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Field aligned starting (FAS) is a technique for starting three-phase cage induction motors on either three-phase or single-phase supply lines under varying load conditions with minimal inrush currents. The technique starts the motor independent of the mains supply with a high transient torque before connecting the spinning motor to the mains. It is imperative to the operation of FAS that the spinning motor be connected to the mains at the correct time. Incorrectly timed mains connection can result in negative transient torques with the severity to slow, or possibly stall the already started motor. As the implementation of FAS is not possible without a predictive mechanism by which the correct moment of mains connection can be found in advance, this paper proposes a simple, low cost, yet effective self-calibrating method which ensures that the timing of the mains connection is correct under all starting conditions. Critical issues vital to a successful self-calibration under transient and varying starting conditions are investigated and presented with both experimental and simulated results to show that self-calibration is an indispensable part of FAS technique. [ABSTRACT FROM AUTHOR]

The paper addresses the bearingless induction motor based on the concept of dual-pole windings, one controlling the motor torque and the other the generated radial forces. Such machines have been investigated experimentally in the past. The paper presents a simulation model capable of investigating the effect of induction-machine design on the generation and control of the radial force. The simulation is based on the dynamic reluctance-mesh field model embedded in vector control systems for the decoupled control of torque, flux and radial force. In the paper, the rotor is constrained by a mechanical bearing so that the radial force is used to cancel the rotor weight to effect 'bearing relief'. The paper summarises the modelling method, investigates the radial force production in both cage and wound rotor machines, and introduces a mixed field orientation method for the decoupled control of the torque and radial forces. Simulations are undertaken showing good generation of radial force under zero speed, acceleration and transient load conditions. [ABSTRACT FROM AUTHOR]