Reversible drive for DC motor supplied by rectifier - enables its armature current to be reversed by mechanical switch using control stage

摘要

The switch for reversing the motor is inserted between the motor and rectifier unit, and there is a control stage which consists of digital logic circuits. On reception of a reversing command the system regulates the functioning of the rectifier control unit and operates the reversing switch when the d.c. current zero crossing is signalled. The control stage (25) receives a second signal which shows that the rectifier (1) control pulses are close to the limit of the inverter and the control stage delivers an actuating command to the reversing switch when both signals are present.