基于最小定子电流纹波有效值的对称六相感应电机载波移相PWM控制

Symmetrical six-phase (S6) motors offer significant advantages over three-phase ones, e.g., fault tolerance and lower per-phase current ratings. Most pulsewidth modulation (PWM) approaches for S6 featuring nearly sinusoidal winding distributions (SWDs) target (ideally) generating sinusoidal voltages in the torque-producing ±² plane with zero-average voltages in the low-impedance xy plane. However, when employing a conventional carrier-based PWM (CBPWM), using a single carrier, substantial stator current ripple (CR) may arise, primarily due to xy switching harmonics. This paper demonstrates that these xy harmonics can be significantly suppressed for S6 SWDs by using a phase-shift PWM (PSPWM) technique with two carriers and phase-shift angle θc = π. For any modulation index, θc = π consistently achieves the lowest stator CR (loss), significantly smaller compared with other θc, including the conventional CBPWM. This is shown to be because when PSPWM with θc = π is implemented, the converter switches with just large αβ space vectors, without xy contributions, while avoiding the complexity of SV PWM. Closed-form formulas for switchingharmonic mapping into subspaces are also derived for S6 and any θc, enabling an in-depth understanding of the switching behavior. Additionally, the dc-link CR is analyzed for several θc. Experimental results with a S6 induction motor validate the theory.