Carrier synchronisation to reduce common mode voltage in an AC drive

摘要

A method and apparatus for use with a power conversion configuration including a pulse width modulated (PWM) converter, a PWM inverter and master and slave carrier signal generators wherein the master and slave carrier signal generators receive master and slave PWM frequency signals and generate master and slave carrier signals as a function thereof, PWM signals for controlling the converter and the inverter derived by comparing converter and inverter modulating waveforms to converter and inverter carrier signals, respectively, the method comprising the steps of identifying a phase difference between the master and slave carrier signals, using the phase difference to modify subsequent slave carrier signals to substantially conform the slave carrier signal frequency and phase to the master carrier signal frequency and phase and using the master carrier signal and the modified slave carrier signal to generate control signals for the converter and the inverter.