The Electronic Differential Control System For In-wheel Driven Three-wheeled Electric Vehicles

To study on low-power Light Electric Vehicles (LEV) such as three-wheeled electric vehicle in the background of increasing development of electric vehicle (EV) would be a necessity. The study could provide not only a prescient guidance for the development of high-performance electric vehicle, but also a enormous potential market for the expectancy to flexible, convenient, energy saving, environmental protective, economic and durable transportation instruments when people's living standards are greatly improved currently. Despite the three-wheeled electric vehicle products in public are very normal and various, however most of them do not abandon the traditional mechanical transmission and steering device, which therefore cost battery power largely and should be the responsibility for vehicles'inefficiency.This thesis utilizes a dsPIC chip as MCU for three-wheels structure's electronic differential (ED) system which controls the steering, transmission and speed synchronous, as well as driving the permanent magnet brushless DC motor (BLDCM).BLDCM is widespread adopt in low-power speed system such as electric three-wheeled vehicle because of its advantages at high starting torque, speed convenient, simple, high power density and easy to maintain. The paper firstly analyzes and studys on some particular issues of BLDCM driving system in detail. Then we make a brief presentation on both designing ideas and structure of the motor-driven controller.Aim to analyse the three-wheeled vehicle's movement state, the dissertation offers an instruction of classical Ackermann-Jeantand model. After finding out its defect at lack of considering the slip rated while the vehicle is turning, this paper has a in-depth analysis at three-wheeled vehicle's dynamic equations in both straightaway and turning condition, proves a tyre's mathematic model, as well as the driving wheels' torque distribution method. An ED control system, specially for three-wheeled vehicle, based on the slip rate is proposed afterwards.Subsequently, thesis takes slip rate as a reference fuzzy input to control the driving wheels' longitudinal torque. Then it completes the simulation model of ED control system for three-wheeled vehicle in Matlab-Simulink platform. Using this model, the paper demonstrates the superiority of fuzzy control in ED system and well-performance of ED control strategy whether in straight driving condition or in a turn via relevant simulation results, which show the strategy can effectively reduce the rear wheels slip.After the demonstration and simulation analysis in the early, this paper designs an BLDCM driving controller with adopts the ED control system, which is especial for three-wheeled vehicles and uses dsPIC30F4012 as its core. Then this paper successfully carries on experiments of commutation current tracking at a controller embedded in-wheel BLDCM.