Patent ID: 8040094

Claim:
A circuit for use with a stator winding of an electrical machine, the stator winding including a number of coils linked by the same number of points of common coupling, the circuit comprising: an electronic commutator circuit having the same number of switching stages, each switching stage being connected between a respective one of the points of common coupling and first and second main dc lines and including: a first reverse blocking semiconductor power device capable of being turned on and off by gate control having its cathode connected to the first main dc line; and a second reverse blocking semiconductor power device capable of being turned on and off by gate control having its anode connected to the second main dc line; a voltage clamping circuit including: the same number of clamping stages, each clamping stage being connected between a respective one of the points of common coupling and first and second auxiliary dc lines and including a first diode having its cathode connected to the first auxiliary dc line, and a second diode having its anode connected to the second auxiliary dc line; a first capacitor connected between the first main dc line and the first auxiliary dc line; and a second capacitor connected between the second main dc line and the second auxiliary dc line; and means for selectively discharging the first and second capacitors.