Design And Optimization Of The Controller Of Separately Excited DC Motor Used In Electric Vehicle

As an important means of transport in modern society, vehicle provide great convenience for human beings, however, simultaneously it has also brought serious problems such as environmental pollution and energy shortage. Electric vehicle (EV) are attracting more and more attention and having great potential for development because of the clean energy and widespread sources. And because of the advantages of low cost and driving easily, the low-speed electric vehicle has a good prospect in market.The DC motor covers a major share of low-speed electric vehicles market with large starting torque, simple control methods and superior speed regulation performance. What’s more, the separately excited DC motor is favorably received by the market with the character of flexible control methods and simplicity in flux-weakening implementation. The separately excited DC motor controllers have a wide variety at present, however, there are universal problems as follows:low efficiency of control system and limiting range; poor reliability of controller, such as frequent burning out of motor and damage of switching devices; improvement needed in climbing ability and the stability of exciting current.The objective of this subject is to design a controller which has superior performance of separately excited DC motor used in electric vehicle. This paper has carried on detailed analysis of the drive control system, power electronic supply and control strategy. Study contents, specific works and the conclusions of this topic are as follows:(1) In this thesis, based on a large number of collection and study of literature about low-speed electric vehicles and the drive system of electric cars, the control scheme is determined;(2) Based on the operation principle and control method of separately excited DC motor, the control method of four-quadrant operation and inverter topology are described; (3) Some specific solutions are put forward for the key problems of electric motor and the defects of existing controllers;(4) In this system, a hardware platform based on digital signal processor dsPIC30F4011is constructed. Then the hardware and software of the system are tested by trial operation to verify the superiority of the controller.