Regenerative braking control method for hybrid vehicle based on electronic hydraulic braking system

Abstract

The present invention discloses a hybrid vehicle regenerative braking control method based on an electronic hydraulic braking system, including: judging whether to enter a regenerative braking mode based on vehicle operating conditions, and after entering the regenerative braking working mode, the EHB distributes electro-hydraulic braking force; judging whether the motor speed signal is jittering, and if so, filtering the motor speed; calculating the actual feedback capacity of the motor based on the motor speed and the motor state; calculating the engine's back-drag torque based on the generator torque and the gear signal; calculating the actual braking torque of the motor based on the electric braking torque distributed by the EHB, the actual feedback capacity of the motor, and the engine's back-drag torque; and the EHB and the motor perform the corresponding braking torque based on the driver's braking demand and the actual braking torque of the motor. The hybrid vehicle regenerative braking control method based on the electronic hydraulic braking system of the present invention can solve the problems of mismatched braking intentions and torque control fluctuations during the regenerative braking process of hybrid vehicles.

Description

Technical Field

[0001] The present invention relates to the technical field of hybrid vehicles, and in particular to a hybrid vehicle regenerative braking control method based on an electronic hydraulic braking system. Background Art

[0002] With the increasing development of modern technology, traditional fuel vehicles consume too much energy. For the automotive industry, finding new power sources has become an important issue. The emergence of hybrid vehicles not only brings new power sources, but also reduces vehicle energy consumption by realizing regenerative braking. Its working method is to switch the motor model to power generation mode when the vehicle brakes, convert the vehicle's kinetic energy into electrical energy and store it in the battery, reducing energy consumption and increasing the vehicle's cruising range.

[0003] However, when a hybrid vehicle is performing regenerative braking, due to the presence of engine anti-lag torque and motor speed fluctuations, the vehicle deceleration does not match the driver's braking requirements and the torque control fluctuates during the regenerative braking process.

[0004] Therefore, there is an urgent need for a hybrid vehicle regenerative braking control method based on an electronic hydraulic braking system. Summary of the invention

[0005] The purpose of the present invention is to provide a hybrid vehicle regenerative braking control method based on an electronic hydraulic braking system to solve the above-mentioned problems in the prior art, and to solve the problems of braking intention mismatch and torque control fluctuation during regenerative braking of hybrid vehicles.

[0006] The present invention provides a hybrid vehicle regenerative braking control method based on an electronic hydraulic braking system, which includes:

[0007] Step S1, obtaining vehicle operating parameters, and judging whether to enter the regenerative braking mode based on the obtained vehicle operating parameters, if yes, executing step S2, otherwise executing step S10;

[0008] Step S2, entering the regenerative braking working mode, the electronic hydraulic braking system distributes the electro-hydraulic braking force;

[0009] Step S3, obtaining the motor speed signal, and determining whether the motor speed signal is jittering, if yes, executing step S4, otherwise executing step S5;

[0010] Step S4, performing filtering optimization processing on the motor speed;

[0011] Step S5, calculating the actual feedback capacity of the motor based on the motor speed and motor state after filtering;

[0012] Step S6, calculating the engine's anti-drag torque according to the generator torque and the gear position signal;

[0013] Step S7, calculating the braking torque actually required to be performed by the motor according to the electric braking torque allocated by the electronic hydraulic braking system, the actual feedback capacity of the motor, and the anti-drag torque of the engine;

[0014] Step S8, performing electro-hydraulic coordinated braking, according to the driver's braking demand and the braking torque actually required to be executed by the motor, the electronic hydraulic braking system and the motor respectively execute corresponding braking torques;

[0015] Step S9, obtaining motor state parameters, when the motor state is abnormal, executing step S10; otherwise, executing step S1;

[0016] Step S10: perform pure hydraulic braking.

[0017] As described above, the regenerative braking control method for a hybrid vehicle based on an electronic hydraulic braking system, wherein, preferably, in the step S1, the vehicle operating parameters include vehicle speed, wheel speed, SOC, engine torque, gear, brake switch, power system status, chassis system status, accelerator pedal opening, braking demand, vehicle speed validity, wheel speed validity, engine torque validity, gear validity, brake switch validity, power system status validity, chassis system status validity, accelerator pedal opening validity and braking demand validity. If all of the above signals meet the set conditions, the regenerative braking mode is entered and S2 is executed. If at least one signal does not meet the set conditions, step S10 is executed.

[0018] As described above, the hybrid vehicle regenerative braking control method based on the electronic hydraulic braking system, wherein preferably, the step S2, entering the regenerative braking working mode, the electronic hydraulic braking system performs electro-hydraulic braking force distribution, specifically includes:

[0019] The electronic hydraulic braking system distributes the electro-hydraulic braking torque according to the driver's braking demand, with electric braking priority.

[0020] In the hybrid vehicle regenerative braking control method based on the electronic hydraulic brake system as described above, preferably, the step S3 of acquiring the motor speed signal and determining whether the motor speed signal is jittering specifically includes:

[0021] A motor speed fluctuation threshold is set, and when the motor speed exceeds the motor speed fluctuation threshold, it is determined that the motor speed signal jitters.

[0022] In the hybrid vehicle regenerative braking control method based on the electronic hydraulic brake system as described above, preferably, the step S4 of filtering and optimizing the motor speed specifically includes:

[0023] Perform Kalman filtering on the motor speed.

[0024] As described above, in the hybrid vehicle regenerative braking control method based on the electronic hydraulic brake system, preferably, in the step S5, the motor state includes motor power limitation, motor phase current limitation and motor efficiency limitation.

[0025] In the hybrid vehicle regenerative braking control method based on the electronic hydraulic brake system as described above, preferably, the step S5 of calculating the actual motor feedback capacity based on the motor speed and motor state after filtering processing specifically includes:

[0026] The motor power limit value is calculated using the following formula:

[0027] (1)

[0028] in, Indicates the maximum power of the motor The motor torque allowed under the limit of Indicates the maximum power of the motor. Indicates the motor speed;

[0029] The motor phase current limit value is calculated by the following formula:

[0030] (2)

[0031] in, Indicates the maximum current allowed The motor torque allowed under the limit of represents the motor torque coefficient, Indicates the maximum current allowed;

[0032] The motor's own efficiency limit is calculated using the following formula:

[0033] (3)

[0034] in, Indicates the charging power, Indicates the motor input mechanical power, Indicates the power consumed by the internal resistance, Indicates the internal resistance value, Indicates the motor torque allowed under the limitation of the motor's own efficiency. Indicates the motor speed,

[0035] When the speed is determined, For If the power is the largest, then we have:

[0036] (4)

[0037] According to formula (4), the motor feedback capability curve is obtained.

[0038] As described above, the hybrid vehicle regenerative braking control method based on the electronic hydraulic brake system, wherein preferably, the step S9, obtaining the motor state parameter, when the motor state is abnormal, executing step S10, specifically includes:

[0039] A preset motor torque following threshold is set; when the torque following amount exceeds the preset motor torque following threshold, the regenerative braking mode is exited, pure hydraulic braking is performed, and step S10 is executed.

[0040] The present invention provides a hybrid vehicle regenerative braking control method based on an electronic hydraulic braking system. The hybrid vehicle performs regenerative braking based on the characteristics of the hybrid vehicle itself, and can achieve the compensation effect of the electric braking torque on the sudden torque. It avoids the problems of mismatch between the braking intention of the whole vehicle and the braking intention of the driver and uneven braking due to engine torque lag, gear change and speed jitter during regenerative braking of the hybrid vehicle, so that the braking of the whole vehicle is closer to the real intention of the driver, improves the smoothness and safety of the braking process, and can achieve smoother and more comfortable regenerative braking performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described below with reference to the accompanying drawings, in which:

[0042] Figure 1 A flow chart of an embodiment of a hybrid vehicle regenerative braking control method based on an electronic hydraulic braking system provided by the present invention;

[0043] Figure 2 A logic diagram of an embodiment of a hybrid vehicle regenerative braking control method based on an electronic hydraulic braking system provided by the present invention;

[0044] Figure 3 The regenerative braking distribution curve under ideal conditions;

[0045] Figure 4 This is the effect diagram of motor speed filter optimization processing;

[0046] Figure 5 This is the motor feedback capability curve;

[0047] Figure 6 is the engine anti-drag torque;

[0048] Figure 7 This is a schematic diagram of switching the regenerative braking mode when the motor status is abnormal. DETAILED DESCRIPTION

[0049] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and is in no way intended to limit the present disclosure and its application or use. The present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to make the present disclosure thorough and complete and to fully express the scope of the present disclosure to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of the components and steps, the composition of the materials, the numerical expressions and the numerical values ​​set forth in these embodiments should be interpreted as being merely exemplary and not as limiting.

[0050] The words "first", "second" and similar words used in this disclosure do not indicate any order, quantity or importance, but are only used to distinguish different parts. The words "include" or "comprises" and similar words mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of including other elements. "Up", "down" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0051] In the present disclosure, when a specific component is described as being located between a first component and a second component, there may or may not be an intermediate component between the specific component and the first component or the second component. When a specific component is described as being connected to other components, the specific component may be directly connected to the other components without an intermediate component, or may not be directly connected to the other components but have an intermediate component.

[0052] All terms (including technical terms or scientific terms) used in the present disclosure have the same meanings as those understood by ordinary technicians in the field to which the present disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries, such as general dictionaries, should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an idealized or extremely formal sense, unless explicitly defined herein.

[0053] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0054] At present, when hybrid vehicles are performing regenerative braking control, due to the presence of two power sources, the engine and the motor, there are fluctuations in the engine anti-lag torque and the motor speed, resulting in a mismatch between the vehicle deceleration and the driver's braking requirements and torque control fluctuations during the regenerative braking process, leading to poor vehicle smoothness and comfort.

[0055] EHB, or electronic hydraulic braking system, can replace the traditional vacuum booster. It can accurately sense the driver's control pedal pressure through its own sensors, and convert it into electrical signals to transmit to the control unit. The control unit controls the motor to establish corresponding braking pressure. At the same time, the electronic hydraulic braking system can also receive requests from external controllers and establish corresponding braking pressure based on the requests.

[0056] like Figure 1 and Figure 2 As shown, the hybrid vehicle regenerative braking control method based on the electronic hydraulic braking system provided in this embodiment includes the following steps in actual execution:

[0057] Step S1, obtaining vehicle operating parameters, and judging whether to enter the regenerative braking mode based on the obtained vehicle operating parameters, if yes, executing step S2, otherwise executing step S10.

[0058] In step S1, the vehicle operating parameters include vehicle speed, wheel speed, SOC, engine torque, gear, brake switch, power system state, chassis system state, accelerator pedal opening, braking demand, vehicle speed validity, wheel speed validity, engine torque validity, gear validity, brake switch validity, power system state validity, chassis system state validity, accelerator pedal opening validity and braking demand validity. If all of the above signals meet the set conditions, the regenerative braking mode is entered and S2 is executed. If at least one signal does not meet the set conditions, step S10 is executed. According to the above signals, it can be judged whether the current vehicle can enter the regenerative braking mode.

[0059] Step S2, entering the regenerative braking mode, the electronic hydraulic brake system (EHB) distributes the electro-hydraulic braking force.

[0060] Specifically, the electronic hydraulic brake system (EHB) distributes the electro-hydraulic braking torque according to the driver's braking demand and in a manner that prioritizes electric braking. After the vehicle enters the regenerative braking mode, the EHB distributes the electro-hydraulic braking force based on the principle of electric braking priority, such as Figure 3 shown.

[0061] Step S3, obtaining the motor speed signal, and determining whether the motor speed signal is jittering, if yes, executing step S4, otherwise executing step S5.

[0062] Specifically, a motor speed fluctuation threshold is set, and when the motor speed exceeds the motor speed fluctuation threshold, it is determined that the motor speed signal has jittered.

[0063] Step S4: performing filtering optimization processing on the motor speed.

[0064] Specifically, the motor speed is processed by Kalman filtering. After the electro-hydraulic braking force distribution is completed, the motor feedback capacity needs to be calculated through the motor speed and motor state. Due to the complex driving conditions of the car, the speed signal may have jitter, so Kalman filtering is used for optimization processing. Figure 4 As shown, the speed signal jitters within a certain range. After Kalman filtering, the speed signal is smoothed.

[0065] Step S5: Calculate the actual feedback capability of the motor based on the motor speed and motor state after filtering.

[0066] In step S5, the motor state includes motor power limitation, motor phase current limitation and motor efficiency limitation.

[0067] After the speed signal is filtered and optimized, the motor feedback capability curve is calculated through the motor speed, motor power limit, motor phase current limit, and motor efficiency. The calculation process is as follows:

[0068] The motor power limit is calculated using the following formula:

[0069] (1)

[0070] in, Indicates the maximum power of the motor The motor torque allowed under the limit of Indicates the maximum power of the motor. Indicates the motor speed;

[0071] The motor phase current limit is calculated by the following formula:

[0072] (2)

[0073] in, Indicates the maximum current allowed The motor torque allowed under the limit of represents the motor torque coefficient, Indicates the maximum current allowed;

[0074] The motor phase current limit refers to the influence of the IGBT of the motor driver. The motor phase current cannot exceed a certain value, otherwise there is a risk of burning out the IGBT.

[0075] Motor’s own efficiency limitation:

[0076] (3)

[0077] in, Indicates the charging power, Indicates the motor input mechanical power, Indicates the power consumed by the internal resistance, Indicates the internal resistance value, Indicates the motor torque allowed under the limitation of the motor's own efficiency. Indicates the motor speed,

[0078] At a specific speed, For If the power is the largest, then we have:

[0079] (4)

[0080] The motor feedback capability curve is obtained as follows: Figure 5 shown.

[0081] Step S6: Calculate the engine's anti-drag torque according to the generator torque and the gear position signal.

[0082] During the braking process of hybrid vehicles, there is a situation of engine torque back-drag. When the vehicle is in different gears, the magnitude of the braking torque transmitted to the wheel side is different. Therefore, the back-drag torque is calculated in real time based on the current engine torque and gear, such as Figure 6 shown.

[0083] Step S7, calculating the braking torque actually required to be performed by the motor according to the electric braking torque allocated by the electronic hydraulic braking system, the actual feedback capacity of the motor, and the anti-drag torque of the engine.

[0084] Step S8: Perform electro-hydraulic coordinated braking. According to the driver's braking demand and the braking torque actually required to be executed by the motor, the electronic hydraulic braking system and the motor respectively execute corresponding braking torques.

[0085] Step S9, obtaining motor state parameters. When the motor state is abnormal, execute step S10; otherwise, execute step S1.

[0086] Specifically, a preset motor torque following threshold is set; when the torque following amount exceeds the preset motor torque following threshold, the regenerative braking mode is exited, pure hydraulic braking is performed, and step S10 is executed.

[0087] Considering the safety during the regenerative braking process, the present invention introduces a monitoring strategy for the target electric braking torque and the actual electric braking torque. When the difference between the target electric braking torque and the actual electric braking torque exceeds a certain threshold, it is determined that the motor state is abnormal. At this time, the regenerative braking mode is exited and pure hydraulic braking is performed. Figure 6 shown.

[0088] Step S10: perform pure hydraulic braking.

[0089] The hybrid vehicle regenerative braking control method based on the electronic hydraulic braking system provided in the embodiment of the present invention performs regenerative braking on the hybrid vehicle based on the characteristics of the hybrid vehicle itself, and can realize the compensation effect of the electric braking torque on the sudden torque; avoid the problems of mismatch between the braking intention of the whole vehicle and the braking intention of the driver and uneven braking due to engine torque lag, gear changes and speed jitter during regenerative braking of the hybrid vehicle, so that the braking of the whole vehicle is closer to the actual intention of the driver, improves the smoothness and safety of the braking process, and can achieve smoother and more comfortable regenerative braking performance.

[0090] So far, various embodiments of the present disclosure have been described in detail. In order to avoid obscuring the concept of the present disclosure, some details known in the art are not described. Based on the above description, those skilled in the art can fully understand how to implement the technical solution disclosed here.

[0091] Although some specific embodiments of the present disclosure have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. It should be understood by those skilled in the art that the above embodiments may be modified or some technical features may be replaced by equivalents without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. A hybrid vehicle regenerative braking control method based on an electronic hydraulic braking system, characterized in that: include: Step S1, obtaining vehicle operating parameters, and judging whether to enter the regenerative braking mode based on the obtained vehicle operating parameters, if yes, executing step S2, otherwise executing step S10; Step S2, entering the regenerative braking working mode, the electronic hydraulic braking system distributes the electro-hydraulic braking force; Step S3, obtaining the motor speed signal, and determining whether the motor speed signal is jittering, if yes, executing step S4, otherwise executing step S5; Step S4, performing filtering optimization processing on the motor speed; Step S5, calculating the actual feedback capacity of the motor based on the motor speed and motor state after filtering, wherein the motor state includes motor power limitation, motor phase current limitation and motor efficiency limitation; Step S6, calculating the engine's anti-drag torque according to the generator torque and the gear position signal; Step S7, calculating the braking torque actually required to be performed by the motor according to the electric braking torque allocated by the electronic hydraulic braking system, the actual feedback capacity of the motor, and the anti-drag torque of the engine; Step S8, performing electro-hydraulic coordinated braking, according to the driver's braking demand and the braking torque actually required to be executed by the motor, the electronic hydraulic braking system and the motor respectively execute corresponding braking torques; Step S9, obtaining motor state parameters, when the motor state is abnormal, executing step S10; Otherwise, step S1 is executed, and the motor state parameter includes the torque following amount; Step S10: perform pure hydraulic braking.

2. The hybrid vehicle regenerative braking control method based on the electronic hydraulic braking system according to claim 1, characterized in that: In step S1, the vehicle operating parameters include vehicle speed, wheel speed, SOC, engine torque, gear, brake switch, power system status, chassis system status, accelerator pedal opening, braking demand, vehicle speed validity, wheel speed validity, engine torque validity, gear validity, brake switch validity, power system status validity, chassis system status validity, accelerator pedal opening validity and braking demand validity. If the above signals all meet the set conditions, the regenerative braking mode is entered and S2 is executed. If at least one signal does not meet the set conditions, step S10 is executed.

3. The hybrid vehicle regenerative braking control method based on the electronic hydraulic braking system according to claim 1, characterized in that: The step S2, entering the regenerative braking working mode, wherein the electronic hydraulic braking system distributes the electro-hydraulic braking force, specifically includes: The electronic hydraulic braking system distributes the electro-hydraulic braking torque according to the driver's braking demand, with electric braking priority.

4. The hybrid vehicle regenerative braking control method based on the electronic hydraulic braking system according to claim 1, characterized in that: The step S3, obtaining the motor speed signal and determining whether the motor speed signal is jittering, specifically includes: A motor speed fluctuation threshold is set, and when the motor speed exceeds the motor speed fluctuation threshold, it is determined that the motor speed signal jitters.

5. The hybrid vehicle regenerative braking control method based on the electronic hydraulic braking system according to claim 1, characterized in that: The step S4, performing filtering optimization processing on the motor speed, specifically includes: Perform Kalman filtering on the motor speed.

6. The hybrid vehicle regenerative braking control method based on the electronic hydraulic braking system according to claim 1, characterized in that: The step S5, calculating the actual feedback capability of the motor based on the motor speed and the motor state after filtering, specifically includes: The motor power limit value is calculated using the following formula: （1） in, Indicates the maximum power of the motor The motor torque allowed under the limit of Indicates the maximum power of the motor. Indicates the motor speed; The motor phase current limit value is calculated by the following formula: （2） in, Indicates the maximum current allowed The motor torque allowed under the limit of represents the motor torque coefficient, Indicates the maximum current allowed; The motor's own efficiency limit is calculated using the following formula: （3） in, Indicates the charging power, Indicates the motor input mechanical power, Indicates the power consumed by the internal resistance, Indicates the internal resistance value, Indicates the motor torque allowed under the limitation of the motor's own efficiency. Indicates the motor speed, When the speed is determined, For If the power is the largest, then we have: （4） According to formula (4), the motor feedback capability curve is obtained.

7. The hybrid vehicle regenerative braking control method based on the electronic hydraulic braking system according to claim 1, characterized in that: The step S9, obtaining the motor state parameters, when the motor state is abnormal, executing step S10, specifically comprising: A preset motor torque following threshold is set; when the torque following amount exceeds the preset motor torque following threshold, the regenerative braking mode is exited, pure hydraulic braking is performed, and step S10 is executed.

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