Safety function control for an electric machine and method of operating the electric machine

摘要

An apparatus and a method actuate a frequency converter of an electric machine having a safety function, in particular a safe-torque-off (STO) function. Wherein, by a preferably clocked converter circuit, an electrically isolated output voltage is generated from an input voltage, from which output voltage a control signal is generated for the frequency converter for the operation thereof in accordance with standards and for triggering the safety function. An actuation signal is generated for a semiconductor switch which is periodically connected to the input voltage, and the output voltage is limited when the output voltage exceeds a switching threshold.

主权项

1. A method for actuating a frequency converter of an electric machine having a safety function, which comprises the steps of:
generating an electrically isolated output voltage for a normal operation of the frequency converter and for triggering the safety function from an input voltage, the output voltage generated by a clocked converter circuit having a semiconductor switch being intermittently switched to the input voltage; supplying the output voltage to a threshold switch for generating a binary control signal for the frequency converter, the binary control signal activating an operation of the frequency converter when the output voltage exceeds an upper threshold value, the binary control signal triggering the safety function for deactivating the operation of the frequency converter when the output voltage undershoots a lower threshold value; and feeding the output voltage into a control and/or regulation device for adjusting an actuation signal for the semiconductor switch of the converter circuit such that the output voltage is reduced to a target value when the output voltage exceeds a maximum switching threshold, the control and/or regulation device having a comparator for comparing the output voltage to the maximum switching threshold and outputting a further control signal, the further control signal being forwarded by a further switch and the further control signal being used for generating the actuation signal.