Unified Analysis of Winding Connection Sequence in Series-End Winding Topology

The series-end winding topology (SWT) can be seen as an evolution from the open-end winding topology (OWT). Through leg-sharing technology, it has significant advantages in terms of the device count and other features. In this article, for the first time, the rules of winding connection sequence (WCS) in SWT with different phase numbers are deduced, and the effect of WCS on the performance of multiphase SWT is studied. An important conclusion is that in an N-phase (N> = 3) SWT, the phase spacing Δn between adjacent connected windings must be relatively prime to N. Especially, in an odd-phase motor, when Δn = 0.5 (N - 1), the dc bus utilization can reach a maximum of two, which is the same as that in OWT. This article also clarifies the similarities and differences between the SWT, OWT, and the N-phase-leg converter topology with no neutral connection, and further clarifies the difference in the rule of WCS between the series connection and the loop connection of the phase winding. For SWT, while ensuring the freedom of full voltage control, the loss caused by the harmonic current component in the multiplexing leg is greatly reduced, especially the zero-axis current component is completely eliminated, which is its unique advantage. The principle and conclusion have been verified by the experiment with a five-phase induction motor and a nine-phase permanent magnet synchronous motor. The proposed method can increase the motor speed range to the same as that in OWT.