Comparative Analysis of Single-Star and Dual-Star Permanent-Magnet Synchronous Machines

Abstract

The performance of a fractional-slot concentrated-winding PMSM with two different winding diagrams, namely, single and dual star, is investigated. Firstly, the air-gap flux density for these two cases in terms of rotating fields is studied, which provides insight into the essential difference between these two windings. Then, a computationally efficient model taking into account saturation and spatial effects using FE-obtained look-up tables is developed. Using the model, the control and the offline design of the controllers are carried out based on the two-axis reference frame model for both machines and the vector space decomposition for dual-star one. The comparison is made in terms of terminal current harmonics, torque ripple, power density, and closed-loop control dynamic performance. It is shown that the dual-star machine has higher power density and less torque ripple, but higher 5th and 7th current harmonics. Moreover, the effect of one imperfection which may come with the dual-star winding diagram, namely imperfect electrical phase shift between the respective currents or voltages of two stars, on the performance of the machine is studied. It is concluded that the imperfection can deteriorate the closed-loop dynamic performance.

Effect of Electrical Steel Punching on the Performance of Fractional-kW Electrical Machines

“…in order to verify the FE model implementation, the average BH curve for a strip with width 6 mm obtained by the FE model and the one calculated analytically using ( 2 In this section the performance of two machines, namely, PMSM and SynRel, based on the developed model in Section II using FE model is analyzed. The PMSM is originally designed for the electric power-assisted steering system in cars [29], while the SynRel machine is derived from the PMSM by keeping the main dimensions, i.e. outer radius and axial length.…”

Iron Losses of Dual-Star PMSMs with Open-Circuit Fault under Fault-Tolerant Control

“…The dual-star winding diagram, otherwise known as asymmetrical six phase, is of special interest as it can be supplied together with threephase off-the-shelf inverters. Moreover, dual-star machines can provide slightly higher torque with lower torque ripple compared to their three-phase counterparts [5].…”

“…This paper aims to cast light on the losses in magnetic core and PMs of a dual-star tooth-wound interior PMSM under FTC strategy with different PhOC faults. The machine under study is designed for electric power-assisted steering system in cars [5]. Moreover, other machine topologies with surface-mounted or interior PMs and distributed winding stator derived from the original machine are studied.…”