Research And Design Of Line-Start Single-Phase Permanent Magnet Synchronous Motors Without Starting Windings For Miniature Fan

Single phase asynchronous motor has the advantages of simple structure and running reliable, can be directly starting and, widely used in driving household appliance, especially in driving the low starting torque requirements of the small fan and pump load. But single phase asynchronous motor’s performance indicators are poor, especially low efficiency. With the increasing emphasis on energy conservation and environmental protection, people pay more and more attention to the problem of high loss and low efficiency in motor. So, single-phase permanent magnet synchronous motor turned out.The paper proposes and develops a new type of line-start single-phase permanent magnet synchronous motor which is suitable for driving fans. Comparing with common line-start synchronous motors, this type of motor is not equipped with starting windings. Firstly, the paper introduces the structure and characteristics of the motor, and discusses line-starting conditions of the motor, such as no-load starting, minimizing the motor’s cogging torque and rotor inertia etc.Secondly, according to features, line-starting conditions and tasks of the line-start single-phase permanent magnet synchronous motors without starting windings for miniature fan, completed the electromagnetic design, including the selection of rotor’s structure, material of permanent magnetic, number of slots and the determination of main size etc. Finite element analysis software ANSYS is used to analysis of the motor of 4 slots 6 poles,6 slots 6 poles and 8 slots 6 poles, verified the correctness of the selection of 8 slots and the rationality of the design of motor.And then, this paper describes the mechanism of cogging torque is generated, analytic formula of cogging torque and the expression of cogging torque after the pole shift are given, analyzed the influence of uneven air gap on the cogging torque. Using the finite element software of ANSYS, simulate the cogging torque of line-start single-phase permanent magnet synchronous motors without starting windings for miniature fan with pole shift and non-uniform air gap effect of, determine the best angle and eccentricity, reducing cogging torque effectively.Finally, given the finite element simulation results of the motor using the pole shift and non-uniform air gap, including the waveforms of no-load air gap magnetic flux density, the waveform of no-load back EMF, curve of current after load, curve of speed-time, the curve of torque-time etc. On these basis, according to the electromagnetic design completed 8 slots and 6 poles prototype, the prototype can start smoothly. According to the results of finite element simulation and prototype test, proof the notion of line-start single-phase permanent magnet synchronous motors suitable for driving miniature fan can self starting when without the starting windings is proper. The paper provides reference value for the design of line-start single-phase permanent magnet synchronous motors without starting windings for miniature fan.