IPM synchronous machine drive response to symmetrical and asymmetrical short circuit faults

Copyright © 2003 IEEEA closed-form solution is presented for the steady-state response of interior permanent magnet (IPM) synchronous machines to symmetrical short circuits including the effects of q-axis magnetic saturation. Machine response to single-phase asymmetrical short circuits is also investigated. Experimental data are presented to verify predicted behavior for both types of short circuits. It is shown that single-phase asymmetrical short circuit faults produce more severe fault responses with high pulsating torque and a significant threat of rotor demagnetization. A control strategy that purposely transitions such faults into symmetrical three-phase short circuits can minimize the fault severity and associated demagnetization risks. Implications for the design of IPM machines with improved fault tolerance are discussed.Brian A. Welchko, Thomas M. Jahns, Wen L. Soong and James M. Nagashima

Performance assessment of triple redundant nine-phase delta- and wye-connected permanent magnet-assisted synchronous reluctance motor under healthy and fault conditions

In this study, the performance of a triple redundant nine-phase permanent magnet-assisted synchronous reluctance motor with delta-connected windings is comprehensively assessed and compared with that of wye-connected winding under healthy and fault conditions, including open circuit, inter-turn short-circuit and terminal short circuit. The steady-state torque behaviour, loss, efficiency and temperature distribution of the two winding configurations are analysed and compared. It is shown that the delta-connected winding has higher output torque under one phase open-circuit fault and lower inter-turn short-circuit current with three-phase terminal short circuit

Uncontrolled generation in interior permanent magnet machines

Copyright © 2004 IEEEThe movement towards higher power automotive electrical systems has spurred research into low-cost alternators capable of operating over a wide constant power speed range. A promising candidate for this application is a specially designed interior PM machine operating in uncontrolled generation. This paper investigates the modelling and performance of interior PM machines in uncontrolled generation. The hysteresis effect in the machine stator current is experimentally demonstrated and the concept of the voltage-current locus is introduced to explain this. The effect of non-idealities such as magnetic saturation and stator resistance are also examined, to achieve a more accurate steady-state and dynamic modelling of the machine behaviour. The predictions of these models are tested against experimental results.Chong-Zhi Liaw, Wen L. Soong, Brian A. Welchko, and Nesimi Ertugru

Voltage boost by neutral point supply of AC machine

International audienceA new concept of AC motor drive is proposed in this paper. It allows to boost voltage of an AC machine without supplementary components. The main idea is to wisely connect the neutral point of the AC machine to the DC power supply. With some modifications on the control algorithm, the proposed solution allows to supply the AC machine with a higher voltage than with classical inverters. The concept is general for different AC machines and different topologies of inverters. The case study of an induction motor driven by a three-phase two-level inverter is illustrated. In steady state, a factor gain up of 1.7 of maximum RMS voltage can be obtained with the proposed solution compared to a classical scheme. Experimental validation on an induction motor test bench shows the effectiveness of the proposed concept