Torque harmonic analysis of induction motor for electric vehicle propulsion

This paper deals with torque harmonic characteristics of induction motor for electric vehicle (EV). For calculate phase stator harmonic leakage flux of a three phase induction motor, an analysis method is determine relationships with stator teeth design. In particular, torque harmonics including EMF harmonics at whole speed ranges are analyzed by the finite element method (FEM). Torque harmonic components are identified with Fourier fast transform (FFT). Torque harmonics are generated due to the different phase windings interaction and they can be reduced by applying a stator teeth design. The electromagnetic field and corresponding harmonics of an electrical machine are calculated using the FEM, the harmonic winding factors show how the torque harmonics can be reduced significantly by good stator teeth design. The novel design methods to compensate the specified torque harmonics are proposed. Then, its effectiveness is clarified according to the representative control strategies for induction motor such as maximum torque per ampere (MTPA) and flux-weakening control.