Exterior Rotor Permanent Magnet Brushless DC Motors Used In Electric Vehicles And Computer Aided Design

As the demand of resource increasing quickly, and the consciousness of environmental protection strengthening continuously, Electric vehicles are increasingly becoming the focus of widespread concern. Electric vehicles as driving motors not only can alleviate the pressure of the oil shortage, but also can reduce air pollution. So this paper is valuable.Firstly, this paper summarizes electric vehicle motors'research significance and its developing situation, analyzes the market of electric vehicles and predicts its trend of development. This paper also compares the permanent magnet brushless DC motor and several other type motors, and then selects the permanent magnet brushless DC motor as the electric vehicle driving motor.Secondly, this paper briefly introduces permanent magnet brushless DC motors, and recommends the structure characteristics of its system composition, then emphatically introduces its ontology, position detector and electronic switch circuit, finally analyzes the operation principle of permanent magnet brushless DC motor.Thirdly, this paper analyzes and discusses the rated voltage, rated current, rated speed, rated torque, and the wheel hub size, according to the characteristic of electric vehicles, and then determines the main technical parameter of the electricity motivation and its requirement. This paper also combining with a small power permanent magnet brushless DC motor enlarges its power and its corresponding size by using motor similar laws, then simulates the motor by using the software of ANSOFT.Fourthly, this paper sets the voltage and the core length as parameter variables in RMxprt according to the range of electric vehicle's parameter requirement, and calculates its Parametric Setup by using of the Optimetrics of ANSOFT, then choose a project which meet the technology requirement of electric vehicles from the optimization result table. This paper also makes a calculation sheet which specially used for exporting the scheme of exterior rotor permanent magnet brushless DC motors.Finally, this paper imports the optimal scheme to the Maxwell 2D,then calculates the motor scheme by using of finite element analysis, separately calculates its no-load and full-load cases of air-gap flux density, and analysis its comparative results. Then it has respectively drawn the outer circuit diagram of permanent magnet brushless DC motor and permanent magnet synchronous motor by using of ANSOFT Circuit Editor. Then calculates the two kinds of electromagnetic torque by using of the "field-road" coupling method. Lastly it concludes that permanent magnet brushless DC motors' electromagnetic torque is 14.56%bigger than permanent magnet synchronous motor under the same condition of efficient material utilization.