Steady-State Characteristics of a Current-Source Inverter/Double-Wound Synchronous Machine System for AC Power Supply

A detailed steady-state analysis of a novel dc-to-ac conversion system used as an ac power source in dc electric railway coaches is presented. This system consists of a current-source inverter, a double-wound synchronous machine, a position sensor, and a control circuit. An equivalent circuit convenient for predicting the steady-state behavior of the system is first derived. Based on this equivalent circuit, the output voltage waveforms are then examined. It is shown that the voltage waveforms are nearly sinusoidal except that narrow spikes are superposed on them during commutation of the thyristors. As to armature reaction in the double-wound synchronous machine, it is shown that a remarkable direct reaction appears which affects the voltage regulation of the system. Finally, a method for keeping the output voltage and frequency constant is discussed.