阅读说明：本技术 一种非ebs平台新能源商用车复合制动策略 (Compound braking strategy for non-EBS platform new-energy commercial vehicle ) 是由 冯燕 田伟 顾红星 白志刚 于 2021-01-08 设计创作，主要内容包括：本发明公开了一种非EBS平台新能源商用车复合制动策略,其基于制动系统实现,制动系统包括制动踏板、VCU(整车控制器)、电机、MCU(电机控制器)、气制动系统、ABS防抱死系统,本发明提供的电制动控制策略,综合考虑汽车处于轮速不匹配的工况下,也就是ABS系统工作状态下的控制方法：综合来说,既保留了电机制动能量回馈,提高车辆能源利用率,减少了车辆行车制动的使用,降低车辆制动器的磨损及热损耗；又考虑了防抱死系统的激活,合理减小车辆的电制动力,提高了整车制动的稳定性和安全性。(The invention discloses a non-EBS platform new energy commercial vehicle composite braking strategy, which is realized based on a braking system, wherein the braking system comprises a brake pedal, a VCU (vehicle control unit), a motor, an MCU (motor controller), a pneumatic braking system and an ABS (anti-lock braking system). The electric braking control strategy provided by the invention comprehensively considers the control method of the vehicle under the working condition that the wheel speed is not matched, namely the working state of the ABS system: in a comprehensive way, the motor braking energy feedback is reserved, the vehicle energy utilization rate is improved, the use of vehicle service braking is reduced, and the abrasion and heat loss of a vehicle brake are reduced; and the activation of an anti-lock system is considered, the electric braking force of the vehicle is reasonably reduced, and the stability and the safety of the braking of the whole vehicle are improved.)

1. The utility model provides a compound braking strategy of new energy commercial car of non-EBS platform which characterized in that: the method comprises the following steps:

the method comprises the following steps: firstly, a VCU acquires that the travel of a brake pedal is not 0, the whole vehicle enters braking at the moment, the VCU calculates the magnitude of the current mechanism power torque according to the current motor state, the travel of the brake pedal and the energy allowed to be recovered by a battery system, and records the magnitude as a calculation result T (t), wherein T (t) is a calculation value under the current condition and is not a fixed value;

step two: if the ABS is not activated, namely the message information is always 00, the VCU directly sends the calculated negative torque result request to the MCU, and the MCU controls the motor to make a corresponding response;

step three: if the ABS is activated, namely the message information is changed from 00 to 01, and the ABS activation times n are recorded as 1, the VCU judges whether the whole vehicle is in a light braking state or a heavy braking state according to the stroke of the brake pedal;

step four: if the travel of the brake pedal returns to 0, the whole vehicle does not need to be braked at the moment, the motor torque calculated by the VCU is in positive correlation with the brake pedal, the travel of the brake pedal is 0, the requested motor negative torque is automatically 0, the ABS activation times n are cleared at the moment, and the braking state is finished;

step five: if the brake pedal is still in a braking state, the VCU judges whether the ABS is activated again so as to determine whether the requested negative torque of the motor needs to be weakened again, if the ABS is activated again, the ABS activation frequency n is changed into 2, and the depth of the brake pedal is judged again;

step six: if the travel of the brake pedal returns to 0, the whole vehicle does not need to be braked at the moment, the requested negative torque of the motor is automatically 0, the number n of times of activation of the ABS is cleared at the moment, the braking state at the moment is finished, if the brake pedal is still in the braking state, the number n of times of activation of the ABS is assumed to reach A times, the VCU sets the request of the negative torque of the motor to 0 at the moment, the number n of times of activation of the ABS is cleared, and the electric braking state is finished.

2. The non-EBS platform new energy commercial vehicle compound braking strategy of claim 1, wherein: in the first step:

(1.1) obtaining a torque value T1 at the current rotating speed by looking up a table;

(1.2) obtaining the maximum allowable recovery power of the current battery system according to the T-P-9550/n, and calculating to obtain T2;

(1.3) according to the maximum allowable torque T3 of the current motor, the three are taken small, and T (T) is the pedal opening degree min { T1, T2, T3}

3. The non-EBS platform new energy commercial vehicle compound braking strategy of claim 2, wherein:

in the third step:

(3.1) if the stroke of the brake pedal exceeds a certain threshold value, the vehicle is in a heavy braking state, the pneumatic braking of the whole vehicle is already involved in working, at the moment, the VCU sets the motor braking force request to 0, so that the whole vehicle is completely in the pneumatic braking state, and the motor does not participate in the braking;

(3.2) if the brake pedal is below the threshold at this time, the VCU changes the motor braking force negative torque request to be in the calculationThe result T (t) is multiplied by a ratio x₁(0 < x1 < 1), and entering the next judgment process.

4. The non-EBS platform new energy commercial vehicle compound braking strategy of claim 2, wherein:

in the fifth step:

(5.1) if the electric vehicle is in a heavy treading state, setting the motor braking force request to be 0 by the VCU, clearing the ABS activation times n, and ending the electric braking state;

(5.2) if the light step condition, the VCU will request the negative torque of the motor at x₁T (t) is multiplied again by a ratio x₂Is changed into x₁·x₂And T (t), entering the next judgment process.

The technical field is as follows:

the invention relates to a composite braking strategy for a non-EBS platform new-energy commercial vehicle, and belongs to the technical field of new-energy vehicles.

Background art:

the new energy automobile saves fuel energy, has low noise, high thermal efficiency and less pollutant emission, becomes the development trend of the future automobile and is increasingly paid attention. The braking system of the new energy automobile comprises a mechanical braking part and a regenerative braking part, and the regenerative braking function is one of the biggest differences between the new energy electric automobile and the traditional internal combustion engine automobile. The mechanical brake of the commercial vehicle with new energy generally adopts a traditional pneumatic brake system, the brake energy is completely converted into heat in the braking process and is lost, and the mechanical parts are abraded greatly, so that the brake performance is poor, and the commercial vehicle needs to be overhauled and maintained frequently. The electric power regenerative braking system is provided with the vehicle-mounted energy storage device, and the electric energy converted from braking kinetic energy is stored in the vehicle-mounted energy storage device, so that the energy utilization rate is improved, and the continuation of the journey mileage of the new energy automobile is favorably improved. How to reasonably and effectively combine mechanical braking and electric regenerative braking, the abrasion of braking mechanical parts is reduced and the braking energy can be effectively recovered while the stability and the safety of the braking of the new energy commercial vehicle are improved, and the method has important theoretical value and practical economic benefit.

The brake system used by the new-energy commercial vehicle is not popularized with an EBS system, and a brake force distribution strategy aiming at the non-EBS platform new-energy commercial vehicle is the key for ensuring the safety, the energy conservation and the comfort of the vehicle brake.

The control schematic diagram of the currently-used braking system is shown in fig. 1, and the braking scheme divides the stroke of the brake pedal into an electric braking stroke and an air braking stroke, wherein the electric braking can be triggered in the whole course, and the air braking is triggered only after the brake pedal is larger than a certain opening degree. The scheme has the disadvantages that when only motor feedback braking exists, if wheels slip under certain road conditions to trigger the ABS function, the suppression logic of the auxiliary braking operation when the ABS operates can cause the vehicle to immediately cancel the feedback braking of the motor, meanwhile, air braking is not involved, a driver can feel that the vehicle loses the braking force instantly, and the driver can adjust the depth of a brake pedal to cause the air braking to be involved, but the linear degree of braking and the driving feeling are not well experienced.

Therefore, there is a need to improve the prior art to overcome the deficiencies of the prior art.

The invention content is as follows:

the invention provides a composite braking strategy for a non-EBS platform new-energy commercial vehicle, which aims to solve the problems in the prior art, can solve the problem of brake force distribution of the new-energy commercial vehicle under the non-EBS platform, solves the problem of nonlinear influence on vehicle braking caused by sudden brake force withdrawal when an ABS is triggered in the electric braking process, can remarkably improve the brake operation experience of a driver, and greatly improves the brake stability and safety of the new-energy passenger vehicle in the electric power recovery braking process.

The technical scheme adopted by the invention is as follows: a composite braking strategy for a non-EBS platform new energy commercial vehicle comprises the following steps:

the method comprises the following steps: firstly, a VCU acquires that the travel of a brake pedal is not 0, the whole vehicle enters braking at the moment, the VCU calculates the magnitude of the current mechanism power torque according to the current motor state, the travel of the brake pedal and the energy allowed to be recovered by a battery system, and records the magnitude as a calculation result T (t), wherein T (t) is a calculation value under the current condition and is not a fixed value;

step two: if the ABS is not activated, namely the message information is always 00, the VCU directly sends the calculated negative torque result request to the MCU, and the MCU controls the motor to make a corresponding response;

step three: if the ABS is activated, namely the message information is changed from 00 to 01, and the ABS activation times n are recorded as 1, the VCU judges whether the whole vehicle is in a light braking state or a heavy braking state according to the stroke of the brake pedal;

step four: if the travel of the brake pedal returns to 0, the whole vehicle does not need to be braked at the moment, the motor torque calculated by the VCU is in positive correlation with the brake pedal, the travel of the brake pedal is 0, the requested motor negative torque is automatically 0, the ABS activation times n are cleared at the moment, and the braking state is finished;

step five: if the brake pedal is still in a braking state, the VCU judges whether the ABS is activated again so as to determine whether the requested negative torque of the motor needs to be weakened again, if the ABS is activated again, the ABS activation frequency n is changed into 2, and the depth of the brake pedal is judged again;

step six: if the travel of the brake pedal returns to 0, the whole vehicle does not need to be braked at the moment, the requested negative torque of the motor is automatically 0, the number n of times of activation of the ABS is cleared at the moment, the braking state at the moment is finished, if the brake pedal is still in the braking state, the number n of times of activation of the ABS is assumed to reach A times, the VCU sets the request of the negative torque of the motor to 0 at the moment, the number n of times of activation of the ABS is cleared, and the electric braking state is finished.

Further, in the step one:

(1.1) obtaining a torque value T1 at the current rotating speed by looking up a table;

(1.2) obtaining the maximum allowable recovery power of the current battery system according to the T-P-9550/n, and calculating to obtain T2;

(1.3) according to the maximum allowable torque T3 of the current motor, the three are taken small, and T (T) is the pedal opening degree min { T1, T2, T3}

Further, in the third step:

(3.1) if the stroke of the brake pedal exceeds a certain threshold value, the vehicle is in a heavy braking state, the pneumatic braking of the whole vehicle is already involved in working, at the moment, the VCU sets the motor braking force request to 0, so that the whole vehicle is completely in the pneumatic braking state, and the motor does not participate in the braking;

(3.2) if the brake pedal is below the threshold at that time, the VCU modifies the motor braking force negative torque request to multiply the calculated result T (t) by a ratio x₁(0 < x1 < 1), and entering the next judgment process.

Further, in step five:

(5.1) if the electric vehicle is in a heavy treading state, setting the motor braking force request to be 0 by the VCU, clearing the ABS activation times n, and ending the electric braking state;

(5.2) if the light step condition, the VCU will request the negative torque of the motor at x₁T (t) is multiplied again by a ratio x₂Is changed into x₁·x₂And T (t), entering the next judgment process.

The invention has the following beneficial effects: the invention provides a non-EBS platform new energy commercial vehicle composite braking strategy, which comprehensively considers the control method of the vehicle under the working condition that the wheel speed is not matched, namely the working state of an ABS system: in a comprehensive way, the motor braking energy feedback is reserved, the vehicle energy utilization rate is improved, the use of vehicle service braking is reduced, and the abrasion and heat loss of a vehicle brake are reduced; and the activation of an anti-lock system is considered, the electric braking force of the vehicle is reasonably reduced, and the stability and the safety of the braking of the whole vehicle are improved.

Description of the drawings:

FIG. 1 is a schematic view of a braking system of a non-EBS platform new energy commercial vehicle.

Fig. 2 is a schematic flow chart of a composite braking strategy of a non-EBS platform new energy commercial vehicle.

Fig. 3 is a schematic flow chart of a composite braking strategy of a non-EBS platform new-energy commercial vehicle based on a certain vehicle type.

The specific implementation mode is as follows:

the invention will be further described with reference to the accompanying drawings.

Referring to fig. 1, the braking system required in the hybrid braking strategy of the non-EBS platform new energy commercial vehicle of the present invention includes a brake pedal, a VCU (vehicle control unit), a motor, an MCU (motor controller), a pneumatic braking system, and an ABS anti-lock braking system. The stroke size information of the brake pedal is collected through a hard wire by a VCU, the information such as the rotating speed, the torque and the temperature of the motor is collected through a hard wire by an MCU, the MCU is also responsible for converting the direct current energy of the battery into a three-phase alternating current power supply to drive the motor to operate, and is responsible for outputting negative torque by the motor in the electric braking process, and converting the alternating current energy recycled by the motor into the direct current energy to charge the battery. The MCU is connected with the VCU through a CAN line, the MCU transmits information such as torque, rotating speed and temperature of the motor to the VCU, the VCU transmits a current required motor torque request to the MCU, and the MCU performs further processing to control the motor to operate. When a brake pedal steps on a threshold value set by the pedal, a gas circuit is connected, the gas chamber brakes a tire, if an ABS (anti-lock brake system) detects abnormal wheel speed and a locking condition exists, the on-off of each electromagnetic valve is adjusted to control the on-off and the air pressure of the gas circuit of the gas chamber, so that a control box of the ABS for controlling the gas braking force collects the wheel speed and controls the working state of the ABS, the control box of the ABS is connected with a VCU (video command unit) through a CAN (controller area network) line, and the working state of the ABS is transmitted to the VCU through the CAN line.

Referring to fig. 2, the steps of the composite braking strategy of the non-EBS platform new energy commercial vehicle of the present invention are as follows:

the method comprises the following steps: firstly, a VCU acquires that the travel of a brake pedal is not 0, the whole vehicle enters braking at the moment, the VCU calculates the required motor braking force torque according to the current motor state, the travel of the brake pedal and the energy allowed to be recovered by a battery system and records the required motor braking force torque as a calculation result T (t), wherein T (t) is a calculation value under the current condition and is not a fixed value;

step two: if the ABS is not activated (the message information is always 00), the VCU directly sends the calculated negative torque result request to the MCU, and the MCU controls the motor to make a corresponding response;

step three: if the ABS is activated (the message information is changed from 00 to 01), and the ABS activation times n are recorded as 1, the VCU judges whether the whole vehicle is in a light braking state or a heavy braking state according to the stroke of the brake pedal;

in the third step:

(3.1) if the stroke of the brake pedal exceeds a certain threshold value, the vehicle is in a heavy braking state, the pneumatic braking of the whole vehicle is already involved in working, at the moment, the VCU sets the motor braking force request to 0, so that the whole vehicle is completely in the pneumatic braking state, and the motor does not participate in the braking;

(3.2) if the brake pedal is below the threshold at that time, the VCU modifies the motor braking force negative torque request to multiply the calculated result T (t) by a ratio x₁(x 1 is more than 0 and less than 1), and entering the next judgment process;

step four: if the travel of the brake pedal returns to 0, the whole vehicle does not need to be braked at the moment, the motor torque calculated by the VCU is in positive correlation with the brake pedal, the travel of the brake pedal is 0, the requested motor negative torque is automatically 0, the ABS activation times n are cleared at the moment, and the braking state is finished;

step five: if the brake pedal is still in a braking state, the VCU judges whether the ABS is activated again so as to determine whether the requested negative torque of the motor needs to be weakened again, and if the ABS is activated again (the message information is changed from 00 to 01 again, which needs to be explained in the following point that the message information is changed from 01 to 00 before, but the torque request is still x1T (t) without changing multiples), the ABS activation frequency n is changed to 2, and the depth of the brake pedal is judged again;

in the fifth step:

(5.1) if the electric vehicle is in a heavy treading state, setting the motor braking force request to be 0 by the VCU, clearing the ABS activation times n, and ending the electric braking state;

(5.2) if the light step condition, the VCU will request the negative torque of the motor at x₁T (t) is multiplied again by a ratio x₂(x₂The value of (d) can be calibrated according to the actual vehicle model) into x₁·x₂T (t), entering the next judging process;

step six: if the travel of the brake pedal returns to 0, the whole vehicle does not need to be braked at this time, the requested negative torque of the motor is automatically 0, the ABS activation times n are cleared at this time, the braking state is finished, if the brake pedal is still in the braking state, the VCU assumes that the ABS activation times reach A times (the value of A can be calibrated according to the actual vehicle model), the motor negative torque request is set to 0 at this time, the ABS activation times n are cleared, and the electric braking state is finished.

Referring to fig. 3, a composite braking strategy for a non-EBS platform new energy commercial vehicle based on a determined vehicle type includes the following steps:

the method comprises the following steps: firstly, a VCU acquires that the travel of a brake pedal is not 0, the whole vehicle enters braking at the moment, the VCU calculates the required motor braking force torque according to the current motor state, the travel of the brake pedal and the energy allowed to be recovered by a battery system and records the required motor braking force torque as a calculation result T (t), wherein T (t) is a calculation value under the current condition and is not a fixed value;

step two: if the ABS is not activated (the message information is always 00), the VCU directly sends the calculated negative torque result request to the MCU, and the MCU controls the motor to make a corresponding response;

step three: if the ABS is activated (the message information is changed from 00 to 01), and the ABS activation times n are recorded as 1, the VCU judges whether the whole vehicle is in a light braking state or a heavy braking state according to the stroke of the brake pedal;

in the third step:

(3.1) if the stroke of the brake pedal exceeds a certain threshold value, the vehicle is in a heavy braking state, the pneumatic braking of the whole vehicle is already involved in working, at the moment, the VCU sets the motor braking force request to 0, so that the whole vehicle is completely in the pneumatic braking state, and the motor does not participate in the braking;

and (3.2) if the brake pedal is below the threshold value at the moment, the VCU reduces the negative torque request of the motor braking force to half of the original calculation result T (t), and the next judgment flow is entered.

Step four: if the travel of the brake pedal returns to 0, the whole vehicle does not need to be braked at the moment, the motor torque calculated by the VCU is in positive correlation with the brake pedal, the travel of the brake pedal is 0, the requested motor negative torque is automatically 0, the ABS activation times n are cleared at the moment, and the braking state is finished;

step five: if the brake pedal is still in a braking state, the VCU judges whether the ABS is activated again so as to determine whether the requested negative torque of the motor is half or half again, and if the ABS is activated again (the message information is changed from 00 to 01 again, which needs to be explained in the following point that the message information is changed from 01 to 00 before, but the torque request is still 0.5T (t) without changing multiples), the ABS activation frequency n is changed to 2, and the depth of the brake pedal is judged again;

in the fifth step:

(5.1) if the electric vehicle is in a heavy treading state, setting the motor braking force request to be 0 by the VCU, clearing the ABS activation times n, and ending the electric braking state;

(5.2) if the stepping is in the light stepping state, the VCU halves the negative torque request of the motor again on 0.5T (t), changes the negative torque request into 0.25T (t), and enters the next judgment process;

step six: if the travel of the brake pedal returns to 0 next time, the whole vehicle does not need to be braked at the moment, the requested negative torque of the motor is automatically 0, the ABS activation times n are cleared at the moment, and the braking state is finished; if the brake pedal is still in a braking state, the VCU still judges whether the ABS is activated or not, so as to determine whether the requested negative torque of the motor is continuously halved or not;

step seven: if the ABS is activated again, the ABS activation times n are changed into 3, and the judgment of the depth of the brake pedal is continued;

step seven:

(7.1) if the electric vehicle is in a heavy stepping state, setting the motor braking force request to be 0 by the VCU, clearing the ABS activation times n, and ending the electric braking state;

(7.2) if the vehicle is in the light stepping state, the VCU continuously halves the negative torque request of the motor on 0.25T (t), changes the negative torque request of the motor into 0.125T (t), and enters the next judgment process.

Step eight: if the travel of the brake pedal returns to 0 next time, the whole vehicle does not need to be braked at the moment, the requested negative torque of the motor is automatically 0, the ABS activation times n are cleared at the moment, and the braking state is finished; if the brake pedal is still in a braking state, the VCU sets the negative torque request of the motor to 0 at the moment because the number of times of the previous activation of the ABS reaches 3 times, and clears the number n of the activation of the ABS to end the electric braking state.

The foregoing is only a preferred embodiment of this invention and it should be noted that modifications can be made by those skilled in the art without departing from the principle of the invention and these modifications should also be considered as the protection scope of the invention.