Improved Fault-Tolerant Carrier-Based Modulation for Maximum DC-Link Voltage Utilization in FPSW-PMSM Drive System

Compared to the traditional star topology, the five-phase series-end winding permanent magnet synchronous motor (FPSW-PMSM) presents a unique fault characteristic under an open-circuit fault of the central bridge leg. However, the conventional current-reconstruction-based fault-tolerant strategy, which projects the asymmetric fundamental components onto the x-y subspace, leads to a reduction in DC-link voltage utilization. This letter proposes an improved fault-tolerant carrier-based modulation strategy. The harmonic current references are firstly derived under fault-tolerant conditions. Then, the compensation is applied to the projection of the asymmetric fundamental components in the harmonic subspace. The correction to the conventional method is achieved by reconstructing the post-fault voltage vector distribution, which in turn maximizes the DC-link voltage utilization. Experimental results demonstrate that the proposed strategy improves the DC-link voltage utilization of the drive system by 4.21% and 5.9% under minimum copper loss and maximum torque conditions, respectively.