Abstract: Four thyristors are interconnected into an AC bridge circuit. With an AC source connected across inputs to the bridge circuit, a DC motor is connected across outputs of the bridge circuit while the thyristors are operated in the phase control mode to control the power supply to the motor from the AC source. In the absence of the AC source the DC motor is serially connected to a battery across the outputs of the bridge circuit with the thyristors operated in the chopping control mode. Also, in the presence of the AC source, a rectifier bridge including thyristors and diodes can be connected across the battery to exclusively charge it from the AC source.

Abstract: A series combination of thyristor and diode is connected across another series combination of thyristor and diode to form a bridge circuit. Serially connected reactor and capacitor are connected across one of the thyristor in the chopping control mode in the use of a DC source and disconnected from both thyristors in the phase control mode in the use of an AC source in order to drive a DC motor by either of the DC and AC sources. A battery can be connected across the bridge circuit through the DC motor. Either one of the series combinations may be formed of the diode and two thyristors one of which is always connected across the serially connected reactor and capacitor.