1. Method for operating an asynchronous motor comprising a main winding and an auxiliary winding, wherein a start capacitor is connected in series with the auxiliary winding before the asynchronous motor is started up and is disconnected at a point in time, which is to be determined, after the asynchronous motor is started up in that the voltage of the auxiliary winding is measured, at least one mathematical model is used, which models the voltage amplitude of the voltage of the auxiliary winding in relation to time and includes at least one parameter of the dynamic process of the motor starting procedure, wherein the parameter of the dynamic process of the motor starting procedure is calculated on the basis of the mathematical model and the course of the amplitude or the effective value of the measured voltage of the auxiliary winding, and the point in time for disconnecting the start capacitor is determined by means of the determined parameter.