Control circuit for asynchronous rotating machine - monitors supply frequency and machine speed to restart if necessary (NL 16.07.82)

摘要

The control circuit changes over (during starting in a frequency range from zero to a given variable limit) from voltage control supported by current control to purely current control, the voltage controller being disconnected. The current amplitude occurring during starting is set between a maximum and zero. The rate at which the frequency changes during starting is also controlled. Whenever the frequency limit is reached a check is made to see whether the machine's speed is following the given frequency or whether the machine has become asynchronous in which case the frequency is reset to zero and the machine restarted.