Zero-Sequence Voltage Elimination for Dual-Fed Common DC-Link Open-End Winding PMSM High-Speed Starter-Generator - Part II: Deadtime Hysteresis Control of Zero-Sequence Current

In a common dc-link dual-fed open-end winding permanent magnet synchronous motor (OEW-PMSM) topology, it is well known how the additional flow of a zero-sequence current (ZSC) is permitted. The low zero-sequence impedance characteristic of high-speed machines leads to high-intensity and high-frequency ripple of the ZSC. Therefore, there is a necessity to eliminate the zero-sequence-voltage (ZSV) produced by the two voltage source converters that feed the machine. Furthermore, the non-sinusoidal back electromagnetic force (back EMF) causes the circulation of a third harmonic ZSC. An OEW-PMSM high-speed starter-generator fed by a dual-inverter with a single dc-link is considered. Part I of this paper proposes a modulation for the considered topology able to eliminate instantaneously the ZSV produced. In this paper, a detailed analysis of the deadtime (DT) effect on the ZSV has been carried out and a novel hysteresis control for the ZSC using the DT as a control action is presented. The DT produces a ZSV distortion on the zero-axis that can be used to control the third harmonic ZSC flowing due to the non-sinusoidal machine back EMF.