configuration in an embodiment;

3 is a structural block diagram of a power coupling configuration in an embodiment;

4 is a schematic diagram of a battery SOC management limit in an embodiment;

FIG. 5 is a characteristic curve diagram of the engine in the embodiment.

detailed description

The present application will be described below with reference to the accompanying drawings and embodiments. It should be understood that the embodiments described herein are only used to explain the present application, but not to limit the present application. For convenience of description, the drawings only show some but not all structures related to the present application.

FIG. 1 is a flowchart of a battery SOC management method for a hybrid electric vehicle in an embodiment. Referring to FIG. 1 , the battery SOC management method for a hybrid electric vehicle includes the following steps.

S1. Collect the temperature of the battery, and determine the current SOC upper limit value, SOC lower limit value and SOC median value of the battery according to the temperature.

Exemplarily, in this step, the temperature of the battery may be collected through a vehicle control unit (Vehicle control unit, VCU). Exemplarily, the temperature of the battery can be collected once in each cycle according to a set time interval, and the upper limit value of SOC, the lower limit value of SOC and the median value of SOC can be determined according to the battery temperature collected in each cycle; it can also be collected in real time. The temperature of the battery, determine the temperature range, determine the SOC upper limit, SOC lower limit and SOC median value according to the temperature range, so as to avoid unnecessary judgment and calculation, so that the VCU can generate an effective control strategy, and can also reduce Small VCU workload.

Exemplarily, the SOC upper limit value refers to the SOC limit value at which charging cannot be continued at the current temperature, and the SOC lower limit value refers to the SOC limit that cannot continue discharging at the current temperature. The median SOC value can be the average value calculated according to the SOC upper limit value and the SOC lower limit value, or it can be adapted to the current SOC upper limit value and SOC lower limit value, located between the SOC upper limit value and the SOC lower limit value. SOC value between.

Exemplarily, in this step, the upper limit value of SOC, the lower limit value of SOC and the median value of SOC may be determined according to the collected battery temperature by means of fuzzy control, or the SOC may be determined according to a preset temperature-SOC value curve (for example, a MAP map). Lower limit value, SOC upper limit value and SOC median value.

S2. Determine the battery SOC management limit based on the median SOC value.

Exemplarily, in this embodiment, the SOC management limit value includes multiple SOC values, wherein different SOC management limit values can be obtained according to a set rule, for example, by shifting the SOC median value up and down.

In different driving modes, such as engine driving mode, battery driving mode or hybrid power mode, the vehicle controller can generate a battery control strategy for the driving mode according to the SOC value corresponding to the driving mode, and then carry out the power consumption of the vehicle. distribute.

S3. Vehicle power distribution is performed according to the battery SOC management limit.

Exemplarily, in this step, the vehicle controller performs power distribution to the vehicle in a specific driving mode according to a predetermined battery control strategy.

In this embodiment, the battery SOC management method adopts the battery SOC management limit, and the vehicle power distribution is carried out according to the battery SOC management limit, which can ensure that the battery is not overcharged or overdischarged, and the power battery can give full play to the hybrid power. The auxiliary adjustment function of the vehicle model to the main power source (when the main power source is insufficient, the main power source is supplemented to meet the needs of the whole vehicle; when the main power source is surplus, the excess power of the main power source is absorbed, and the braking energy recovery of the vehicle is carried out). The working efficiency of the battery can prolong the service life of the battery, thereby improving the economy of the whole vehicle.

In this embodiment, the battery SOC management method for a hybrid electric vehicle can be applied to hybrid electric vehicles such as a parallel hybrid configuration and a power coupling configuration.

FIG. 2 is a structural block diagram of the parallel hybrid configuration in the embodiment. Referring to FIG. 2 , the parallel hybrid configuration includes a motor 300 with an electric motor/generating function, and the motor 300 is connected to the engine 200 through a torque coupler 400 . The engine 200 is the main power source, the motor 300 is connected with the battery 100 to form a motor-battery system, the motor-battery system is the secondary power source, and the torque coupler 400 can couple the torque of the engine 200 and the motor 300 to output.

FIG. 3 is a structural block diagram of the power coupling configuration in the embodiment. Referring to FIG. 3 , the power coupling configuration includes a second electric motor E2 with an electric motor/generating function, and the second electric motor E2 is mechanically connected with the engine 200 to form an engine-generator system , the engine-generator system is the main power source, the battery 100 is the auxiliary power source, and the first motor E1 simultaneously receives power input from the main power source and the auxiliary power source, and outputs torque.

In the above hybrid models, the whole vehicle can be driven by an engine alone, a battery alone, or an engine-battery hybrid drive, and the vehicle has an engine drive mode, a battery drive mode, and a hybrid drive mode.

FIG. 4 is a schematic diagram of a battery SOC management limit in an embodiment. Referring to FIG. 4 , in this embodiment, the SOC management limit value includes the on-vehicle power generation SOC value, and the on-vehicle power generation SOC value is used for vehicle power distribution when the vehicle is in the engine driving mode. Exemplarily, the SOC value of on-board power generation is obtained by shifting the median SOC value upward by Th3.

As an optional implementation, the vehicle power distribution based on the SOC value of on-board power generation includes: collecting the current SOC value of the battery, and if the SOC value is less than the on-board power generation SOC value, controlling the battery to collect excess power output by the engine.

FIG. 5 is a characteristic curve diagram of the engine in the embodiment. 4 and 5, exemplarily, when the vehicle is in the engine driving mode, if the driver's demand torque is in the optimal engine economy curve, and the current SOC value of the battery is lower than the SOC value of the on-board power generation, the vehicle control The controller controls the engine to work on the optimal working curve, and the part of the torque generated by the engine that exceeds the driver's demand is used to drive the motor, so that the motor is in the charging mode, and the battery is charged through the motor. Exemplarily, the SOC value of on-board power generation represents the maximum SOC value that the battery can achieve by absorbing excess power other than the driver's required power from the main power source through the motor. When the SOC value of the battery is higher than the on-board power generation SOC threshold, it will During the driving process of the vehicle, it is forbidden to charge the excess power of the main power source into the battery. When the SOC value of the battery gradually approaches the SOC value of the driving power generation, the excess power that the battery can receive gradually decreases. The difference between the power generation SOC values is used to distribute excess power.

The SOC management limit also includes a regenerative braking SOC value, which is used for vehicle power distribution when the vehicle is in a stop coasting mode.

As an optional implementation, the vehicle power distribution by using the regenerative braking SOC value includes: collecting the current SOC value of the battery, and if the SOC value is greater than the regenerative braking SOC value, controlling the battery to prohibit the collection of inertial power when the vehicle is coasting. Referring to FIG. 4 , exemplarily, the SOC value for regenerative braking is obtained by shifting the median SOC value upward by Th4.

Exemplarily, the regenerative braking SOC value represents the maximum SOC value that can be reached by the battery absorbing the inertial power generated by the motor during the braking and coasting process of the vehicle. When the SOC value of the battery is higher than the regenerative braking SOC value, it is During the driving process, the battery is prohibited from performing energy recovery. When the battery SOC value gradually approaches the regenerative braking SOC value, the inertial power that the battery can receive gradually decreases. The difference is used to distribute the inertial power.

The SOC management limit also includes the pure electric SOC value. The pure electric SOC value is used to distribute the power of the whole vehicle when the vehicle is in the battery drive mode.

As an embodiment, the power distribution of the whole vehicle by the pure electric SOC value includes: collecting the current SOC value of the battery, and if the SOC value is less than the pure electric SOC value, controlling the vehicle to prohibit the battery driving mode. Exemplarily, referring to FIG. 4 , the pure electric SOC value is obtained by shifting the SOC median value downward by Th2. Exemplarily, the pure electric SOC value represents the minimum SOC limit when the battery maintains the vehicle in the battery driving mode. When the current SOC value of the battery is lower than the pure electric SOC value, the vehicle controller controls the vehicle to be in the engine driving mode or the hybrid vehicle. drive mode.

The SOC management limit also includes the assist SOC value, which is used to distribute the power of the entire vehicle when the vehicle is in the hybrid drive mode.

As an embodiment, the power distribution of the whole vehicle by the assist SOC value includes: collecting the current SOC value of the battery, and if the SOC value is less than the assist SOC value, controlling the vehicle to prohibit the hybrid drive mode. Exemplarily, referring to FIG. 4 , the boost SOC value is obtained by shifting the median SOC value downward by Th5.

4 and 5, exemplarily, the assist SOC value represents the lowest battery SOC value when the battery can be used as a secondary power source, if the current SOC value of the battery is greater than the assist SOC value, and the driver's required torque is at the maximum external characteristic of the engine When the curve is above, the vehicle controller controls the battery and the motor to provide torque that the engine cannot provide to meet the driving needs. When the current SOC value of the battery is lower than the assist SOC value, the vehicle controller prohibits the battery-motor as a secondary controller. power source. When the battery SOC value is gradually approaching the assist SOC value, the assist power provided by the battery gradually decreases, and the vehicle controller allocates assist power according to the difference between the current SOC value of the battery and the assist SOC value.

As an alternative, in this embodiment, the offsets Th2, Th3, Th4, and Th5 are obtained through calibration tests. During the calibration test, one battery temperature corresponds to a set of SOC upper limit value, SOC lower limit value, and SOC middle value. value, Th2, Th3, Th4 and Th5. Exemplarily, when determining the battery temperature, the battery life can be used as a standard to determine the SOC upper limit value and the SOC lower limit value, and the average value of the SOC upper limit value and the SOC lower limit value can be used as the SOC median value. Determine the depth of discharge (Depth Of Discharge, DOD), and then calculate the offset according to the depth of discharge. The formula used is:

Th2=DOD*K1; Th3=DOD*K2; Th4=DOD*K3; Th5=DOD*K4

In the formula, K1, K2, K3, and K4 are the bias coefficients, K1, K2, K3, and K4 are the fixed values configured during the calibration test, and the value of the bias coefficient is less than 1.

In this embodiment, the battery SOC management limit includes the driving power generation SOC value, the regenerative braking SOC value, the pure electric SOC value, and the power assist SOC value. Under the premise of charging and over-discharging, the working curve of the engine is as close as possible to the optimal curve of the engine's economy, so as to improve the economy of the whole vehicle.

Claims

A battery state-of-charge SOC management method for a hybrid electric vehicle, comprising:

collecting the temperature of the battery, and determining the upper limit value of SOC and the lower limit value of SOC of the battery according to the temperature;

determining a median SOC value according to the SOC upper limit value and the SOC lower limit value;

The battery SOC management limit is determined according to the SOC median value, and the vehicle power distribution is performed according to the battery SOC management limit.
The battery SOC management method for a hybrid electric vehicle according to claim 1, wherein the SOC management limit value includes a driving power generation SOC value,

The on-board power generation SOC value is used to perform the vehicle power distribution when the vehicle is in an engine driving mode.
The battery SOC management method for a hybrid electric vehicle according to claim 1, wherein the SOC management limit value includes a regenerative braking SOC value,

The regenerative braking SOC value is used to perform the vehicle power distribution when the vehicle is in a stop coasting mode.
The battery SOC management method of a hybrid electric vehicle according to claim 1, wherein the SOC management limit includes a pure electric SOC value,

The pure electric SOC value is used to perform the vehicle power distribution when the vehicle is in a battery driving mode.
The battery SOC management method for a hybrid electric vehicle according to claim 1, wherein the SOC management limit value includes a booster SOC value,

The boost SOC value is used to perform the vehicle power distribution when the vehicle is in a hybrid drive mode.
The battery SOC management method for a hybrid electric vehicle according to claim 1, wherein the collecting the temperature of the battery and determining the upper limit value and lower limit value of the SOC of the battery according to the temperature comprises:

determining the temperature range in which the battery is located according to the temperature;

The SOC upper limit value and the SOC lower limit value of the battery are determined according to the temperature interval.
The battery SOC management method for a hybrid electric vehicle according to claim 2, wherein the performing the vehicle power distribution according to the battery SOC management limit comprises:

The SOC value of the battery is collected, and when the SOC value is smaller than the SOC value of the on-board power generation, the battery is controlled to collect excess power output by the engine.
The battery SOC management method for a hybrid electric vehicle according to claim 3, wherein the performing the vehicle power distribution according to the battery SOC management limit comprises:

The SOC value of the battery is collected, and when the SOC value is greater than the regenerative braking SOC value, the battery is controlled to prohibit the collection of inertial power when the vehicle is coasting.
The battery SOC management method for a hybrid electric vehicle according to claim 4, wherein the performing the vehicle power distribution according to the battery SOC management limit comprises:

The SOC value of the battery is collected, and when the SOC value is smaller than the pure electric SOC value, the vehicle is controlled to prohibit being in the battery driving mode.
The battery SOC management method for a hybrid electric vehicle according to claim 5, wherein the performing the vehicle power distribution according to the battery SOC management limit value comprises:

The SOC value of the battery is collected, and when the SOC value is smaller than the booster SOC value, the vehicle is controlled to prohibit the hybrid driving mode.