In order to solve the harmonic issues that exist in multiphase motor systems normally, and find the appreciate approach PWM technology for decreasing the total harmonic distort (THD), this paper studied several PWM technologies which can be used in multiphase motor’s control systems: the maximum vector SVPWM, the space multidimensional vector SVPWM and the carrier-based multiphase PWM, the principle and the implement method of these PWM technologies were given. This paper analyzed the 15-phase permanent magnet synchronous motor control system by Matlab／Simulink model, the simulation results indicated that the motor phase current which used the carrier-based multiphase PWM has lowest content of harmonics and better performance.