A method and system for sensorless determination of the orientation of the rotor of an ironless PMSM motor from a known rotor angle is described. The method and system include: specifying a rotor system according to the rotor angle; applying voltage pulses to the phases of the motor in the torque-forming direction of the rotor system; measuring the current in the phases of the motor; determining the expected back EMF along the flux-forming axis, based on the measured current; forming an integral of the expected back EMF by time integration of the expected back EMF along the flux-forming axis and/or a filter-based accumulation function; and determining the orientation of the rotor from the algebraic sign of the integral of the expected back EMF and/or the accumulation function.