Patent ID: 7315439

Claim:
A method for limiting an overvoltage at a freewheeling device arranged in parallel with a semiconductor power switch, with at least a first and a second semiconductor power switch each parallel-connected with a freewheeling device being connected in series, and with an output terminal arranged between the first and second semiconductor power switch for coupling to an inductive load, the method comprising the steps of: providing a feedback path between output and control terminals of the semiconductor power switch, the feedback path comprising a transformer in series with an amplifier connected to a common input of a push-pull stage of a gate driver connected to the control terminal controlling one of the semiconductor power switches into the turned-off state and the other one into the non-turned-off state, and switching the turned-off semiconductor power switch, at least at the instant of the occurrence of an overvoltage at the associated freewheeling device or during the decay of a current spike, temporarily on to such an extent that a short-time current is generated at the output of the semiconductor power switch.