Output voltage control of a synchronous generator for ships using compound type digital AVR

This paper deal with field current control method of a synchronous generator (SG) for ships using a compound type digital automatic voltage regulator (AVR) in order to control output voltage of the generator. The compound type digital AVR is composed of a control part to adjust output voltage and an auxiliary power unit to supply power to the field. The control part which generates the PWM switching pattern via the PI controller drives a power MOSFET for bypass to limit the synchronous generator´s field current. The auxiliary power unit is parallel connected to an output terminal of the generator through a reactor and power CT. The residual magnetic flux of synchronous generator provides field current to the exciter through the reactor during the initial driving or no-loading operation and load current supplies field current to the exciter flowing to the power CT when the load is connected on the system. Experimental results demonstrate the digital AVR´s benefits.