The paper refers to a novel permanent magnet motor with composite-rotor, to solve the difficulties of extend speed by "flux weakening". The motor rotor consists of two rotor segments with different permanent magnet materials which one has high coercive force and high remnant such as NdFeB and the other has low coercive force characteristics such as AlNiCo. When applying different strength pulses of magnetizing (demagnetizing) current, air gap magnetic fields of the motor could be varied over wide range with regard to a certain value. To achieve the aim, the paper analyzes magnetization process of permanent magnet 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.
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