A method for controlling the coasting energy recovery torque of hybrid electric vehicles

Abstract

A method for controlling the coasting energy recovery torque of a hybrid vehicle comprises the following steps: S1, a vehicle control unit determines the activation condition of the coasting energy recovery torque calculation when the vehicle is in a coasting state: the vehicle control unit determines whether to activate the coasting energy recovery torque calculation according to the key switch state, the handle position, the accelerator pedal opening, the brake pedal opening, and the coasting energy feedback function prohibition request input signal; S2, coasting energy recovery torque factor calculation: the vehicle control unit determines the coasting energy recovery torque factor in the coasting state according to the fuzzy control system; S3, obtaining the coasting energy recovery torque: the vehicle control unit obtains the coasting energy recovery torque by looking up the coasting energy recovery torque two-dimensional table according to the coasting energy recovery torque factor and the set coasting energy feedback intensity level.

Description

Technical Field

[0001] The invention relates to the technical field of hybrid electric vehicles, and in particular to a method for controlling the coasting energy recovery torque of a hybrid electric vehicle. Background Art

[0002] A hybrid vehicle is a vehicle whose drive system is composed of two or more single drive systems that can operate simultaneously. The vehicle's driving power is provided by a single drive system alone or together according to the actual vehicle driving state. Hybrid vehicles use batteries to provide power to the motor, and use the motor to adjust the engine's operating point, which can effectively reduce fuel consumption and emissions and improve the power and economy of the vehicle. At the same time, during motor braking or coasting, hybrid vehicles convert the kinetic energy provided by the motor into electrical energy to charge the power battery, so effective energy recovery and energy management can be performed. Hybrid vehicles have a motor energy feedback function in coasting conditions. The coasting energy feedback function can effectively improve the vehicle's endurance and energy saving effects, thereby improving the performance of hybrid vehicles.

[0003] The existing hybrid vehicle coasting energy recovery torque control method determines whether to enter the coasting energy recovery condition based on the accelerator pedal signal, brake pedal signal, vehicle speed signal and gear position signal, and calculates the recovery torque by looking up a two-dimensional table based on the accelerator pedal and vehicle speed signals. However, this rule-based control method has poor accuracy and adaptability, and cannot effectively achieve real-time control of the recovery torque. Therefore, it cannot effectively ensure the safety and stability of the vehicle in coasting conditions, and the vehicle's coasting energy feedback efficiency is low, and the vehicle's endurance is poor. Summary of the invention

[0004] The purpose of the present invention is to provide a method for controlling the coasting energy recovery torque of a hybrid vehicle in view of the deficiencies in the prior art. The present invention calculates the coasting energy recovery torque factor based on the deceleration, battery charging power, and driving motor speed using a fuzzy control system, and accurately calculates the coasting energy recovery torque in real time based on the coasting energy recovery torque factor and the set coasting energy feedback intensity level, which is beneficial to improving the safety and stability of the vehicle in coasting conditions, improving the vehicle's coasting energy feedback efficiency, and improving the vehicle's endurance.

[0005] The object of the present invention is achieved in that:

[0006] A method for controlling the coasting energy recovery torque of a hybrid vehicle comprises the following steps:

[0007] S1, the vehicle control unit determines the activation condition of the coasting energy recovery torque calculation when the vehicle is in the coasting state: the vehicle control unit determines whether to activate the coasting energy recovery torque calculation according to the key switch state, the handle position, the accelerator pedal opening, the brake pedal opening, and the coasting energy feedback prohibition function request input signal;

[0008] S2, calculation of coasting energy recovery torque factor: the vehicle control unit determines the coasting energy recovery torque factor in the coasting state according to the fuzzy control system;

[0009] S3, obtaining the coasting energy recovery torque: the vehicle control unit obtains the coasting energy recovery torque by looking up the coasting energy recovery torque two-dimensional table according to the coasting energy recovery torque factor and the set coasting energy feedback intensity level.

[0010] In step S1, the activation conditions for coasting energy recovery torque calculation include the following: the key switch state is "ON", the handle position is "D" or "R", the accelerator pedal opening is 0, the brake pedal opening is 0, and the coasting energy feedback function prohibition request is 0.

[0011] In step S2, the coasting energy recovery torque factor calculation steps are as follows:

[0012] S21, variable input: the vehicle control unit calculates the vehicle acceleration according to the vehicle speed change △V within the preset time period △T, and determines whether the acceleration is greater than or equal to 0. If it is satisfied, the coasting energy feedback function is prohibited from being activated. If it is not satisfied, the deceleration is A, and the battery charging power P and the drive motor speed V are obtained from the vehicle control unit as the input of the coasting energy recovery torque factor fuzzy control system;

[0013] S22, variable fuzzification, determine the membership function of input and output:

[0014] The deceleration A is divided into three subsets {X L , X M , X H}, the domain is [0,10], and the membership degree adopts a trapezoidal type, where X L Represents low deceleration, X M Represents medium deceleration, X H Represents high deceleration;

[0015] The battery charging power P is divided into three subsets {Y L , Y M , Y H}, the domain is [0,100], and the membership degree adopts Gaussian type 2, where Y L Represents battery charging power P low, Y M Represents battery charging power P medium, Y HIt means the battery charging power P is high;

[0016] The drive motor speed V is divided into three subsets {Z L , Z M , Z H}, the domain is [0,120], and the membership degree adopts a trapezoidal type, where Z L Indicates that the drive motor speed is low, Z M Indicates that the drive motor speed is medium, Z H Indicates that the drive motor speed is high;

[0017] The coasting energy recovery torque factor K is divided into five subsets {VL, L, M, H, VH}, the domain is [0,1], and the membership adopts Gaussian type, where VL represents that the coasting energy recovery torque factor is zero, L represents that the coasting energy recovery torque factor is small, M represents that the coasting energy recovery torque factor is moderate, H represents that the coasting energy recovery torque factor is large, and VH represents that the coasting energy recovery torque factor is very large;

[0018] S23, generating a fuzzy control rule base: the vehicle control unit obtains a corresponding fuzzy control rule base according to the membership function;

[0019] S24, output fuzzy quantity K: the vehicle control unit obtains the fuzzy quantity K of the coasting energy recovery torque factor according to the input quantity and the fuzzy control rule library;

[0020] S25, defuzzification: Defuzzification of the fuzzy quantity K of the coasting energy recovery torque factor is performed using the center of gravity method. The weight in the center of gravity method is the degree of membership of each fuzzy quantity. The calculation formula is:

[0021]

[0022] Among them, i is the rule, m is the rule item, and u is the membership degree of the corresponding fuzzy quantity.

[0023] The hybrid vehicle coasting energy recovery torque control method of the present invention calculates the coasting energy recovery torque factor according to the deceleration A, the battery charging power P, and the driving motor speed V using a fuzzy control system, and obtains the coasting energy recovery torque in real time and accurately according to the coasting energy recovery torque factor and the coasting energy feedback intensity level set by the user, thereby realizing real-time control of the coasting energy recovery torque, improving the safety and stability of the vehicle in the coasting state, improving the vehicle's coasting energy feedback efficiency, and improving the vehicle's endurance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a flow chart of a method for controlling the coasting energy recovery torque of a hybrid electric vehicle. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention are described in more detail below in conjunction with the drawings in the embodiments of the present invention. The described embodiments are part of the embodiments of the present invention, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present invention, and cannot be simply understood as limitations on the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present invention. The embodiments of the present invention are described in detail below in conjunction with the drawings:

[0026] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present invention.

[0027] A method for controlling the coasting energy recovery torque of a hybrid vehicle comprises the following steps:

[0028] S1, the vehicle control unit determines the activation conditions for the coasting energy recovery torque calculation when the vehicle is in the coasting state: the vehicle control unit determines whether to activate the coasting energy recovery torque calculation according to the key switch state, handle position, accelerator pedal opening, brake pedal opening, and the coasting energy feedback function prohibition request input signal; the coasting energy recovery torque calculation activation conditions include the following: the key switch state is "ON", the handle position is "D" or "R", the accelerator pedal opening is 0, the brake pedal opening is 0, and the coasting energy feedback function prohibition request is 0.

[0029] S2, calculation of coasting energy recovery torque factor: the vehicle control unit determines the coasting energy recovery torque factor in the coasting state according to the fuzzy control system; the calculation steps of the coasting energy recovery torque factor are as follows:

[0030] S21, variable input: the vehicle control unit calculates the vehicle acceleration according to the vehicle speed change △V within the preset time period △T, and determines whether the acceleration is greater than or equal to 0. If it is satisfied, the coasting energy feedback function is prohibited from being activated. If it is not satisfied, the deceleration is A, and the battery charging power P and the drive motor speed V are obtained from the vehicle control unit as the input of the coasting energy recovery torque factor fuzzy control system;

[0031] S22, variable fuzzification, determine the membership function of input and output:

[0032] The deceleration A is divided into three subsets {X L , X M , X H}, the domain is [0,10], and the membership degree adopts a trapezoidal type, where X L Represents low deceleration, X M Represents medium deceleration, X H Represents high deceleration;

[0033] The battery charging power P is divided into three subsets {Y L , Y M , Y H}, the domain is [0,100], and the membership degree adopts Gaussian type 2, where Y L Represents battery charging power P low, Y M Represents battery charging power P medium, Y H It means the battery charging power P is high;

[0034] The drive motor speed V is divided into three subsets {Z L , Z M , Z H}, the domain is [0,120], and the membership degree adopts a trapezoidal type, where Z L Indicates that the drive motor speed is low, Z M Indicates that the drive motor speed is medium, Z H Indicates that the drive motor speed is high;

[0035] The coasting energy recovery torque factor K is divided into five subsets {VL, L, M, H, VH}, and the domain is

[0036] [0,1], the membership adopts Gaussian type, where VL represents that the coasting energy recovery torque factor is zero, L represents that the coasting energy recovery torque factor is small, M represents that the coasting energy recovery torque factor is moderate, H represents that the coasting energy recovery torque factor is large, and VH represents that the coasting energy recovery torque factor is very large;

[0037] S23, generating a fuzzy control rule base: the vehicle control unit obtains a corresponding fuzzy control rule base according to the membership function; the fuzzy control rule base is as shown in Table 1:

[0038] Table 1

[0039]

[0040]

[0041] S24, output fuzzy quantity K: the vehicle control unit obtains the fuzzy quantity K of the coasting energy recovery torque factor according to the input quantity and the fuzzy control rule library;

[0042] S25, defuzzification: Defuzzification of the fuzzy quantity K of the coasting energy recovery torque factor is performed using the center of gravity method. The weight in the center of gravity method is the degree of membership of each fuzzy quantity. The calculation formula is:

[0043]

[0044] Among them, i is the rule, m is the rule item, and u is the membership degree of the corresponding fuzzy quantity.

[0045] S3, obtaining the coasting energy recovery torque: the vehicle control unit obtains the coasting energy recovery torque by looking up the coasting energy recovery torque two-dimensional table according to the coasting energy recovery torque factor and the set coasting energy feedback intensity level. The coasting energy recovery torque two-dimensional table is as shown in Table 2:

[0046] Table 2

[0047]

[0048] Among them, X is the coasting energy feedback intensity, which can be divided into multiple levels. Users can choose different energy recovery intensity levels according to actual driving conditions; K is the coasting energy recovery torque factor.

[0049] The method for controlling the coasting energy recovery torque of a hybrid vehicle of the present invention is that when the vehicle is in a coasting state, that is, at this time, the key switch state is "ON", the vehicle is in a starting state, the handle position is "D" or "R", the gear position of the vehicle is a driving gear or a reverse gear, the accelerator pedal opening is 0 without a driving force, the brake pedal opening is 0 without a braking force, and the coasting energy feedback function request is prohibited to be 0, that is, the coasting energy feedback function request is in an on state, and a coasting energy recovery torque factor is calculated by using a fuzzy control system according to a deceleration A, a battery charging power P, and a driving motor speed V, and the coasting energy recovery torque of the vehicle in the coasting state is obtained in real time and accurately according to the coasting energy recovery torque factor and the coasting energy feedback level set by a user, so as to realize real-time control of the coasting energy recovery torque, improve the safety and stability of the vehicle in the coasting state, improve the coasting energy feedback efficiency of the vehicle, and improve the vehicle endurance.

[0050] The hybrid vehicle coasting energy recovery torque control method of the present invention is a calculation method of the coasting energy recovery torque of a dual-motor hybrid vehicle based on fuzzy control, and the computer program of the calculation method is installed and run in the vehicle control unit.

[0051] The powertrain of a hybrid vehicle that implements the hybrid vehicle coasting energy recovery torque control method of the present invention includes an engine, a clutch, a generator, a transmission, a drive motor, a reducer, drive wheels, and a high-voltage battery (exceeding the safety voltage of 60V and lower than 1000V); the output end of the engine is connected to the input end of the transmission through a clutch, the output end of the transmission is connected to the drive wheels through a reducer, the generator is directly coupled to the input shaft of the transmission through a primary reduction gear, the drive motor is directly coupled to the reducer through a primary reduction gear, and the generator and the drive motor are both electrically connected to the high-voltage battery.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for controlling the coasting energy recovery torque of a hybrid electric vehicle, characterized in that: The steps include: S1, the vehicle control unit determines the activation condition of the coasting energy recovery torque calculation when the vehicle is in the coasting state: the vehicle control unit determines whether to activate the coasting energy recovery torque calculation according to the key switch state, the handle position, the accelerator pedal opening, the brake pedal opening, and the coasting energy feedback prohibition function request input signal; S2, calculation of coasting energy recovery torque factor: The vehicle control unit determines the coasting energy recovery torque factor in the coasting state according to the fuzzy control system. The calculation steps are as follows: S21, variable input: the vehicle control unit calculates the vehicle acceleration according to the vehicle speed change △V within the preset time period △T, and determines whether the acceleration is greater than or equal to 0. If it is satisfied, the coasting energy feedback function is prohibited from being activated. If it is not satisfied, the deceleration is A, and the battery charging power P and the drive motor speed V are obtained from the vehicle control unit as the input of the coasting energy recovery torque factor fuzzy control system; S22, variable fuzzification, determine the membership function of input and output: The deceleration A is divided into three subsets {X L , X M , X H }, the domain is [0,10], and the membership degree adopts a trapezoidal type, where X L Represents low deceleration, X M Represents medium deceleration, X H Represents high deceleration; The battery charging power P is divided into three subsets {Y L , Y M , Y H }, the domain is [0,100], and the membership degree adopts Gaussian type 2, where Y L Represents battery charging power P low, Y M Represents battery charging power P medium, Y H It means the battery charging power P is high; The drive motor speed V is divided into three subsets {Z L , Z M , Z H }, the domain is [0,120], and the membership degree adopts a trapezoidal type, where Z L Indicates that the drive motor speed is low, Z M Indicates that the drive motor speed is medium, Z H Indicates that the drive motor speed is high; The coasting energy recovery torque factor K is divided into five subsets {VL, L, M, H, VH}, the domain is [0,1], and the membership adopts Gaussian type, where VL represents that the coasting energy recovery torque factor is zero, L represents that the coasting energy recovery torque factor is small, M represents that the coasting energy recovery torque factor is moderate, H represents that the coasting energy recovery torque factor is large, and VH represents that the coasting energy recovery torque factor is very large; S23, generating a fuzzy control rule base: the vehicle control unit obtains a corresponding fuzzy control rule base according to the membership function; S24, output fuzzy quantity K: the vehicle control unit obtains the fuzzy quantity K of the coasting energy recovery torque factor according to the input quantity and the fuzzy control rule library; S25, defuzzification: Defuzzification of the fuzzy quantity K of the coasting energy recovery torque factor is performed using the center of gravity method. The weight in the center of gravity method is the degree of membership of each fuzzy quantity. The calculation formula is: Among them, i is the rule, m is the rule item, and u is the membership degree of the corresponding fuzzy quantity; S3, obtaining the coasting energy recovery torque: the vehicle control unit obtains the coasting energy recovery torque by looking up the coasting energy recovery torque two-dimensional table according to the coasting energy recovery torque factor and the set coasting energy feedback intensity level.

2. The method for controlling the coasting energy recovery torque of a hybrid vehicle according to claim 1, characterized in that: In step S1, the coasting energy recovery torque calculation activation conditions include the following: the key switch state is "ON", the handle position is "D" or "R", the accelerator pedal opening is 0, the brake pedal opening is 0, and the coasting energy feedback function prohibition request is 0.

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