Control and Simulation of a Current-Fed Linear Inductor Machine

A self-controlled, current-fed inverter excited linear inductor machine is described, in which the field current and inverter switching angles are programmed such that the machine operates at constant air-gap flux and unity displacement factor under all operating conditions. The machine can operate in wide speed range and constant predetermined torque is developed during both motoring and regeneration. The control incorporates overlap angle compensation for the inverter and permits modulation of inverter firing angle with resolution of a fraction of a degree. The dynamic d-q axis model of the machine with the power converters and the proposed control strategy has been simulated on a hybrid computer, and static and dynamic performance have been studied in detail. The control circuit has been designed and tested with a 112-kW prototype inductor machine. The experimental results give good agreement with the theory and with simulation.