CN103523022B - Hybrid vehicle vehicle speed estimation method - Google Patents

Abstract

The invention discloses a method for estimating the vehicle speed of a hybrid electric vehicle, which solves the application limitation of the existing vehicle speed estimation algorithm due to the use of an acceleration sensor and the problem of inaccurate estimation caused by wheel slippage when ABS, ESP, and TCS act. The hybrid vehicle speed estimation method comprises the following steps: Step 1, signal reading: respectively read the wheel speed signals of the left front wheel, right front wheel, left rear wheel, and right rear wheel of the hybrid vehicle; The signal is converted into a corresponding vehicle speed signal; step 3, vehicle speed estimation algorithm selection: according to the wheel speed error state variable of the four wheels, the motor speed error state variable, the working state variable of TCS, the working state variable of ABS, and the working state variable of ESP Determine the vehicle speed estimation algorithm; step 4, when it is detected that the four wheel speeds are abnormal and the driving motor or engine speed signal is abnormal, directly set the vehicle speed as zero; step 5, calculate the vehicle speed output.

Description

Hybrid Vehicle Speed Estimation Method

technical field

The present invention relates to a vehicle speed estimation method, more precisely, the present invention relates to a hybrid vehicle speed estimation method.

Background technique

In recent years, hybrid electric vehicles have attracted widespread attention in the automotive industry due to their excellent energy-saving and environmental protection effects.

Hybrid electric vehicles adjust the energy distribution ratio between the engine and the motor through the control strategy, so that the engine can work in the optimal area as much as possible, so as to achieve the purpose of energy saving and environmental protection. Vehicle speed is an important input in the control strategy of hybrid electric vehicles. It is not only related to the switching conditions between various working modes of hybrid electric vehicles, but also has a direct relationship with the distribution of power source torque/power in each mode. Therefore, the accuracy of the vehicle speed signal seriously affects the fuel-saving effect of hybrid electric vehicles, and an accurate vehicle speed estimation algorithm for hybrid electric vehicles is particularly important.

There have been some patents for the vehicle speed estimation algorithm. For example, the existing Chinese patent publication number is CN101655504A, and the publication date is February 24, 2010. The invention proposes a vehicle speed estimation method for an adaptive cruise system of a motor vehicle, which uses Kalman filtering algorithm as the core, and calculates the vehicle speed by using the measurement signals of a wheel speed sensor and a longitudinal acceleration sensor. The Chinese patent publication number is CN102009654A, and the publication date is April 13, 2011. The title of the invention is "a method for estimating the longitudinal speed of an all-wheel electric drive vehicle". The patent is a method for estimating the longitudinal speed of an all-wheel electric drive vehicle. It is mainly the vehicle speed estimation based on the Kalman filter space equation structure and the vehicle speed estimation based on the acceleration integral. The above two methods both use the wheel speed sensor to measure the wheel speed and then use the Kalman filter to process the wheel speed signal. At the same time, the acceleration signal integration method is also used to estimate the current vehicle speed in the vehicle speed estimation. Most vehicles are now equipped with anti-lock braking system ABS (Anti-lock Braking System), so the wheel speed signal processed by ABS can be read directly from ABS and then processed simply, without having to use more complicated Cal Mann filtering method; in addition, the acceleration sensor is generally only installed on some mid-to-high-end cars equipped with the electronic stability system ESP (Electronic Stability Program), so the application of the above two methods has certain limitations.

The Chinese patent publication number is CN102539812A, the publication date is July 4, 2012, and the title of the invention is "a method and device for obtaining vehicle speed". According to the situation, the speed of one or two wheels is selected for vehicle speed calculation. However, this invention does not consider the impact of wheel slip on vehicle speed estimation when ABS, ESP, and traction control system TCS (Traction Control System) function, so the estimation of vehicle speed may be inaccurate sometimes.

Contents of the invention

The purpose of the present invention is to solve the limitation of the existing vehicle speed estimation algorithm due to the use of acceleration sensors and the problem of inaccurate estimation caused by wheel slippage when ABS, ESP, and TCS function, and to provide a method specifically for hybrid vehicles. Speed Estimation Algorithm.

In order to solve the problems of the technologies described above, the present invention is achieved by adopting the following technical solutions:

A method for estimating a vehicle speed of a hybrid electric vehicle is provided, the method comprising the following steps:

Step 1. Signal reading: read the wheel speed signals of the left front wheel, right front wheel, left rear wheel, and right rear wheel of the hybrid vehicle respectively;

Step 2. Convert the wheel speed signal into the corresponding vehicle speed signal: if the wheel speed signal read in step 1 is the rotational speed signal in units of r/min or r/s, then according to the formula v=r·ω, where, v represents the speed of the vehicle, r represents the radius of the wheel, and ω represents the angular velocity of the wheel. The wheel speeds of the left front wheel, right front wheel, left rear wheel, and right rear wheel read in the above steps are respectively multiplied by the wheel radius to obtain the corresponding vehicle speed; If the wheel speed signal read in step 1 is the speed signal in km/h or m/s, then the read wheel speed signals are directly equal to the left front wheel, right front wheel, left rear wheel, and right rear wheel corresponding vehicle speed;

Step 3, vehicle speed estimation algorithm selection: select the vehicle speed estimation algorithm according to the wheel speed error state variable of the four wheels, the motor speed error state variable, the working state variable of TCS, the working state variable of ABS, and the working state variable of ESP;

Step 4. When it is detected that the four wheel speeds are abnormal and the driving motor or engine speed signal is abnormal, the vehicle speed cannot be estimated, and the vehicle speed is directly set to zero;

Step 5. Calculating the vehicle speed output: Under different circumstances, use the above-mentioned different vehicle speed estimation methods to estimate the vehicle speed, and finally output the estimated vehicle speed.

According to a method for estimating the vehicle speed of a hybrid electric vehicle provided by the present invention, said step 1 includes the following steps:

1) HCU (Hybridelectricvehiclecontrolunit, hybrid electric vehicle controller) reads the speed and speed error status of the four wheels of the hybrid electric vehicle from the ABS controller, and obtains the wheel speed of the left front wheel, right front wheel, left rear wheel, and right rear wheel. speed and the wheel speed error state variables of the left front wheel, right front wheel, left rear wheel, and right rear wheel;

2) The HCU reads the engine speed signal and the engine speed error state variable from the engine ECU (Engine control unit, engine controller);

3) The HCU reads the motor speed signal and the motor speed error state variable from the motor ECU;

4) The HCU reads the working status of TCS, ABS and ESP from the controllers of TCS, ABS and ESP respectively, and obtains the working status variables of TCS, ABS and ESP.

According to a method for estimating the vehicle speed of a hybrid electric vehicle provided by the present invention, the third step includes: according to the wheel speed error state variable of the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel, the motor speed error state variable, The working state variable of TCS, the working state variable of ABS, and the working state of ESP, choose a method from the maximum wheel speed method, the minimum wheel speed method, the average wheel speed method, and the power source speed method to estimate and calculate the vehicle speed.

According to a method for estimating the vehicle speed of a hybrid electric vehicle provided by the present invention, said step three specifically includes the following steps:

1) Maximum wheel speed method: when the four wheel speed signals are correct and at least one of ABS and ESP is enabled, the maximum wheel speed method is used;

2) Minimum wheel speed method: when the four wheel speed signals are correct and TCS is enabled, the minimum wheel speed method is adopted;

3) Average wheel speed method: when at least one wheel speed is wrong or TCS, ABS, and ESP are disabled, and at least one wheel speed is normal, the average wheel speed method is used;

4) Power source rotation speed method: When the four wheel speeds are detected to be abnormal and the driving motor and engine speed signals are normal, the speed of the driving motor and engine is used to estimate the vehicle speed.

According to a method for estimating the vehicle speed of a hybrid electric vehicle provided by the present invention, the average wheel speed method comprises the following steps:

(1) When the hybrid vehicle is front-wheel drive, the HCU first detects four wheel speed error states:

a. When the HCU detects that at least one of the left and right rear wheels rotates normally, use the rear wheels to estimate the vehicle speed: when the speeds of the left and right rear wheels are both normal, calculate the wheel speed by taking the average value of the two rear wheels; When the speed of the rear wheel is abnormal, calculate the speed of the left rear wheel; when the speed of the right rear wheel is normal and the speed of the left rear wheel is abnormal, calculate the speed of the right rear wheel;

b. When the HCU detects that the speed of the left and right rear wheels is abnormal, use the front wheels to estimate the vehicle speed: when the speed of the left and right front wheels is normal, calculate the wheel speed by taking the average value of the two front wheels; when the speed of the left front wheel is normal, the right front wheel When the speed is abnormal, calculate the wheel speed and take the speed of the left front wheel; when the speed of the right front wheel is normal and the speed of the left front wheel is abnormal, calculate the wheel speed and take the speed of the right front wheel;

(2) When the hybrid electric vehicle is rear-wheel drive, the HCU first detects four wheel speed error states:

a. When the HCU detects that at least one of the left and right front wheels rotates normally, use the front wheels to estimate the vehicle speed: when the speeds of the left and right front wheels are both normal, calculate the wheel speed by taking the average of the two front wheels; when the left front wheel rotates normally, the right When the front wheel speed is abnormal, calculate the wheel speed and take the left front wheel speed; when the right front wheel speed is normal and the left front wheel speed is abnormal, calculate the wheel speed and take the right front wheel speed;

b. When the HCU detects that the speed of the left and right front wheels is abnormal, use the rear wheels to estimate the vehicle speed: when the speed of the left and right rear wheels is normal, calculate the wheel speed by taking the average value of the two rear wheels; when the speed of the left rear wheel is normal, the right rear wheel When the speed is abnormal, calculate the wheel speed and take the speed of the left rear wheel; when the speed of the right rear wheel is normal and the speed of the left rear wheel is abnormal, calculate the wheel speed and take the speed of the right rear wheel;

(3) When the hybrid electric vehicle is four-wheel drive, calculate the wheel speed and take the average value of the wheel speed signals with normal speed signals.

According to a method for estimating the vehicle speed of a hybrid electric vehicle provided by the present invention, the power source rotational speed method includes the following steps:

(1) When the engine is driven alone, the wheel speed v _c =ra _ave ·ω _e /i _e ; where ω _e is the speed of the engine, i _e is the transmission ratio from the engine to the wheels under the current working condition, and _rave is four the average wheel radius of the wheel;

(2) When the motor is driven alone, the wheel speed v _c =ra _ave ·ω _m /i _m ; where ω _m is the speed of the driving motor, and i _m is the transmission ratio from the driving motor to the wheel under the current working condition;

(3) When the engine and motor are jointly driven, the calculated speed is expressed as a linear combination of the engine speed and the drive motor speed, that is, v _c = k _e r _ave ω _e + k _m r _ave ω _m , k _e and k _m is a parameter related to the configuration, and one of k _e and k _m can be set to 0 for the single-shaft parallel configuration and the double-shaft parallel configuration hybrid power system.

Compared with prior art, the beneficial effects of the present invention are:

1. Since the ABS has already filtered the wheel speed signal, the wheel speed signal read from the ABS is directly used to estimate the vehicle speed. Compared with the Kalman filtering of the speed signal measured by the wheel speed sensor in the existing patent, in It is simpler to implement on the basis of ensuring effective processing of signals.

2. The algorithm takes into account the impact of wheel slip on vehicle speed estimation and the error status of each wheel speed signal when ABS, ESP, and TCS are active, and adopts different algorithms for different situations to make wheel slip and wheel speed signal errors, etc. Under the circumstances, the speed of the vehicle can be estimated correctly.

3. When the four wheel speed signals are abnormal, the engine speed and the drive motor speed are used to estimate the current vehicle speed, which reduces the dependence of the vehicle speed estimation algorithm on the wheel speed signals.

Description of drawings

Below in conjunction with accompanying drawing, the present invention will be further described:

Fig. 1 is the flowchart of the method for estimating the vehicle speed of a hybrid electric vehicle proposed by the present invention;

Fig. 2 is the flow chart of front-wheel drive configuration average wheel speed method in the hybrid vehicle speed estimation method that the present invention proposes;

Fig. 3 is the flow chart of rear wheel drive configuration average wheel speed method in the method for estimating the vehicle speed of hybrid electric vehicle proposed by the present invention;

Fig. 4 is the flow chart of four-wheel drive configuration average wheel speed method in the hybrid vehicle speed estimation method that the present invention proposes;

Fig. 5 is a structural schematic diagram of a configuration in the single-axis parallel configuration mentioned in the power source rotation speed method in the method for estimating the vehicle speed of a hybrid electric vehicle proposed by the present invention;

Fig. 6 is a structural schematic diagram of a configuration in the hybrid configuration mentioned in the power source rotation speed method in the method for estimating the vehicle speed of a hybrid electric vehicle proposed by the present invention;

Fig. 7a-Fig. 7g are the vehicle speed estimation signal diagrams of the embodiment of the method for estimating the vehicle speed of the hybrid electric vehicle proposed by the present invention;

Fig. 7a is the wheel speed of the left rear wheel and the wheel speed error state of the embodiment of the hybrid electric vehicle speed estimation method proposed by the present invention;

Fig. 7b is the wheel speed of the right rear wheel and the error status of the wheel speed of the embodiment of the method for estimating the speed of the hybrid electric vehicle proposed by the present invention;

Fig. 7c is the wheel speed of the left front wheel and the wheel speed error state of the embodiment of the method for estimating the speed of the hybrid electric vehicle proposed by the present invention;

Fig. 7d is the wheel speed of the right front wheel and the wheel speed error state of the embodiment of the hybrid electric vehicle speed estimation method proposed by the present invention;

Fig. 7e is the motor speed and the working state of the motor of the embodiment of the hybrid electric vehicle speed estimation method proposed by the present invention;

Figure 7f is the ESP working state of the embodiment of the hybrid electric vehicle speed estimation method proposed by the present invention;

Fig. 7g is the actual vehicle speed and the estimated vehicle speed of the embodiment of the method for estimating the vehicle speed of a hybrid electric vehicle proposed by the present invention;

In the figure: 1. Engine, 2. Elastic coupling, 3. Generator, 4. Clutch, 5. Drive motor, 6. Transmission shaft, 7. Final reducer, 8. Differential, 9. Vehicle frame, 10. Right front wheel, 11. Right half shaft, 12. Left half shaft, 13. Left front wheel, 14. Right rear wheel, 15. Left rear wheel, 16. Chain, 17. Sun gear, 18. Planetary gear, 19. ring gear, 20. planet carrier, 21. planetary gear mechanism.

detailed description

The present invention is described in detail below in conjunction with accompanying drawing:

In the present invention, firstly, the hybrid electric vehicle controller HCU (Hybridelectricvehiclecontrolunit) reads the rotational speed of each wheel and the error state of the rotational speed signal of each wheel from the ABS controller, and reads the rotational speed of the driving motor and the driving motor speed from the driving motor controller MCU (Motorcontrolunit). Motor speed signal error status, read engine speed and engine speed signal error status from engine controller ECU (Engine control unit), read their respective working status from TCS, ABS, ESP respective controllers. Then, the HCU selects different vehicle speed estimation algorithms to estimate the vehicle speed according to the wheel speed error state, the driving motor speed error state, the engine speed error state, and the working state of TCS, ABS, and ESP.

Under different circumstances, based on the rotational speed signals of the above-mentioned right front wheel 10, right rear wheel 14, left rear wheel 15, left front wheel 13, drive motor 5 and engine 1, there are the following four speed estimation algorithms: maximum wheel speed method, minimum wheel speed method, Speed method, average wheel speed method and power source speed method.

Referring to Fig. 1, hybrid vehicle speed estimation method method of the present invention comprises the steps:

1) Signal reading

1.1) The HCU reads the rotation speed and the error status of the four wheels of the hybrid vehicle from the ABS controller, and obtains the wheel speeds of the left front wheel 13, the right front wheel 10, the left rear wheel 15, and the right rear wheel 14 as ω _lf , ω _rf , ω _lr , ω _rr ; the wheel speed error state variables of left front wheel 13, right front wheel 10, left rear wheel 15, and right rear wheel 14 are ERR _lf , ERR _rf , ERR _lr , ERR _rr . When the value of the wheel speed error state variable is equal to 1, it indicates that the corresponding wheel speed is wrong; when the wheel speed error state variable is equal to 0, it indicates that the corresponding wheel speed is correct.

1.2) The HCU reads the engine 1 speed signal ω _e and the engine 1 speed error state variable ERR _e from the engine ECU. When ERR _e =1, it indicates that the engine 1 speed is wrong; when ERR _e =0, it indicates that the engine 1 speed is not wrong.

1.3) The HCU reads the driving motor 5 speed signal ω _m and the driving motor 5 speed error state variable ERR _m from the MCU driving the motor 5 . When ERR _m =1, it indicates that the rotational speed of the driving motor 5 is wrong; when ERR _m =0, it indicates that the rotational speed of the driving motor 5 is correct.

1.4) The HCU reads the working status of TCS, ABS and ESP from the controllers of TCS, ABS and ESP respectively, and obtains the working status variables of TCS, ABS and ESP as ACT _TCS , ACT _ABS and ACT _ESP respectively. When the working state variable is equal to 1, it indicates that the corresponding system is working under this working condition; when the working state variable is equal to 0, it indicates that the corresponding system is not working under this working condition.

2) Convert the wheel speed signal into the corresponding vehicle speed signal

If the wheel speed signals ω _lf , ω _rf , ω _lr , ω _rr read from the ABS controller are rotation speed signals in units of r/min (or r/s, etc.), then according to the formula v=r·ω, ( v, vehicle speed, unit: m/s; r, wheel radius, unit: m; ω, wheel angular velocity, unit: rad/s; the left front wheel 13 and right front wheel read in step 1) signal reading 10. The wheel speeds of the left rear wheel 15 and the right rear wheel 14 are respectively multiplied by their wheel radii to obtain the corresponding vehicle speeds, respectively expressed as v _lf , v _rf , v _lr , v _rr ; if the wheel speeds read from the ABS controller Signals ω _lf , ω _rf , ω _lr , ω _rr are speed signals in units of km/h (or m/s, etc.), and the read wheel speed signals are directly equal to the left front wheel 13 and the right front wheel 10 , the vehicle speeds v _lf , v _rf , v _lr , and v _rr corresponding to the left rear wheel 15 and the right rear wheel 14 .

3) Selection of vehicle speed estimation algorithm

According to the wheel speed error state variables ERR _lf , ERR _rf , ERR _lr , ERR _rr of the four wheels, the driving motor 5 speed error state variable ERR _m , the working state variable ACT _TCS of TCS, the working state variable ACT _ABS of ABS, and the ESP The working state variable ACT _ESP determines the vehicle speed estimation algorithm.

a) Maximum wheel speed method

When the four wheel speed signal signals are correct (that is, the value of the four wheel speed error state variables is 0) and at least one of ABS and ESP is enabled, the maximum wheel speed method is used, that is, when ERR _lf =0&&ERR _rf =0&&ERR When _lr =0&&ERR _rr =0&& (ACT _ABS =1||ACT _ESP =1), calculate the vehicle speed v _c =max (v _lf , v _rf , v _lr , v _rr );

b) Minimum wheel speed method

When the four wheel speed signals are correct and TCS is enabled, use the minimum wheel speed method, that is, when ERR _lf =0&&ERR _rf =0&&ERR _lr =0&&ERR _rr =0&&ACT _TCS =1, calculate the vehicle speed v _c =min(v _lf , v _rf , v _lr , v _rr );

c) Average wheel speed method

When at least one wheel speed is wrong or TCS, ABS, and ESP are disabled, and at least one wheel speed is normal, the average wheel speed method is used, that is, when [(ERR _lf =1||ERR _rf =1|| ERR _lr =1||ERR _rr =1)||(ACT _TCS =0&&ACT _ABS =0&&ACT _ESP =0)]&&[!(ERR _lf =1&&ERR _rf =1&&ERR _lr =1&&ERR _rr =1)], calculate the vehicle speed v _c = v _ave , v _ave is the vehicle speed corresponding to the average wheel speed calculated considering the wheel speed error state, and the specific solution method is as follows:

When using the average wheel speed method to estimate the vehicle speed, in order to avoid the slipping and slipping of the driving wheels from causing errors in the vehicle speed estimation, the speed of the non-driving wheels is preferentially used as the calculated wheel speed.

c1) When the hybrid electric vehicle is front-wheel drive, the processing method is as follows:

(1) The HCU first detects four wheel speed error states, and when at least one of the left rear wheel 15 and right rear wheel 14 detects that the speed is normal, the rear wheels are used to estimate the vehicle speed. When the rotation speeds of the left rear wheel 15 and the right rear wheel 14 are both normal, calculate the wheel speed by taking the average value of the two rear wheels, that is, when ERR _lr =0&&ERR _rr =0, v _c =(v _lr +v _rr )/2; When the rotation speed of the left rear wheel 15 is normal and the rotation speed of the right rear wheel 14 is abnormal, calculate the wheel speed and take the rotation speed of the left rear wheel 15, that is, when ERR _lr =0&&ERR _rr =1, v _c =v _lr ; when the right rear wheel 14 rotation speed Normal, when the 15 speed of the left rear wheel is abnormal, calculate the wheel speed and take the 14 speed of the right rear wheel, that is, when ERR _lr =1&&ERR _rr =0, v _c =v _rr ;

(2) When the HCU detects that the rotation speeds of the left rear wheel 15 and the right rear wheel 14 are both abnormal, the front wheels are used to estimate the vehicle speed. When the speeds of the left front wheel 13 and the right front wheel 10 are normal, calculate the wheel speed by taking the average value of the two front wheels, that is, when ERR _lf =0&&ERR _rf =0&&ERR _lr =1&&ERR _rr =1, v _c =(v _lf +v _rf )/2; when the rotation speed of the left front wheel 13 is normal and the rotation speed of the right front wheel 10 is abnormal, calculate the wheel speed and take the rotation speed of the left front wheel 13, that is, when ERR _lf =0&&ERR _rf =1&&ERR _lr =1&&ERR _rr =1, v _c =v _lf ; when the speed of the right front wheel 13 is normal and the speed of the left front wheel is abnormal, calculate the wheel speed and take the speed of the right front wheel 13, that is, when ERR _lf =1&&ERR _rf =0&&ERR _lr =1&&ERR _rr =1, v _c = _vrf ;

c2) When the hybrid electric vehicle is rear-wheel drive, the processing method is as follows:

(1) HCU first detects four wheel speed error states. When the speeds of the left front wheel 13 and the right front wheel 10 are normal, calculate the wheel speed by taking the average value of the two front wheels, that is, when ERR _lf =0||ERR _rf =0, v _c =(v _lf +v _rf )/ 2. When the rotation speed of the left front wheel 13 is normal and the rotation speed of the right front wheel 10 is abnormal, calculate the wheel speed and take the rotation speed of the left front wheel 13, that is, when ERR _lf =0&&ERR _rf =1, v _c =v _lf ; when the right front wheel 10 The rotation speed of the left front wheel is normal, and the rotation speed of the left front wheel 13 is abnormal, and the calculated wheel speed is taken as the rotation speed of the right front wheel 10, that is, when ERR _lf =1&&ERR _rf =0, v _c =v _rf ;

(2) When the HCU detects that the rotation speeds of the left front wheel 13 and the right front wheel 10 are both abnormal, the rear wheels are used to estimate the vehicle speed. When the rotation speeds of the left rear wheel 15 and the right rear wheel 14 are both normal, calculate the wheel speed by taking the average value of the two rear wheels, that is, when ERR _lf =1&&ERR _rf =1&&ERR _lr =0&&ERR _rr =0, v _c =(v _lr + v _rr )/2; when the rotation speed of the left rear wheel 15 is normal and the rotation speed of the right rear wheel 14 is abnormal, calculate the wheel speed and take the rotation speed of the left rear wheel 15, that is, when ERR _lf =1&&ERR _rf =1&&ERR _lr =0&&ERR _rr =1, v _c =v _lr ; when the rotation speed of the right rear wheel 14 is normal and the rotation speed of the left rear wheel 15 is abnormal, calculate the wheel speed and take the rotation speed of the right rear wheel 14, that is, when ERR _lf =1&&ERR _rf =1&&ERR _lr =1&&ERR _rr =0, v _c =v _rr ;

c3) When the hybrid electric vehicle is four-wheel drive, the processing method is as follows:

Calculate the wheel speed and take the mean value of the wheel speed signal with normal speed signal. That is, when ERR _lf =0&&ERR _rf =0&&ERR _lr =0&&ERR _rr =0, v _c =(v _lf +v _rf +v _lr +v _rr )/4; when ERR _lf =1&&ERR _rf =0&&ERR _lr =0&&ERR _rr =0 When , v _c = (v _rf +v _lr +v _rr )/3; when ERR _lf =0&&ERR _rf =1&&ERR _lr =0&&ERR _rr =0, v _c =(v _lf +v _lr +v _rr )/3; When ERR _lf =0&&ERR _rf =0&&ERR _lr =1&&ERR _rr =0, v _c =(v _lf +v _rf +v _rr )/3; when ERR _lf =0&&ERR _rf =0&&ERR _lr =0&&ERR _rr =1, v _c =(v _lf +v _rf +v _lr )/3; when ERR _lf =1&&ERR _rf =1&&ERR _lr =0&&ERR _rr =0, v _c =(v _lr +v _rr )/2; when ERR _lf =1&&ERR _rf = 0&&ERR _lr =1&&ERR _rr =0, v _c =(v _rf +v _rr )/2; when ERR _lf =1&&ERR _rf =0&&ERR _lr =0&&ERR _rr =1, v _c =(v _rf +v _lr )/2 ;When ERR _lf =0&&ERR _rf =1&&ERR _lr =1&&ERR _rr =0, v _c =(v _lf +v _rr )/2; when ERR _lf =0&&ERR _rf =1&&ERR _lr =0&&ERR _rr =1, v _c =( v _lf +v _lr )/2; when ERR _lf =0&&ERR _rf =0&&ERR _lr =1&&ERR _rr =1, v _c =(v _lf +v _rf )/2; when ERR _lf =0&&ERR _rf =1&&ERR _lr =1&&ERR _rr =1, v _c =v _lf ; when ERR _lf =1&&ERR _rf =0&&ERR _lr =1&&ERR _rr =1, v _c =v _rf ; when ERR _lf =1&&ERR _rf =1&&ERR _lr =0&&ERR _rr =1, v _c =v _lr ; when ERR _lf =1&&ERR _rf =1&&ERR _lr =1&&ERR _rr =0, v _c =v _rr ;

d) Power source speed method

When it is detected that the four wheel speeds are abnormal and the speed signals of the drive motor 5 and engine 1 are normal, that is, ERR _lf =1&&ERR _rf =1&&ERR _lr =1&&ERR _rr =1&&ERR _m =0&&ERR _e =0, use the drive motor 5 and engine 1 The RPM estimated vehicle speed.

When the hybrid electric vehicle is working, according to different working modes, there are several forms of driving the engine 1 alone, driving the driving motor 5 alone, and jointly driving the engine 1 and the driving motor 5 . Among them, when the engine 1 is driven alone, v _c =ra _ave ·ω _e /i _e ; where ω _e is the speed of the engine 1, i _e is the transmission ratio from the engine 1 to the wheels under the current working condition, and ra _ave is the four wheels average wheel radius. When the drive motor 5 is driven alone, v _c = _rave ·ω _m /i _m ; where ω _m is the speed of the drive motor 5 , and i _m is the transmission ratio from the drive motor 5 to the wheels under the current working condition. When the engine 1 and the driving motor 5 are jointly driven, the calculated rotational speed must be expressed as a linear combination of the rotational speed of the engine 1 and the rotational speed of the driving motor 5, that is, v _c =k _e r _ave ω _e +k _m r _ave ω _m , k _e and k _m are configuration-dependent parameters. The single-shaft parallel configuration and the double-shaft parallel configuration can set one of k _e and k _m to be 0; take Wuzhoulong’s single-shaft parallel hybrid system configuration as an example, refer to Figure 5, in the joint drive mode, The engine 1 is fixedly connected to the generator 3 through the elastic coupling 2, the generator 3 is connected to the drive motor 5 through the clutch 4, and finally the drive motor 5 is connected to the final drive 7 through the clutch 4, and the power is transmitted through the differential 8, the left half The shaft 12 or the right half shaft 11 transmits to the left front wheel 13 or the right front wheel 10 . According to the configuration in Fig. 5, k _e = 0, k _m is the reciprocal of the speed ratio i ₀ of the main reducer 9, that is, v _c = _rave ·ω _m /i ₀ ; since the engine 1 and the drive motor 5 are coaxial, It can be set that k _m =0, k _e is the reciprocal of the 9 speed ratio i ₀ of the main reducer, and there is v _c = _rave ·ω _e /i ₀ . Using the planetary gear as the configuration of the power coupling device, the determination of k _e and km _m refers to the speed relationship between the input and output of the planetary gear power coupler. Taking the THS (Toyota Hybrid System) configuration used in the first-generation Prius model as an example, refer to Figure 6. The connection relationship of the THS configuration is briefly described as follows: the sun gear 17 is connected to the generator 3; the engine 1 Linked with the planet carrier 20 in the planetary gear mechanism 21; the engine 1 transmits power to the ring gear 19 and the sun gear 17 through the planetary gear 18; Connected with the main reducer 7; according to the speed relationship of the planetary gear structure, the output speed of the THS system ω _out =ω _e ·(1+k)/k-ω _m /k; where ω _m is the speed of the generator 3 , the number of teeth of the k ring gear/the number of teeth of the sun gear. When the method proposed by the present invention is applied to the THS configuration, k _m =1/(k i), k _e =(1+k)/(k i), that is, v _c =ra _ave ω _out / i=rave· _ωe ·(1+k)/(k·i) _-rave · _ωm /( _k ·i), i is the total transmission ratio of the chain transmission mechanism and the final drive.

4) When it is detected that the four wheel speeds are abnormal and the speed signal of the drive motor 5 or engine 1 is abnormal, that is, ERR _lf =1&&ERR _rf =1&&ERR _lr =1&&ERR _rr =1&& (ERR _m =1&&ERR _e =1), it cannot To estimate the vehicle speed, in order to prevent dangerous accidents, the vehicle speed is directly given as zero, that is, v _c =0.

5) Calculate the vehicle speed output

In different situations, the vehicle speed estimation algorithm will use the above-mentioned different vehicle speed estimation methods to estimate the vehicle speed, and finally output the estimated vehicle speed _vc .

In the embodiment, the configuration of the hybrid electric vehicle is shown in Figure 5. In the pure electric mode, the clutch 4 is disengaged, and the drive motor 5 is connected with the final drive 7 through the transmission shaft 6, and the power is transmitted to the left and right sides via the differential 8. The half shaft 12 and the right half shaft 11 are finally transmitted to the left front wheel 13 and the right front wheel 10 correspondingly. When the engine is driven alone or combined, the engine 1 is fixedly connected to the generator 3 through the elastic coupling 2, the generator 3 is connected to the drive motor 5 through the clutch 4, and finally the drive motor 5 is connected to the final drive 7 through the clutch 4 The power is transmitted to the left half-shaft 12 and the right half-shaft 11 via the differential 8 respectively, and finally to the left front wheel 13 and the right front wheel 10 correspondingly.

According to the configuration characteristics, the engine and the front wheels of the car will be disconnected due to the separation of the clutch, but the drive motor 5 is always connected to the rear wheels. Therefore, the speed of the drive motor 5 is used to estimate the vehicle speed in the power source speed method.

Considering that the error of the wheel speed signals of the four wheels cannot be obtained on the real vehicle in a short period of time, it is difficult to artificially perform fault injection on the wheel speed signal and the speed signal of the driving motor 5 on the real vehicle in the test And there is a certain risk, so this embodiment adopts an offline test to verify the method for estimating the vehicle speed of a hybrid electric vehicle in the present invention. The specific method is as follows:

1) Signal reading

First, through the real vehicle test, use CANanalyzer to read and record the wheel speed signals ω _lf , ω _rf , ω _lr , ω _rr of the four wheels, the speed signal ω _m of the driving motor 5, the ESP working status signal ACT _ESP and the actual vehicle speed signal v.

Then, fault injection is artificially performed. The specific implementation method is as follows: after the _280s , the error state variable ERR _lf of the 13th wheel speed of the left front wheel is set to 1; Set the error state variable ERR _lr of the speed of the left rear wheel 15 to 1, set the error state variable ERR _rr of the speed of the right rear wheel 14 to 1 after 300s, and set the error state variable ERR _m of the speed of the drive motor 5 to 1 after 370s .

2) The wheel speed signal is converted into the corresponding vehicle speed

Since the wheel speed signals ω _lf , ω _rf , ω _lr , and ω _rr read from the ABS controller in this example are speed signals in km/h, each wheel speed signal read is directly equal to the left front wheel 13. Vehicle speeds v _lf , v _rf , v _lr , v _rr corresponding to the right front wheel 10 , left rear wheel 15 , and right rear wheel 14 .

Refer to FIG. 7 for the vehicle speed corresponding to the rotational speed signal of each wheel, the rotational speed error state of each wheel, and the working status signal of ESP.

3) Selection of vehicle speed estimation algorithm

In this example, the vehicle speed estimation algorithm is determined according to the wheel speed error state variables ERR _lf , ERR _rf , ERR _lr , ERR _rr of the four wheels, the driving motor 5 rotational speed error state variable ERR _m , and the ESP operating state variable ACT _ESP .

Referring to Fig. 7, in the first 250s, the wheel speed signals of the four wheels are all correct. Therefore, in the first 250s, when the ESP is working, the maximum wheel speed method is used; when the ESP is not working, the average wheel speed method is used. Since this configuration belongs to the rear-wheel drive configuration, the average value of the two front wheel speeds is used Estimated vehicle speed. Between 250s and 280s, only the speed of the right front wheel 10 is wrong, and at this time, the speed of the left front wheel 13 is used to estimate the vehicle speed. Between 280s and 300s, errors occurred in the speeds of the left front wheel 13 and the right front wheel 10, while the speeds of the left rear wheel 15 and right rear wheel 14 did not appear errors, so the wheel speeds of the two rear wheels were used to estimate the vehicle speed. Between 300s and 350s, only the left rear wheel 15 wheel speed signal of the four wheel speed signals has no error, so the wheel speed of the left rear wheel 15 is used to estimate the vehicle speed. Between 350s and 370s, the wheel speeds of the four wheels were all wrong, and the speed signal of the drive motor 5 was not wrong, so the power source speed method was used to estimate the vehicle speed by the speed of the drive motor 5 . From 370s to 400s, the wheel speed signals of the four wheels and the rotational speed signal of the driving motor 5 all have errors. At this time, effective and reasonable vehicle speed estimation cannot be performed. To ensure safety, the given estimated vehicle speed is 0.

For the comparison chart of the final actual vehicle speed and estimated vehicle speed, please refer to Figure 7. Statistics can effectively estimate the data within the time period of 0-370s. 92.7% of the estimated vehicle speed data have a relative error of less than 5%, and 96.8% of the estimated vehicle speed data The relative error is below 10%. Therefore, the method for estimating the vehicle speed of the hybrid electric vehicle proposed by the present invention is not only simple to implement but also can ensure the accuracy of the vehicle speed estimation.

Claims (6)

1. a hybrid vehicle speed estimation method, is characterized in that, the method comprises the following steps: Step 1, signal reading: respectively read the wheel speed signals of the left front wheel (13), the right front wheel (10), the left rear wheel (15), and the right rear wheel (14) of the hybrid electric vehicle; Step 2. Convert the wheel speed signal into a corresponding vehicle speed signal: If the wheel speed signal read in step 1 is a rotational speed signal in units of r/min or r/s, then according to the formula v=r·ω, where, v represents the speed of the vehicle, unit: m/s; r represents the radius of the wheel, unit: m; ω represents the angular velocity of the wheel, unit: rad/s; the left front wheel (13) and right front wheel (10) read in the above steps , the wheel speeds of the left rear wheel (15) and the right rear wheel (14) are multiplied by their wheel radius respectively to obtain the corresponding vehicle speed; if the wheel speed signal read in step 1 is the speed in km/h or m/s signal, each wheel speed signal read is directly equal to the vehicle speed corresponding to the left front wheel (13), the right front wheel (10), the left rear wheel (15), and the right rear wheel (14); Step 3, vehicle speed estimation algorithm selection: according to the wheel speed error state variable of the four wheels (10, 13, 14, 15), the drive motor (5) speed error state variable, the working state variable of the traction control system TCS, anti-lock brake The working state variables of the braking system ABS and the working state variables of the body electronic stability system ESP select the vehicle speed estimation algorithm; Step 4. When it is detected that the wheel speed error state variables of the four wheels (10, 13, 14, 15) are all judged to be wheel speed errors and the speed error state variables of the drive motor (5) or engine (1) are also judged to be at the speed When it is wrong, that is, when the wheel speeds of the four wheels (10, 13, 14, 15) are abnormal and the speed signal of the drive motor (5) or the engine (1) is abnormal, the vehicle speed cannot be estimated, and the vehicle speed is directly given as zero ; Step 5. Calculating the vehicle speed output: Under different circumstances, use the vehicle speed estimation algorithm selected in the above step 3 to estimate the vehicle speed, and finally output the estimated vehicle speed. 2. a kind of hybrid vehicle speed estimation method as claimed in claim 1, is characterized in that, described step one signal reading comprises the following steps: 1) The hybrid vehicle controller HCU reads the rotation speed and the error state of the rotation speed of the four wheels of the hybrid vehicle from the ABS controller, and obtains the left front wheel (13), the right front wheel (10), the left rear wheel (15), The wheel speed of right rear wheel (14) and the wheel speed error state variable of left front wheel (13), right front wheel (10), left rear wheel (15), right rear wheel (14); 2) The HCU reads the engine (1) speed signal and the engine speed error state variable from the engine controller ECU; 3) The HCU reads the drive motor (5) speed signal and the drive motor (5) speed error state variable from the motor controller MCU of the drive motor (5); 4) The HCU reads the working states of TCS, ABS, and ESP from the TCS, ABS, and ESP controllers respectively, and obtains the working state variables of TCS, ABS, and ESP. 3. a kind of hybrid vehicle speed estimation method as claimed in claim 1 is characterized in that, described step 3 speed estimation algorithm selection comprises: according to left front wheel (13), right front wheel (10), left rear wheel (15), the wheel speed error state variable of the right rear wheel (14), the drive motor (5) rotating speed error state variable, the work state variable of TCS, the work state variable of ABS, the work state of ESP, from the maximum wheel speed method, Choose one of the minimum wheel speed method, average wheel speed method, and power source speed method to estimate and calculate the vehicle speed. 4. a kind of hybrid vehicle speed estimation method as claimed in claim 3 is characterized in that, described selects a kind of method to carry out from maximum wheel speed method, minimum wheel speed method, average wheel speed method, power source rotating speed method The calculation of vehicle speed estimation specifically includes the following steps: 1) Maximum wheel speed method: when the four wheel speed signals are correct and at least one of ABS and ESP is enabled, the maximum wheel speed method is used; 2) Minimum wheel speed method: when the four wheel speed signals are correct and TCS is enabled, the minimum wheel speed method is adopted; 3) Average wheel speed method: when at least one wheel speed is wrong or TCS, ABS, and ESP are disabled, and at least one wheel speed is normal, the average wheel speed method is used; 4) Power source rotational speed method: when the four wheel speeds are detected to be abnormal and the rotational speed signals of the driving motor (5) and the engine (1) are normal, use the rotational speeds of the driving motor (5) and the engine (1) to estimate the vehicle speed. 5. a kind of hybrid vehicle speed estimation method as claimed in claim 4, is characterized in that, described average wheel speed method comprises the following steps: (1) When the hybrid vehicle is front-wheel drive, the HCU first detects four wheel speed error states: a. When the HCU detects that at least one of the left and right rear wheels rotates normally, use the rear wheels to estimate the vehicle speed: when the speeds of the left and right rear wheels are normal, calculate the wheel speed by taking the average value of the two rear wheels; when the left rear wheel (15) rotates Normal, when the speed of the right rear wheel (14) is abnormal, calculate the speed of the left rear wheel (15); when the speed of the right rear wheel (14) is normal, and the speed of the left rear wheel (15) is abnormal, calculate the speed Right rear wheel (14) rotating speed; b. When the HCU detects that the rotation speed of the left and right rear wheels is abnormal, use the front wheels to estimate the vehicle speed: when the rotation speed of the left and right front wheels is normal, calculate the wheel speed by taking the average value of the two front wheels; when the rotation speed of the left front wheel (13) is normal, When the speed of the right front wheel (10) is abnormal, the calculation wheel speed is taken as the speed of the left front wheel (13); Wheel (10) speed; (2) When the hybrid vehicle is rear-wheel drive, the HCU first detects four wheel speed error states: a. When the HCU detects that at least one of the left and right front wheels rotates normally, use the front wheels to estimate the vehicle speed: when both the left and right front wheels rotate normally, calculate the wheel speed by taking the average value of the two front wheels; when the left front wheel (13) rotates Normal, when the speed of the right front wheel (10) is abnormal, calculate the speed of the left front wheel (13); when the speed of the right front wheel (10) is normal and the speed of the left front wheel (13) is abnormal, calculate the speed of the wheel Right front wheel (10) rotating speed; b. When the HCU detects that the rotation speed of the left and right front wheels is abnormal, use the rear wheels to estimate the vehicle speed: when the rotation speed of the left and right rear wheels is normal, calculate the wheel speed by taking the average value of the two rear wheels; when the rotation speed of the left rear wheel (15) is normal, When the speed of the right rear wheel (14) is abnormal, calculate the wheel speed and take the speed of the left rear wheel (15); Wheel (14) rotating speed; (3) When the hybrid electric vehicle is four-wheel drive, calculate the wheel speed and take the mean value of the normal wheel speed signal. 6. a kind of hybrid electric vehicle vehicle speed estimation method as claimed in claim 4 is characterized in that, described power source rotating speed method comprises the following steps: (1) When the engine (1) is driven alone, the wheel speed v _c = r _ave · ω _e /i _e ; where ω _e is the speed of the engine, _ie is the transmission ratio from the engine to the wheels under the current working condition, and r _ave is the average wheel radius of the four wheels; (2) When the drive motor (5) is driven alone, the wheel speed v _c = r _ave ·ω _m /i _m ; where ω _m is the speed of the drive motor (5), and i _m is the drive motor to the wheel under the current working condition transmission ratio; (3) When the engine (1) and the driving motor (5) are jointly driven, the calculated rotational speed is expressed as a linear combination of the rotational speed of the engine (1) and the rotational speed of the driving motor (5), that is, v _c = k _e · r _ave · ω _e +k _m · _rave ·ω _m , k _e and _km are configuration-related parameters, and one of _{k e} and km can be set to 0 for the single-shaft parallel configuration and dual-shaft parallel configuration hybrid power system.