METHOD AND APPARATUS FOR DRIVING A POLYPHASE ELECTRONICALLY COMMUTATED ELECTRIC MACHINE AND A MOTOR SYSTEM

The invention relates to a method for operating an electronically commutated electric machine (2). Alternating phase voltage potentials are applied to the phase conductors of the electric machine (2) for commutation, said phase voltage potentials being generated by a pulse-width modulation so that the height of the applied phase voltage potential is determined by a duty cycle (TV) of the pulse width modulation. In order to determine an instant of a zero crossing of a current induced in a phase conductor, a blanking interval (AT) which represents a time slot, is provided, when no phase current potential is applied to the corresponding phase conductor. A first transition time slot (ÜT1) is provided prior to and/or after the blanking interval (AT) during which the progression of the applied phase voltage potential has a defined first gradient during.