Transistorized current controlled pulse width modulated inverter machine

Abstract

An alternating current machine drive system, comprised of an alternating current machine and an inverter configured of a plurality of pairs of transistors with the transistors of each pair coupled in series-aiding fashion and each of the pairs of serially coupled transistors connected across a direct current source, is controlled in accordance with inverter current. The transistors of each inverter transistor pair are alternately rendered conductive to supply alternating current at the inverter output in accordance with a current error signal, proportional to the difference in magnitude between actual inverter phase current and a sinusoidal reference signal, with the conduction state of the transistors of each pair reversing each time the current error signal exceeds an upper and lower hysteresis limit, which limits vary in accordance with actual inverter phase current. Conditioning of inverter output voltage to control machine speed and torque is achieved by varying the sinusoidal reference signal frequency and amplitude, respectively, in accordance with operator commands. Optimum inverter machine drive performance is achieved by regulating the sinusoidal reference signal amplitude and frequency in accordance with a feedback machine torque signal and a feedback machine flux signal, respectively.