Voltage modulation technique for a five-phase VSI supplying Five-phase series connected two-motor drive

This paper deals with series connection of stator windings and with decoupled dynamic control, it has been introduced recently. The two-motor drive system is supplied from a single five-phase voltage source inverter (VSI) and the machines are controlled using vector control scheme. In literature this drive configuration utilizes current control in the stationary reference frame so current fed machine models are employed and the current regulated PWM multi-phase inverter replicates the current references. If current control is to be implemented in the rotating reference frame, a PWM method for the five-phase VSI is needed to generate required reference voltages. This paper proposes voltage modulation scheme to generate five-phase inverter output signals using a simple approach, in such a way that independent and decoupled control of two five-phase series-connected machines is achieved with minimum interaction between the two machines. The proposed method offers significant advantages over the existing space vector PWM. The suggested method generates output voltages that contain two fundamentals at operating frequencies required by the two machines with reduced computational burden on digital signal processor (DSP). The concept is verified by simulation and experimental approach.