Current limiter for chopper circuit - compares load current with reference to operation switch controlling one of push=pull transistors

摘要

The chopper circuit has at least two pushpull transistors used to convert a dc input voltage into an ac output voltage. The current limiter has an auxiliary voltage generator (4) located in the chopper load circuit. A controllable switching device (10) connects the control input of one of the two transistors to the auxiliary voltage generator. The current measuring device (6) measures the current in the load circuit (90). A comparator (1) compares the measured current with a reference voltage (40) generated by the auxiliary voltage generator. The comparator controls the controllable switch. The auxiliary voltage generator consists of a capacitor (43), a limiting resistor (42) and a diode (41). The advantage of the appts. is that the current limiter is independent of external supply voltages.