Multifrequency current control for $n$-phase machines including antiwindup and distortion-free saturation with full DC-Bus utilization

Abstract

Multiphase drives offer important advantages over three-phase ones, e.g., lower per-phase rating and enhanced fault tolerance. For multiphase machines, multifrequency current control (MCC) is often required, e.g., for harmonic cancellation or injection. In certain situations, converter output voltage (OV) saturation occurs, which can cause windup and additional OV distortion. For MCC, obtaining antiwindup and distortion-free OV saturation, with full dc-bus exploitation, entails extra complexity. Recent publications address this problem in three-phase and dual-three-phase (treated as two independent three phases) systems with one and two isolated neutrals, respectively. However, extending such solutions to drives of any phase number n, winding arrangement (symmetrical or asymmetrical), and neutral configuration is not straightforward. This paper proposes a general MCC scheme, including antiwindup and distortion-free OV saturation with full dc-link utilization, for n-phase machines with different winding arrangements (symmetrical or asymmetrical) and neutral configurations. The computational burden required by the proposed antiwindup and saturation strategy is studied; it is concluded that, although it is significant in comparison with the resources needed by the rest of the MCC, the total computational load is acceptable in most of the cases. Experimental results with two multiphase machines are provided, including a comparison with other approaches