Optimal Third-Harmonic Current Injection for an Asymmetrical Nine-phase PMSM with Non-Sinusoidal back-EMF

Optimal Third-Harmonic Current Injection for Asymmetrical Multiphase Permanent Magnet Synchronous Machines

“…In this case the optimal injection ratio is modified with respect to the symmetrical configuration. This paper extends the results given in [22] by formulating the optimization problem with respect to a generic n-phase PMSM. The approach, by exploiting a proper vector space decomposition (VSD) and the associated rotational transformation, is able to highlight how each current component contributes to the electromagnetic torque and to the average power losses (Section II).…”

“…T is diagonal and effectively performs the decoupling of the different components of the [iVSD] set. On the contrary, for a generic configuration this property is not guaranteed (as shown in [22] for a nine-phase asymmetrical machine).…”

“…invertible and such that [T] = [C] −1 = [C] T ). This property is however not guaranteed in a generic configuration, as exemplified for the asymmetrical nine-phase PMSM in [22].…”

“…On the contrary, the higher-order harmonic injection for asymmetrical winding configurations has been rarely discussed in the literature, the exceptions being [18][19][20][21][22]. While [18] considers the 5 th and the 7 th harmonic injection, in [19] and [20][21] a third harmonic injection has been investigated for a sixphase induction machine and a six-phase PMSM, respectively.…”

“…As an alternative, in [22] the authors have shown how the torque enhancement can be applied in an asymmetrical ninephase PMSM with a single but isolated neutral point. In this case the optimal injection ratio is modified with respect to the symmetrical configuration.…”