The Performance Improvement Research Of Nine-phase Induction Motor Under Harmonic Injection

Compared with traditional three-phase motor, Multiphase motor has many advantages that include high reliability, more control degree of freedom, good fault-tolerant performance, can make use of low voltage power device achieve high power drive system. With the development of power electronics and power electronic devices, the research of multiphase motor and its control system such as the direction has caused more and more attention of scholars, the research of multiphase motor has become an academic hot spot.In this paper,combined with existing multi-phase motor knowledge and research results,induction and derived size and parameters of a nine phase motor from the view of motor design based on a three-phase induction motor. designed the motor windings, and a nine phase induction motor modeling were established in Ansoft / Maxwell.Derived the mathematical model of nine phase induction motor. Researched the windings of nine phase induction motor. Analysis nine phase induction motor with harmonic injection which adopt concentrated and full-pitch windings. Analysis the motor winding magnetic potential harmonic, conclusion only contains 17, 19, 35, 37 apart for 18 period of high harmonics exists by analysis of nine phase induction motor winding current, others times harmonics do not appear. The finite element simulation to verify the theory analysis of nine phase induction motor. Compared with three-phase induction motor, Part of the nine phase induction motor higher harmonic disappeared and avoid the influence of higher harmonic due to the increase in the number of phase, to avoid ripple of motor torque and other influence caused by these high order harmonic, reduce the motor loss of nine phase motor.With winding function of multiphase motor as a starting point, analysis the air-gap mmf(magnetomotive force)of nine phase induction motor,Studied the space-time harmonic of nine phase induction motor. Theoretical analysis proves that, 3, 5, 7times of harmonic can be used by nine phase induction motor to produce useful driving torque. Also, injection these harmonic improved the waveform of the air gap flux density, so as to make the utilization of iron core is improved, increased output torque of the motor, makes the motor performance improved. Give four kinds of solutions to finite element simulation analysis on nine phase induction motor, analyzed the performance of motor under each scheme, proved that keep rated fundamental voltage at the same time injected three times harmonic voltage has the best performance. efficiency improved 1.13% and the torque generated by unit effective current improved 10.4%. The torque generated by the effective current of the unit is increased by 10.4% when increased the fundamental voltage amplitude and injected three times harmonic voltage, the torque of the motor also increased, and the efficiency decline is small.