Increasing the operating range of permanent magnet synchronous motors by switching the winding configurations

Abstract

Abstract-This paper presents a holistic approach to determine the effect of online reconfiguration of the motor winding of a synchronous permanent magnet motor resulting in switching the number of turns. The analysis is based on a parameter plane, which predicts the behavior of synchronous machine designs by using only two normalized parameters, the permanent magnet flux linkage and the ratio of the quadrature axis inductance Lq to the direct axis inductance L d . This enables a fast and reliable evaluation of all alternate winding configurations under given constraints. By generating a Pareto front, superior switching configurations can be identified. An exemplary configurable winding machine -implemented in a finite element analysis (FEA) -shows a significant improvement with respect to maximum torque (increase by 20.3%) and usable torque-speed operating range (increase by 5.5%) compared to the best fixed-winding configuration. The contribution demonstrates that this approach is not only applicable for permanent magnet synchronous motors but also for synchronous reluctance, electrically excited synchronous and induction motors.

A Comparative Study of Constant Power Operation Techniques for Low Inductance Machines

“…This technique requires each phase winding to be divided into two sections. During the shift in configuration from series to parallel, the current and voltage per winding are maintained constant [3]. Connection of the windings in parallel leads to a reduction in the number of turns, and therefore a smaller λ pm and L d , as indicated by equations (1) and (2), and thus, higher speed can be achieved.…”

Effects of coil configuration switching, pole-changing and multi-phase windings on permanent magnet synchronous motors

“…ψ PM and ζ consequently span a parameter plane, where the motor characteristics are presented as shown in Fig. 2 [7].…”

“…There are a few examples, where the parameter plane has been adapted to specific issues as for example a variable flux [13], different supply voltage and current ratios [14] or winding configurations [7], [15]. In this contribution, the variables taken into account are the phase number m, the number of windings in series per phase w, the winding factor ξ and the number of pole pairs p. The equations are then normalized to the base values of these variables enabling setting the right relation to each of the different torque-speedcharacteristics, as it was done for w in [7].…”

“…As ψ PM can be calculated by [8] ψ PM = 2 π wξB PM τ p l Fe (7) ψ PM is proportional to w • ξ • 1 p .B PM is the amplitude of the flux density of the permanent magnet.…”

“…With this in mind, efforts were undergone to find ways to improve the PMSM further: Approaches known from grid-connected motors are also proposed for traction drives, as for example star-delta-configuration changes [5] or pole-changing [6] to expand the operating area of these motors. The possibilities of coil switching are extended in [7]. For pole-changing, there are two major approaches to implement the pole-change in the stator winding: on the one hand a winding configuration like a Dahlander winding enabling a simplified change of the pole number of the stator field [8] and on the other hand a change in the phase number leading automatically to a different pole-number.…”