digital schlupffrequenzregelschaltung for a umrichtergespeiste asynchronous machine

摘要

A control pulse generator is connected to control the gates of thyristor-type inverter circuits supplying an asynchronous dynamo electric machine with a-c power from a d-c source. The slip frequency is determined by a slip frequency pulse generator supplying pulses at a pulse repetition frequency (PRF) representative of a command value, in a feedback circuit including a tachometer generator supplying pulses at a PRF representative of speed of the machine; pulses are applied to a bi-directional counter, the count in the counter controlling the control pulse generator. To prevent simultaneous input to the forward and reverse terminals of the bi-directional counter, a clock pulse source of predetermined frequency which is higher than the highest PRF expected is connected to a time-scanning and division network interconnecting the outputs of the various pulse sources and the counter so that pulses will be applied to the counter only as controlled by the clock pulse source. To enable the control pulse generator to have a wide range, for example between 50 to 30,000 Hz with controlled on-off ratio, a chopper applies positive and negative pulses to an integrator which is connected to a threshold amplifier, providing an output each time the threshold from the integrator is exceeded in either direction, the output controlling the operating rate of the chopper.