Dr. Johannes Heidenhain Gmbh

Simon Graf

Norbert Huber

The voltage of the intermediate circuit of a frequency converter is monitored, while the intermediate circuit is charged via charging resistors. When the voltage has not reached at least a reference voltage during a specific time constant, the charging process is interrupted prematurely. The reference voltage is selected to be considerably lower than the operating voltage of the intermediate circuit. The reference voltage may be less than half of the operating voltage of the intermediate circuit.

Protective circuit for a frequency converter

An evaluation device with an absolute value counter is provided in an incremental position measuring system, which determines the absolute position even in case of loss of the main power supply. The evaluation device is operated by means of an emergency power supply while the main power supply is out. Following the restoration of the main power supply, counting pulses are supplied to a follow-up counter (11) by a pulse emitter, until the follow-up counter has reached the counter reading of the absolute value counter. Two rectangular signals, which are phase-shifted by 90.degree. in relation to each other, are formed as a function of the counting signals, which are present at the evaluation device in the form of output signals.

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Burgkirchen, Germany

Simon Graf