阅读说明：本技术 一种电动车制动能量回收和滑行能量回收协调控制的方法 (Method for coordinately controlling braking energy recovery and sliding energy recovery of electric vehicle ) 是由 张红燕 杨庚 白鹍鹏 王雷 马志国 李遵涛 姚诚 王秀颖 于 2021-07-16 设计创作，主要内容包括：本发明属于车辆能量回收技术领域,具体涉及一种电动车制动能量回收和滑行能量回收协调控制方法；当车辆稳定时,IBC将滑行能量回收扭矩值+制动能量回收扭矩值作为整车需要回收的扭矩值传输给VCU,当能量回收退出(最大可回收的扭矩值变小或者前轴失稳)时,IBC协调前轴能量回收和前后轴的液压制动,控制能量回收退出,制动液压相应增加,保证整车的减速度不变以及车辆稳定性,同时最大限度的能量回收。(The invention belongs to the technical field of vehicle energy recovery, and particularly relates to a coordinated control method for braking energy recovery and sliding energy recovery of an electric vehicle; when the vehicle is stable, the IBC transmits the sliding energy recovery torque value and the braking energy recovery torque value as torque values required to be recovered by the whole vehicle to the VCU, and when the energy recovery exits (the maximum recoverable torque value is reduced or the front axle is unstable), the IBC coordinates the energy recovery of the front axle and the hydraulic braking of the front axle and the rear axle, controls the energy recovery to exit, correspondingly increases the braking hydraulic pressure, ensures the deceleration of the whole vehicle to be unchanged and the stability of the vehicle, and simultaneously recovers the energy to the maximum extent.)

1. A method for coordinately controlling sliding energy recovery and braking energy recovery of an electric vehicle is characterized by comprising the following steps:

the following three cases are distinguished:

in the first case: the IBC calculates the torque value of the whole vehicle needing to be recovered according to the following formula:

the torque value required to be recovered by the whole vehicle is the sliding energy recovery torque value plus the braking energy recovery torque value;

in the second case: the whole vehicle has instability tendency, but the maximum recoverable torque is enough

When the whole vehicle has instability tendency, wheels have locking tendency and are divided into two working conditions: the driver steps on the brake and the driver does not step on the brake; when a driver does not tread on the brake, the IBC performs PID control according to the slip rate of the front wheels of the vehicle, namely the torque value needing to be recovered by the whole vehicle transmitted to the VCU by the IBC is lower than the sliding energy recovery torque value, and the larger the slip rate of the front wheels of the vehicle is, the lower the torque value needing to be recovered by the whole vehicle transmitted to the VCU by the IBC is, so as to ensure that the vehicle is in a stable state;

when a driver steps on the brake, the IBC performs PID control according to the four-wheel slip rate, namely the torque value needing to be recovered of the whole vehicle transmitted to the VCU by the IBC is lower than the torque value needing to be recovered of the whole vehicle calculated according to the formula in the step one, and a torque difference value between the torque value needing to be recovered of the whole vehicle actually transmitted to the VCU by the IBC and the torque value needing to be recovered of the whole vehicle calculated according to the formula in the step one is converted into hydraulic brake pressure to act on rear wheels of the vehicle, so that the vehicle is ensured to be in a stable state;

in the third case: and when the whole vehicle is in a stable state, but the maximum recoverable torque is gradually reduced and is smaller than the torque value which is calculated according to the formula in the step one and needs to be recovered, the torque value which is transmitted to the VCU by the IBC and needs to be recovered by the whole vehicle is the maximum recoverable torque value, and the torque difference value between the torque value which is actually transmitted to the VCU by the IBC and the torque value which needs to be recovered by the whole vehicle and is calculated according to the formula in the step one is converted into hydraulic braking pressure to act on the front wheels or the rear wheels of the vehicle.

2. The coordinated control method for recovering sliding energy and braking energy of the electric vehicle as claimed in claim 1, wherein the maximum recoverable torque VCU is calculated according to the capacities of the battery and the motor, and the result is transmitted to the IBC.

3. The coordinated control method for the coasting energy recovery and the braking energy recovery of the electric vehicle as claimed in claim 1, wherein said coasting energy recovery torque value and said maximum torque value recoverable by the motor are calculated by the VCU and transmitted to the IBC.

4. The method for coordinately controlling coasting energy recovery and braking energy recovery of an electric vehicle as claimed in claim 1, wherein said braking energy recovery torque value is calculated by IBC as follows:

the first step is as follows: converting the pedal travel into braking deceleration after looking up a table;

the second step is that: braking deceleration speed, vehicle mass, tire rolling radius/reduction ratio, and braking energy recovery torque value.

5. The coordinated control method for recovering sliding energy and braking energy of the electric vehicle as claimed in claim 1, wherein the hydraulic braking pressure is torque difference/(cp x 2 r), wherein cp is braking force coefficient and has a unit of N/bar, and r is effective radius of the brake.

Technical Field

The invention belongs to the technical field of vehicle energy recovery, and particularly relates to a coordinated control method for braking energy recovery and sliding energy recovery of an electric vehicle.

Background

The endurance mileage is an important index for evaluating the performance of the electric vehicle, and when the electric vehicle is in a sliding working condition and a braking working condition, the sliding energy recovery and the braking energy recovery can be carried out so as to increase the endurance mileage of the whole vehicle.

The existing sliding energy recovery is controlled by a VCU (virtual vehicle control unit), the starting is judged based on the accelerating and decelerating intention of a driver, and the control is mainly carried out by using an accelerator signal, the charge state of a battery and the power torque characteristic of a motor; the braking energy recovery is controlled by the IBC, the judgment based on the braking intention is started, a brake pedal switch or a travel signal, a braking pressure signal and a motor recoverable energy signal are mainly used, the IBC coordinates and controls the motor braking and the hydraulic braking according to the motor recoverable energy and the stability factor in the braking process, and the wheel end braking torque is ensured to be consistent with the requirement of a driver. This solution presents two problems: 1) the VCU sliding torque value can influence the function control of the IBC, meanwhile, the function of the IBC can influence the control of the VCU sliding torque, two controllers are needed to coordinate control, and if the superposition and handover control of two types of braking are not smooth, the problems of vehicle deceleration fluctuation and the accuracy of each function control of the IBC are easy to occur; 2) the energy recovery torque is concentrated on the driving shaft, so that driving shaft instability is easily caused, vehicle instability energy recovery exits, and the energy recovery rate is low.

Therefore, the need to design a control method for coordinately controlling coasting energy recovery and braking energy recovery is a problem to be solved in the art.

Disclosure of Invention

In order to overcome the problems, the invention provides a coordination control method for the sliding energy recovery and the braking energy recovery of an electric vehicle, which relates to a VCU (vehicle control unit) and an IBC (integrated brake control unit), and aims to improve the control precision, the deceleration consistency and the energy recovery rate of the whole vehicle.

In order to achieve the purpose, the invention adopts the technical scheme that:

a method for coordinately controlling sliding energy recovery and braking energy recovery of an electric vehicle comprises the following steps:

the following three cases are distinguished:

in the first case: the IBC calculates the torque value of the whole vehicle needing to be recovered according to the following formula:

the torque value required to be recovered by the whole vehicle is the sliding energy recovery torque value plus the braking energy recovery torque value;

in the second case: the whole vehicle has instability tendency, but the maximum recoverable torque is enough

When the whole vehicle has instability tendency, wheels have locking tendency and are divided into two working conditions: the driver steps on the brake and the driver does not step on the brake; when a driver does not tread on the brake, the IBC performs PID control according to the slip rate of the front wheels of the vehicle, namely the torque value needing to be recovered by the whole vehicle transmitted to the VCU by the IBC is lower than the sliding energy recovery torque value, and the larger the slip rate of the front wheels of the vehicle is, the lower the torque value needing to be recovered by the whole vehicle transmitted to the VCU by the IBC is, so as to ensure that the vehicle is in a stable state;

when a driver steps on the brake, the IBC performs PID control according to the four-wheel slip rate, namely the torque value needing to be recovered of the whole vehicle transmitted to the VCU by the IBC is lower than the torque value needing to be recovered of the whole vehicle calculated according to the formula in the step one, and a torque difference value between the torque value needing to be recovered of the whole vehicle actually transmitted to the VCU by the IBC and the torque value needing to be recovered of the whole vehicle calculated according to the formula in the step one is converted into hydraulic brake pressure to act on rear wheels of the vehicle, so that the vehicle is ensured to be in a stable state;

in the third case: and when the whole vehicle is in a stable state, but the maximum recoverable torque is gradually reduced and is smaller than the torque value which is calculated according to the formula in the step one and needs to be recovered, the torque value which is transmitted to the VCU by the IBC and needs to be recovered by the whole vehicle is the maximum recoverable torque value, and the torque difference value between the torque value which is actually transmitted to the VCU by the IBC and the torque value which needs to be recovered by the whole vehicle and is calculated according to the formula in the step one is converted into hydraulic braking pressure to act on the front wheels or the rear wheels of the vehicle.

The maximum recoverable torque is calculated by the VCU from the capabilities of the motor and battery and the result is transmitted to the IBC.

The coasting energy recovery torque value and the motor recoverable maximum torque value are calculated by the VCU and transmitted to the IBC.

The braking energy recovery torque value is calculated by IBC, and the calculation process is as follows:

the first step is as follows: converting the pedal travel into braking deceleration after looking up a table;

the second step is that: braking deceleration speed, vehicle mass, tire rolling radius/reduction ratio, and braking energy recovery torque value.

The hydraulic brake pressure is the torque difference/(cp x 2 r), where cp is the braking force coefficient in N/bar and r is the brake effective radius.

The invention has the beneficial effects that:

the IBC is used as a controller for energy recovery, the sliding energy recovery is still calculated by the VCU, the algorithm of each controller is relatively mature, the problem is controlled by the system, and meanwhile, the IBC function control precision, the consistency of the deceleration of the whole vehicle and the energy recovery rate can be improved.

Detailed Description

The present invention will be described in further detail with reference to examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention.

In the description of the present invention, unless expressly stated or limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, e.g., as meaning permanently connected, removably connected, or integral to one another; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

In the description of the present embodiment, the terms "upper", "lower", "left", "right", and the like are used for convenience of description and simplicity of operation, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used only for descriptive purposes and are not intended to have any special meaning.

Example 1

A method for coordinately controlling sliding energy recovery and braking energy recovery of an electric vehicle comprises the following steps:

the IBC judges whether the whole vehicle is in a stable state or not according to signals of the sensors, can actively boost pressure to control hydraulic braking torque, can control hydraulic braking force distribution of front and rear wheels according to the hydraulic braking torque, and can actively boost pressure without being fed back to feet of a driver; combining these advantages of the IBC, energy recovery as a deceleration action can be considered as braking, and the control of braking is uniformly coordinated by the IBC.

The IBC carries out logic processing according to the stable state of the whole vehicle, the recoverable maximum torque value of the motor, the sliding energy recovery torque value and the braking energy recovery torque value, calculates the torque value required to be recovered by the whole vehicle, sends the torque value to the VCU, and controls the motor to complete energy recovery by the VCU.

The following three cases are distinguished:

in the first case: the IBC calculates the torque value of the whole vehicle needing to be recovered according to the following formula:

the torque value required to be recovered by the whole vehicle is the sliding energy recovery torque value plus the braking energy recovery torque value;

in the second case: the whole vehicle has instability tendency, but the maximum recoverable torque is enough

When the whole vehicle has instability tendency, wheels have locking tendency and are divided into two working conditions: the driver steps on the brake and the driver does not step on the brake; when a driver does not step on the brake, the IBC performs PID control according to the slip rate of the front wheels of the vehicle, and adjusts the torque value of the whole vehicle needing to be recovered in real time, namely the torque value of the whole vehicle needing to be recovered and transmitted to the VCU by the IBC is lower than the sliding energy recovery torque value, and the larger the slip rate of the front wheels of the vehicle is, the lower the torque value of the whole vehicle needing to be recovered and transmitted to the VCU by the IBC is, so as to ensure that the vehicle is in a stable state;

when a driver steps on the brake, the IBC performs PID control according to the four-wheel slip rate, namely the torque value required to be recovered of the whole vehicle transmitted to the VCU by the IBC is lower than the torque value required to be recovered of the whole vehicle calculated according to the formula in the step one, and a torque difference value between the torque value required to be recovered of the whole vehicle actually transmitted to the VCU by the IBC and the torque value required to be recovered of the whole vehicle calculated according to the formula in the step one is converted into hydraulic brake pressure to act on rear wheels of the vehicle, so that the hydraulic brake and the recovery torque of the whole vehicle are adjusted in real time, and the vehicle is ensured to be in a stable state; meanwhile, the actual deceleration of the whole vehicle is ensured to be close to the target deceleration or close to the maximum deceleration which can be provided by the road surface;

in the third case: the whole vehicle is in a stable state, but the maximum recoverable torque of the whole vehicle is gradually reduced (when the speed of the whole vehicle is reduced or the SOC value is changed, the maximum recoverable torque of the whole vehicle is reduced), and when the maximum recoverable torque of the whole vehicle is smaller than the torque value which is calculated according to the formula in the step one and needs to be recovered, the torque value which is transmitted to the VCU by the IBC and needs to be recovered by the whole vehicle is the maximum recoverable torque value, and the torque difference value between the torque value which is actually transmitted to the VCU by the IBC and the torque value which needs to be recovered by the whole vehicle and is calculated according to the formula in the step one is converted into hydraulic braking pressure to act on front wheels or rear wheels of the vehicle.

The maximum recoverable torque is calculated by the VCU from the capabilities of the motor and battery and the result is transmitted to the IBC.

The coasting energy recovery torque value and the motor recoverable maximum torque value are calculated by the VCU and transmitted to the IBC.

The braking energy recovery torque value is calculated by IBC, and the calculation process is as follows:

the first step is as follows: converting the pedal stroke into braking deceleration after looking up a table (stroke-deceleration);

the second step is that: braking deceleration speed, vehicle mass, tire rolling radius/reduction ratio, and braking energy recovery torque value.

The hydraulic brake pressure is the torque difference/(cp x 2 r), where cp is the braking force coefficient in N/bar and r is the effective radius of the brake.

For a front-driving vehicle, energy recovery acts on a driving shaft, when energy recovery exits (the maximum recoverable torque value is reduced or the front shaft is unstable), the IBC coordinates the energy recovery of the front shaft and hydraulic braking of the front shaft and the rear shaft, controls the energy recovery to exit, correspondingly increases the braking hydraulic pressure, ensures the deceleration of the whole vehicle to be unchanged and the stability of the vehicle, and simultaneously recovers the energy to the maximum extent.

According to the technical scheme, the IBC is used as the controller for energy recovery, sliding energy recovery and braking energy recovery are coordinated, hydraulic braking and energy recovery can be coordinated, braking force distribution of a driving shaft and a non-driving shaft can be coordinated, and the deceleration of the whole vehicle is ensured, so that the IBC function control accuracy, the deceleration consistency of the whole vehicle and the energy recovery rate are improved.

Although the preferred embodiments of the present invention have been described in detail, the scope of the present invention is not limited to the details of the foregoing embodiments, and any simple modifications within the technical scope of the present invention and the technical solutions and inventive concepts thereof disclosed by the present invention may be equally replaced or changed by those skilled in the art within the technical scope of the present invention.

It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.