Design and Controllability Trade-Off in Dual Three-Phase Winding PMSMs

Designing and controlling dual three-phase motor poses significant challenges. The conventional mathematical model of such motors only considers fundamental components, thereby failing to capture the complete characteristics of the motors. In this study, we propose a comprehensive mathematical model for dual three-phase permanent magnet synchronous motor (PMSM) that incorporates harmonic sub-spaces. Harmonics arising from the internal structure of the motor, such as 6k±1 (k=1,3,5…) order harmonics, are projected onto harmonic sub-spaces through Vector Space Decomposition (VSD) method. This approach effectively decouples the harmonics from the fundamental sub-space. We utilize the proposed VSD method to identify, assess and compare the electromagnetic performance and controllability of dual three-phase motors with fractional-slot concentrated winding (FSCW) and integral-slot distributed winding (ISDW), as well as symmetric and asymmetric dual three-phase windings. Furthermore, the low control bandwidth issue due to PWM and/or sampling frequency was highlighted. Design guidelines are provided to facilitate the design of such motors. To validate our findings, we construct a prototype and present the corresponding experimental results.