Space Vector PWM for Nine-Phase VSI with Sinusoidal Output Voltage Generation: Analysis and Implementation

Multi-phase machines are nowadays considered for various applications due to the advantages that they offer when compared to their three-phase counterparts. Established three-phase drive control principles can be easily extended to multi-phase drives. However, development of a proper pulse width modulation scheme (PWM) is necessary in order to establish full control over the harmonic content of output voltages generated by multi-phase voltage source inverters (VSIs). This paper presents an analysis of pulse width modulation for a nine-phase VSI, based on space vector approach. Sinusoidal output voltage generation is elaborated and continuous PWM scheme is analysed in the linear region. Detailed implementation steps are presented together with experimental results obtained from a DSP controlled nine- phase VSI supplying a star-connected load.