Generalized discontinuous carrier-based PWM modulation scheme for multi-phase converter-machine systems

Using an expanded reference frame transformation expressed in the complex-variable form, the possibilities offered by multi-phase converters, using carrier-based, sine-triangle pulse-width modulation to generate voltages of different frequencies to actuate multi-phase electric machines are set forth. The generalized expressions for the modulation signals, including the neutral voltage component to be compared with the high frequency triangle waveform to synthesize reference voltages for both five and six-phase converter-electric machines are determined. How the inclusion of the neutral voltage affects the modulation signals and the voltage gain and waveform quality is discussed. Some experimental results of synthesized five phase converter voltage waveforms are provided to validate the voltage waveform synthesis using carrier-based generalized (dis)continuous pulse-width modulation for operation in both the under and over- modulation regimes.