Mathematical models of three-phase PWM drive motor system noise source

Mathematical models of rectifier and inverter was separately studied since three phase pulse width modulation (PWM) drive motor system had no exact high frequency noise source model for forecasting interference. Based on Fourier Transform and Double Fourier integral, Mathematical models on common mode and differential mode noise source of rectifier and inverter were separately built, which laid a foundation for interference forecast of system. PWM carrier wave and fundamental wave function were described by two independent periodic time function and the action function and let the combined function become integrand of Double Fourier integral. The inner and outer integral limits with sine pulse width modulation were obtained. The simulation and experiment results demonstrate that mathematical model of noise source is valid. So the mathematical models can be used as the excitation source of conducted interference forecast of PWM drive motor system.