Patent ID: 7042182

Claim:
An electronically commutated motor having terminals ( 106 , 108 ) for connecting to an AC voltage source ( 11 ); said motor having a stator having at least one winding phase (L 1 , L 2 , . . . Ln); a permanent-magnet rotor magnetically coacting with that stator; a rectifier ( 38 ) which serves to generate, from an AC voltage (U AC ) at the AC voltage source ( 11 ), a pulsing DC operatingvoltage (U B ); a DC link circuit ( 15 ) having a positive lead ( 30 ) and a negative lead ( 32 ), said pulsing DC voltage from said rectifier being applied between said positive and negative leads; a bridge circuit ( 28 ) connected to said positive and negative leads of the DC link circuit ( 15 ) and serving to supply current to the at least one winding phase, said bridge circuit including an N-channel MOSFET ( 52 ) coupled to said negative lead ( 32 ) and a P-channel MOSFET ( 50 ) coupled to said positive lead ( 30 ); and an auxiliary circuit ( 34 , 34 ′) for generating, from the pulsing DC voltage (U B ) at the DC link circuit and from the AC voltage (U AC ), a control voltage (U ST ) for controlling the P-channel MOSFET ( 50 ) into a conductive state, said control voltage (U ST ) being lower than the pulsing DC voltage (U B ) by an amount equal to a predetermined differential voltage (UΔ).