Fault-Tolerant Capability and Torque-Speed Measurements of Permanent Magnet Brushless AC Machines

Abstract

In this paper, the fault-tolerant capability in terms of inductance profile of a dual-stator permanent magnet brushless AC machine is presented. Similarly, its power-speed and torque-speed characteristics are also predicted. Special reference is made to the impact of different rotor pole numbers. A 2D-finite element analysis (FEA) procedure is adopted in this work, and the cross-coupling effect of the machine inductances owing to the influence of direct-axis and quadrature-axis currents is also taken into consideration. The results show that, the investigated machine having odd number of rotor poles would exhibit better fault-tolerant capability compared to their counterparts with even number of rotor poles. Further, the machine having 6-stator slots and 13-rotor poles i.e. 6Slots-13P machine has the greatest field-weakening potential owing to its high full-speed to rated speed relation. The studies also show that, the investigated machines have negligible reluctance torque due to their basically unity saliency ratios obtained from the machines’ almost similar quadrature-axis inductance, Lq, and direct-axis inductance, Ld, values.

Keywords

• Direct-axis, quadrature-axis, inductance, power, speed and torque