Research On The Drive Control Of Electric Differential For The Electric Vehicle

Electronic vehicle with four in-wheel motors takes full advantage of the characteristics of the drive motor.The car body weight is reduced by leaving out the structure of differential drive and a series of institutions in the conventional cars.In this structure the motor and wheels are designed as a whole.It makes full use of the controllability of the motor and makes the control more accurate and stable.Electronic vehicle with four in-wheel motors makes use of the electronic differential control technology to take the place of the shaft and it distributes the given torque rationally during the electric vehicle normal operation and steering.In this way it can ensure the vehicle steering stability and accuracy and reduce loss of the friction of the tire.On the other hand it also reduces battery consumption.This paper makes a deep research on the electric vehicle driven by in-wheel motors.The main contents of this paper are :First of all,this paper studies the motion model of the automobile and makes the freedom model for three degree motion of the automobile.Meanwhile it analyzes the automobile tire model and the relationship between the automobile slip rate and the coefficient of friction.On the other hand,the yawing angular velocity generator and the car side-slip angle observer are designed.Based on that the differential control stability control scheme for rational distribution of torque is proposed and it can distribute the torque rationally when the vehicle run and counter.This paper sets the differential control simulation model and obtains the stable operation and steering effect.It proves the feasibility of the control scheme.Secondly,this paper analyzes the mathematical model of asynchronous hub motors and illustrates the selection reasons of vector control by comparing different drive schemes of asynchronous motor.The asynchronous motor vector control scheme is designed by using the method of model reference adaptive speed estimation and the voltage space vector modulation SVPWM technology.Through the analysis of the actual operation situation of the electric car,this paper adds soft effect to enhance the startup torque and optimize the control efficiency and starting comfort level when the torque current is given.It gets a good speed following effect through the MATLAB simulation.The validity of the designed control scheme has been proved.Finally,this paper makes an asynchronous motor controller with DSPIC33FJ32GS606 as the main control chip.This controller implements the motor starting under the no-load and load situations.Meanwhile it is also proved that the system achieves the design effect through power experiments on the measurement and the vehicle test.At the end of this paper,it summarizes the research work and analyzes the research achievements and shortcomings.It also puts forward some suggestions for optimization design in the future.