A new mathematic description for inverter-AC motor system in step rotating reference frame

In the case of a three-phase AC motor drive system, the output waveform of the static inverter is not sinusoidal, but pulse width-modulated, so the air-gap magnetic field of the motor does not rotate uniformly. Analysis of the system behavior based on a classical approach is rather complicated and possesses considerable errors. This paper provides a step rotating reference frame, abstracted from the physical system and based on the /spl delta/-function, to unite the motor system into whole state equations. This mathematical model not only has an obvious physical meaning, but also facilitates the computer to analyze system behavior and to match or optimize the parameters.<>