Patent ID: 8212507

Claim:
A method for driving a brushless, electronically commutated electric motor ( 2 ), of a three-strand motor type comprising the steps of providing a line AC voltage (U N ) which is rectified and fed via a slim DC link ( 8 ) with minimum DC link reactance as a DC link voltage (U Z ) to an inverter ( 10 ) that can be driven to supply and commutate the electric motor ( 2 ), a pulsating DC voltage (U G ) initially generated by rectifying the line AC voltage (U N ) is dynamically increased with respect to its instantaneous values in such a manner that the resulting DC link voltage (U Z ) with a reduced ripple lies above a defined limit voltage (U 1 /U 2 ) over time, wherein the pulsating DC voltage (U G ) is converted using a step-up chopper ( 18 ) into the DC link voltage (U Z ), wherein the pulsating DC voltage (U G ) is applied at a pulse duty ratio regulated on the basis of the respective instantaneous DC link voltage (U Z ) to an inductor (L), wherein the DC link voltage (U Z ) is added up via a freewheeling diode (D) and a DC link capacitor (C Zk ) downstream of the inductor (L), and wherein stray inductances (Ls 1 -Ls 3 ) of motor winding heads present in the motor ( 2 ) are used as the inductor (L) for the step-up chopper ( 18 ), and operation of the step-up chopper is performed only in the phases of the commutation control system of the inverter ( 10 ) in which all windings (U, V, W) of the electric motor ( 2 ) are short-circuited, and in that ordinary driving of the windings (U, V, W) for generating torque takes place in the other remaining phases of the commutation.