Method and circuit arrangement for limiting an overvoltage
AssigneeEUPEC Europaeische Gesellschaft fur Leistungshalbleiter mbH
InventorsMark Muenzer, Reinhold Bayerer, Peter Kanschat
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Abstract
In order to limit an overvoltage at a parallel circuit of IGBT (3) and freewheeling diode (7), an undesirable current spike is used to switch on the intrinsically turned-off IGBT (3′) during the presence of the current spike precisely to an extent such that a current which counteracts the overvoltage arises in the IGBT/freewheeling diode pair. The oppositely acting current reduces the current gradient in leakage inductances (Lσ) and reduces the undesirable induced overvoltages.
Claims16
A method for limiting an overvoltage at a freewheeling device arranged in parallel with a semiconductor power switch, wherein at least a first and a second semiconductor power switch each parallel-connected with a freewheeling device are connected in series, and an output terminal to an inductive load is arranged between the two, the method comprising the steps of:
- controlling one of the semiconductor power switches into the turned-off state and the other one into the non-turned-off state,
- 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.
A circuit arrangement for limiting an overvoltage at a freewheeling device arranged in parallel with a semiconductor power switch, comprising at least a first and a second semiconductor power switch each parallel-connected with a freewheeling device being connected in series, an output terminal arranged between the first and second semiconductor power switch for coupling with to an inductive load, and a feedback path between the output of each semiconductor power switch and its control terminal.
A circuit arrangement for limiting an overvoltage at a freewheeling device arranged in parallel with a semiconductor power switch, comprising at least a first and a second semiconductor power switch each parallel-connected with a freewheeling device being connected in series, an output terminal arranged between the first and second semiconductor power switch for coupling with to an inductive load, wherein a feedback path is provided between the input and control terminal of a power driver, the feedback path being designed such that it permits the control terminal to be driven up only above a threshold value of the current gradient through the freewheeling device.
Dependencies are inferred from the claim text.