Method, electrical circuit arrangements and insulation monitoring devices for a noise-resistant insulation monitoring of an ungrounded power supply system with an inverter

摘要

The invention relates to methods, electrical circuit arrangements and insulation monitoring devices for a noise-resistant insulation monitoring of an ungrounded power supply system with a converter. Switching frequency interference signals caused by the converter operation are detected and evaluated independently of the detection of a measuring signal in a measured displacement voltage, in order to derive from this an (off) switching signal. In addition, an interference resistance to low-frequency interference components generated by the inverter is achieved by generating these low-frequency interference components from a simulation of a pulse width modulation signal of the inverter and suppressed by subtraction so far that a (frequency) complete monitoring of the insulation resistance is possible.