Generic Carrier-based PWM Solution for Series-end Winding PMSM Traction System with Adaptative Overmodulation Scheme

The series-end winding PMSM drive system is a new drive topology where the phase windings are connected in series. The generic carrier-based pulse width modulation (CBPWM) solution of series-end winding PMSMs will further promote their applications and avoid the computationally complex space vector PWM in multiphase series-end winding PMSMs. However, the existing carrier-based PWM solution is complex and designed for symmetrical machines. Moreover, the current approach’s lack of the overmodulation method limits its application in the traction system. This paper proposes an improved generic carrier-based PWM solution for series-ending winding PMSMs, which utilizes the vector space decomposition concept to extend the application in both symmetrical and the asymmetrical machines. Firstly, we will introduce the concept of the virtual duty axis and divide the modulation process into two steps, where the leg voltage sequence is initialized with reference phase voltages. Then, the virtual duty cycle is utilized to ensure the feasibility of the leg voltage sequence. Furthermore, we will provide an adaptative overmodulation scheme to ensure the stable fundamental currents in the whole speed range and improve the bus voltage utilization. Finally, the experimental results in three machines verify that the proposed solution can obtain better performance with lower switching frequency and have overmodulation capability.