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Abstract-The objective of this paper is to present a novel means of increasing the dynamic torque per ampere capability of induction machines. The method developed is based on use of an indirect field oriented controller (IFOC) for the induction machine. It is well known that IFOC allows the rotor flux amplitude to be controlled by the d-axis component of stator current. It is also well established that the flux-producing component of the stator current may be controlled independent of the torque-producing component of the stator current. The principal constraint, however, is that the amplitude of the peak current (the vector amplitude) is limited by the power electronic switch ratings. This constraint implies that optimal partitioning of the current components should be possible. Previously used methods have optimized steady state efficiency or steady state torque per ampere. This paper identifies a dynamic method which achieves transient torques over 35% greater than the prior methods. The limitations of the method and its sensitivity to detuning is also examined.

Abstract-Conventional SCR based current source inverters suffer from poor waveform quality due to six step switching. Pulse width modulated current source inverters typically require gate turn off devices with reverse voltage blocking capability which have limited their application. In this paper, a new pulse width modulated current source inverter topology using one gate turn off switch and six SCRs is presented. The converter uses active commutation to realize pulse width modulation in a conventional SCR based current source inverter. Modulation techniques for the proposed inverter, simulation and experimental results are described in the paper. This topology is suitable for high performance, high power applications.

The Holomorphic Embedding Load Flow Method (HELM) has been suggested as an alternative approach to solve load flow problems. However, the current literature does not provide any HELM models that can accurately handle general power networks containing PV and PQ buses of realistic sizes. The original HELM paper dealt only with PQ buses, while a second paper showed how to include PV buses but suffered from serious accuracy problems. This paper fills this gap by providing several models capable of solving general networks, with computational results for the standard IEEE test cases provided for comparison. In addition this paper also presents a new derivation of the theory behind the method and investigates some of the claims made in the original HELM paper.

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