Design And Optimization For Adjustable-Speed Permanent Magnet Synchronous Motors

Adjustable-speed permanent magnet synchronous motors (ASPMSM) are one kind of permanent magnet synchronous motors (PMSM) with no start-winding and they are started with variable frequency. Since waveform of the induced voltage and input current is sinusoid wave, they are also called permanent magnet synchronous motor of sinusoid wave. Compared with the three-phase asynchronous motor, ASPMSMS have higher efficiency, higher power factor, smaller volume, simpler structure, and have more advantages in servo adjustable-speed system. With the development of power electronic technology, computer technology and the automatic control technology, DSP controller become more and more ordinary and are improved more and more fast, making ASPMSM prosperous in variable frequency system more and more.Firstly, this paper introduces the characteristic, application, stator and rotor structure of ASPMSM, and specially analyses the influences to the performances of ASPMSM with various rotor structures. It introduced the basic analysis theory of ASPMSM and looked up theory related of motor design and design features of ASPMSM and program the ASPMSM CAD system based on magnetic circuit method. And then, to test the accuracy of CAD system, a motor scheme of 50kW,8 poles was calculated by this CAD system. Compared with RMxprt of Ansoft, the CAD system has certain accuracy, basically meet the engineering application.Secondly, Maxwell, the finite design element software of Ansoft Corporation, is used to calculate several parameters (pole-arc coefficient, no-load magnetic flux leakage coefficient, calculated length of core). And then, the values from Maxwell were used by ASPMSM CAD system to ensure the accuracy of the scheme. This paper simulated the scheme in the method of field-circuit and the results of simulation show that magnetic field-road method is more accurate than equivalent magnet circuitFinally, this paper optimized the motor scheme by finite element software, Maxwell of Ansoft. In ASPMSM, permanent magnet materials largely determine the cost of motor, and the cogging torque affects the steadiness of servo motor. Therefore, this paper considers cogging torque and area of permanent magnet as optimal objective. And consider pole embrace, pole offset and thickness of permanent magnet as optimal variable, and choose genetic algorithm as optimization algorithm. After optimization, there is obvious effect that under the condition of ensuring air-gap flux density basically unchanged; the cogging torque and permanent magnetic area have relatively significantly reduced. There is directive significance for actual application.