Multi-phase inverter analysis

Pole-phase modulation adjusts the pole-phase ratio of an induction machine. This requires a multi-leg, multi-phase inverter. This paper analyzes an n-leg, n-phase inverter and presents several techniques for n-phase space vector pulse width modulation. The n-leg inverter is examined in terms of its (n-1)/2 load circuit configurations. Each load configuration is analyzed to determine the ratio of phase to source current. Next, the waveforms resulting from n-step mode operation for each configuration are presented. There are 2n space-vectors for an n-phase system. These space-vectors can be divided into (n-1)/2 sets which correspond to the inverter's load circuit configurations. Within each set, there exists a maximum magnitude subset of space vectors. This paper presents several SVPWM techniques that are based on the use of these vectors.