CN109398101B - Composite braking transition process control method - Google Patents
Composite braking transition process control method Download PDFInfo
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- CN109398101B CN109398101B CN201811044430.8A CN201811044430A CN109398101B CN 109398101 B CN109398101 B CN 109398101B CN 201811044430 A CN201811044430 A CN 201811044430A CN 109398101 B CN109398101 B CN 109398101B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L7/00—Electrodynamic brake systems for vehicles in general
- B60L7/24—Electrodynamic brake systems for vehicles in general with additional mechanical or electromagnetic braking
- B60L7/26—Controlling the braking effect
Abstract
The invention relates to a composite brake transition process control method, which aims at the problem that the response speeds of a motor brake subsystem and a hydraulic brake subsystem in a vehicle composite brake system are different, the motor brake force directly compensates the deviation between the hydraulic brake force demand and the actual hydraulic brake force, and in addition, a motor force correction module is added, so that a motor has compensation capacity under each transition working condition. Compared with the prior art, the invention improves the braking consistency of the motor under the hydraulic pressure intervention working condition and can effectively reduce the impact degree of the composite braking transition process.
Description
Technical Field
The invention relates to the technical field of automobile composite braking, in particular to a composite braking transition process control method.
Background
The hybrid braking system generally comprises a motor braking subsystem and a hydraulic braking subsystem, and the braking demand of the electric automobile is responded by the regenerative braking of the driving motor and the hydraulic braking system together. An Electro-hydraulic Brake System (EHB) is a novel Brake-by-wire System with an active boosting function, is a development trend of an automobile hydraulic Brake System, and has the outstanding advantages of accurate control of hydraulic braking force, easiness in realization of regenerative braking and the like.
When the vehicle brakes, the braking force distribution strategy preferentially adopts the motor braking force under the condition of ensuring the braking safety, and when the motor braking force can not meet the braking requirement, the hydraulic braking force is applied. However, since the electric machine is limited by the regenerative braking torque that can be generated at a high speed, and the regenerative braking torque cannot be provided at a low speed, the following typical transient conditions occur in the hybrid braking:
1) when the target braking strength is changed from low-strength braking to medium-strength braking, the electronic hydraulic system intervenes in the braking after the motor reaches the peak torque;
2) the electronic hydraulic brake system withdraws from braking before the motor independently responds to the braking requirement along with the change of the target braking strength from the medium strength to the low strength braking;
3) when the braking demand is kept unchanged, the rotating speed of the motor is reduced to the critical rotating speed along with the continuous reduction of the vehicle speed, the generating efficiency of the motor is low, the heat is serious, the regenerative braking force is withdrawn from the braking for protecting the motor, and at the moment, the hydraulic braking force is increased sharply because the total braking demand is unchanged.
Because the response speeds of the motor and the hydraulic braking system are different, the response speed of the motor is high, and the response speed of the hydraulic system is lower than that of the motor, the composite braking can generate larger braking impact degree (namely, derivative of braking deceleration) under a transition working condition, and the smoothness and comfort of the braking are deteriorated. At present, research in the field of composite braking mainly provides a control strategy of regenerative braking, and braking force of front and rear axles is reasonably distributed. The state of the impact degree in the whole braking process is not paid much attention, so that the actual effect of a plurality of braking energy recovery strategies cannot be reflected. Therefore, it is necessary to provide a control method capable of effectively reducing the impact degree during the composite braking transition.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a composite braking transition process control method for reducing the impact degree of the composite braking transition process.
The purpose of the invention can be realized by the following technical scheme:
a compound brake transient process control method, the method comprising the steps of:
(1) according to the controlled vehicle model and the composite braking system, acquiring vehicle parameters and motor parameters, and determining the braking deceleration corresponding to the upper limit value of the motor braking force;
(2) a motor force correction module is constructed according to the braking intention and the braking deceleration corresponding to the upper limit value of the motor braking force, and the upper limit value of the motor braking force is adjusted according to the motor force correction module;
preferably, the specific step of adjusting the upper limit value of the motor braking force by the motor force correction module includes:
a) judging the target braking deceleration according to the braking demand, if the target braking deceleration needs to be increased, carrying out the next step, otherwise, keeping the upper limit value of the motor braking force unchanged;
b) judging the target braking deceleration, if the target braking deceleration is smaller than a set threshold, reducing the upper limit value of the motor braking force, otherwise, executing the next step;
c) and judging whether the target braking deceleration is in the set space, if so, recovering the upper limit value of the motor braking force, and otherwise, keeping the upper limit value of the current motor braking force unchanged.
Preferably, the motor force correction module is controlled by a logic threshold value.
Preferably, the threshold is 0.1 g.
Preferably, the setting space is 0.1g to 0.15 g. g is the acceleration of gravity, equal to about 9.8 m/s.
(3) Distributing the braking force according to the adjusted upper limit value of the motor braking force to obtain a target motor braking force and a target hydraulic braking force;
(4) and solving the difference between the hydraulic braking force demand and the actual hydraulic braking force to be used as a part of the motor demand torque, namely, solving the difference between the target hydraulic braking force and the actual hydraulic braking force to be used as the motor braking compensation force. Superposing the obtained motor braking compensation force and the target motor force to jointly act on the motor braking subsystem, and obtaining the output motor braking force of the motor braking subsystem; meanwhile, the target hydraulic pressure is applied to the hydraulic braking subsystem, and the output hydraulic braking force of the hydraulic braking subsystem is obtained.
(5) And controlling the composite braking transition process of the vehicle according to the output motor braking force of the motor braking subsystem and the output hydraulic braking force of the hydraulic braking subsystem.
Compared with the prior art, the invention has the following advantages:
the method aims at the problem that the response speeds of a motor braking subsystem and a hydraulic braking subsystem in an automobile composite braking system are different, aims to directly compensate the deviation between the hydraulic braking force demand and the actual hydraulic braking force by the motor braking force, enables the motor to have compensation capacity under each transition working condition by adding a motor force correction module, improves the braking consistency of the motor under the hydraulic pressure intervention working condition, and enables the total braking force to be closer to the total required braking force under the transition working condition, thereby improving the braking impact caused by the slow response speed and the overshoot of the hydraulic system;
in the method, the difference between the hydraulic braking force demand and the actual hydraulic braking force is solved and then is used as a part of the torque required by the motor, so that closed-loop feedback of the hydraulic braking force is formed, and a better control effect can be realized in the composite braking transition process.
Drawings
FIG. 1 is a schematic flow chart of a hybrid braking transient control method according to the present invention;
FIG. 2 is a logic diagram of motor force correction in an embodiment of the present invention;
FIG. 3 is a graph of bench test results without a control strategy in an embodiment of the present invention;
FIG. 4 is a graph showing the results of a bench test using the control method of the present invention in an embodiment of the present invention.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.
Examples
The invention relates to a control method for a composite braking transition process, which comprises the following steps:
step one, analyzing the whole vehicle parameters and the motor parameters based on the researched vehicle model and the composite braking system, and determining that the braking deceleration corresponding to the upper limit value of the motor force is 0.1 g.
Step two, determining a logic algorithm of the motor force correction module based on the vehicle information and the data obtained in the step one:
the motor force correction logic is shown in fig. 2, according to the vehicle state, if the braking demand is increasing and the braking deceleration is less than 0.1g, the hydraulic braking force is about to intervene, the upper limit value of the motor force of the braking force distribution is lower than the maximum value, so that the insufficient braking force generated due to hysteresis when the hydraulic braking force intervenes can be coordinately compensated by the motor; when the braking demand is still increased and the braking deceleration is 0.1g-0.15g, the transition process gradually enters into a tail sound, so that the upper limit value of the motor braking force distributed by the braking force is gradually recovered to the maximum value to recover more energy; if the braking demand is maintained at a certain value, the braking force is distributed so that the upper limit value of the motor braking force is always the maximum value.
Distributing the braking force according to the adjusted upper limit value of the motor braking force to obtain a target motor braking force and a target hydraulic braking force; the difference between the hydraulic braking force demand and the actual hydraulic braking force is used as a part of the motor demand torque, and the difference is superposed with the target motor force and is applied to the motor braking subsystem together to obtain the output motor braking force of the motor braking subsystem; meanwhile, the target hydraulic pressure is applied to the hydraulic braking subsystem, and the output hydraulic braking force of the hydraulic braking subsystem is obtained, as shown in fig. 1.
And step four, controlling the composite braking transition process of the vehicle according to the output motor braking force of the motor braking subsystem and the output hydraulic braking force of the hydraulic braking subsystem.
The composite braking transition process evaluation index is expressed by the derivative of the braking impact degree, namely, the deceleration. The method provided by the invention is verified according to the actual bench test working condition data. The bench test working conditions are as follows: the initial vehicle speed was 40km/h, the road adhesion coefficient was 0.8, and the vehicle braking strength was gradually increased from 0 to 0.4g and remained unchanged until the vehicle speed was reduced to 0. The results of the bench test are shown in fig. 3 and 4. Through a bench test, compared with a non-control strategy (the non-control strategy is that the target hydraulic pressure and the target motor force in the figure 1 are directly supplied to a hydraulic braking system and a braking motor respectively), the vehicle impact degree under the working condition of hydraulic pressure intervention after the control method is adopted is 28.26m/s3Reduced to 18.39m/s335.0% reduction (hydraulic pressure withdrawal condition is similar to hydraulic pressure intervention condition and is not discussed); the vehicle impact degree under the regenerative braking low-speed withdrawal working condition is 60.94m/s3Reduced to 16.84m/s3The reduction is 72.4%. Therefore, the control method can greatly reduce the impact degree in the composite braking transition process.
While the invention has been described with reference to specific embodiments, the invention is not limited thereto, and those skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope of the invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (4)
1. A composite brake transient process control method, characterized in that the method comprises the steps of:
s1: according to the controlled vehicle model and the composite braking system, acquiring vehicle parameters and motor parameters, and determining the braking deceleration corresponding to the upper limit value of the motor braking force;
s2: a motor force correction module is constructed according to the braking intention and the braking deceleration corresponding to the upper limit value of the motor braking force, and the upper limit value of the motor braking force is adjusted according to the motor force correction module;
s3: distributing the braking force according to the adjusted upper limit value of the motor braking force to obtain a target motor braking force and a target hydraulic braking force;
s4: the difference between the hydraulic braking force demand and the actual hydraulic braking force is used as a motor braking compensation force, and the motor braking compensation force and the target motor force are superposed and jointly applied to the motor braking subsystem to obtain the output motor braking force of the motor braking subsystem; simultaneously applying the target brake fluid pressure to the hydraulic brake subsystem to obtain the output hydraulic brake force of the hydraulic brake subsystem;
s5: controlling the composite braking transition process of the vehicle according to the output motor braking force of the motor braking subsystem and the output hydraulic braking force of the hydraulic braking subsystem;
the specific steps of adjusting the upper limit value of the motor braking force by the motor force correction module comprise:
1) judging the target braking deceleration according to the braking demand, if the target braking deceleration needs to be increased, carrying out the next step, otherwise, keeping the upper limit value of the motor braking force unchanged;
2) judging the target braking deceleration, if the target braking deceleration is smaller than a set threshold, reducing the upper limit value of the motor braking force, otherwise, executing the next step;
3) and judging whether the target braking deceleration is in the set space, if so, recovering the upper limit value of the motor braking force, and otherwise, keeping the upper limit value of the current motor braking force unchanged.
2. The composite brake transient process control method of claim 1, wherein said motor force modification module is a logic threshold control.
3. The compound brake transient control method of claim 1, wherein said threshold is 0.1 g.
4. The composite brake transient process control method according to claim 1, wherein the set space is 0.1g to 0.15 g.
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| CN201811044430.8A CN109398101B (en) | 2018-09-07 | 2018-09-07 | Composite braking transition process control method |
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| CN113815424B (en) * | 2020-06-19 | 2023-09-22 | 广州汽车集团股份有限公司 | Vehicle braking force control method, device and computer readable storage medium |
| CN112061094A (en) * | 2020-07-31 | 2020-12-11 | 盐城工学院 | New energy automobile hydraulic braking system |
| CN112109705A (en) * | 2020-09-23 | 2020-12-22 | 同济大学 | Collision avoidance optimization control system and method for extended-range distributed driving electric vehicle |
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| DE19834222B4 (en) * | 1997-07-30 | 2009-04-09 | Aisin Seiki K.K., Kariya | Brake control system for an electrically operated vehicle |
| CN101913352A (en) * | 2010-08-02 | 2010-12-15 | 清华大学 | Coordinated braking control method of electric automobile |
| EP2275314A1 (en) * | 2009-07-16 | 2011-01-19 | Aisin Aw Co., Ltd. | Guidance device, guidance method, and guidance program |
| US8151919B2 (en) * | 2010-01-04 | 2012-04-10 | Chen Tien-Li | Vehicle-used composite braking/accelerating system |
| CN105523028A (en) * | 2015-12-17 | 2016-04-27 | 扬州泰博汽车电子智能科技有限公司 | Electronic-hydraulic compound brake system with electric brake assist function |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101734163B (en) * | 2010-01-18 | 2013-04-10 | 吉林大学 | Electromechanical combined regenerative braking control system for electric vehicle and control strategy thereof |
| CN103991384B (en) * | 2014-05-26 | 2016-04-20 | 北京理工大学 | A kind of composite braking system of elec. vehicle and composite brakig method thereof |
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Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1132404A (en) * | 1997-06-24 | 1999-02-02 | Nabco Ltd | Travel motion control equipment for electric vehicle |
| DE19834222B4 (en) * | 1997-07-30 | 2009-04-09 | Aisin Seiki K.K., Kariya | Brake control system for an electrically operated vehicle |
| EP2275314A1 (en) * | 2009-07-16 | 2011-01-19 | Aisin Aw Co., Ltd. | Guidance device, guidance method, and guidance program |
| US8151919B2 (en) * | 2010-01-04 | 2012-04-10 | Chen Tien-Li | Vehicle-used composite braking/accelerating system |
| CN101913352A (en) * | 2010-08-02 | 2010-12-15 | 清华大学 | Coordinated braking control method of electric automobile |
| CN105523028A (en) * | 2015-12-17 | 2016-04-27 | 扬州泰博汽车电子智能科技有限公司 | Electronic-hydraulic compound brake system with electric brake assist function |
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