Transient Analysis for Magnetic Circuit of a Novel Synchronous Motor Basing on Controllable Flux

The paper refers to a novel permanent magnet motor with composite-rotor, to solve the difficulties of extend speed by “flux weakening”. The rotor is composed of two rotor segments: one is made of AINiCo magnet and the other of NdFeB. Relying on high coercive force and high remnant magnetic flux density quality of NdFeB, permanent magnet motor could get enough air gap magnetic fields. On the other way, by making using of low coercive force characteristics of AINiCo magnet, die permanent motor could be changed the orientation and strength of magnetization when applying a pulse of magnetizing (demagnetizing) current, thus magnetic flux in air gap could be varied over wide range. To achieve the aim, the paper analyzes magnetization process of permanent magnet and transient magnetic circuit in the motor, and then computes the distribution of air gap magnetic field in different magnetization by using finite element method. The numeral results show the validity of the scheme.