Motor control unit e.g. using PWM

摘要

A control unit for an electric motor with a load comprising four switching elements in a bridge where there is a detector for different states of a device, has a changeover device to alternate between a single phase double-sided chopper system and a single-phase single-sided system. In the first case, a pair of switching elements are conducting, triggered by a PWM signal, and the other pair are blocking, depending on whether the detector signal lies above or below a threshold. In the second case, only one of a pair of elements is triggered to be on or off, and the other one is continually conducting whilst the other pair are blocking.