a speed control device , whereby individual motor phases of an electronically commutated multiphase electric motor are supplied via corresponding individual phase shifters from a constant voltage supply unidirectionally and unpulsed during time blocks which are derived from stored time block pulse patterns specific to certain speeds . the speed control device permits setting a variety of speeds with relatively little expense and with low operating losses . the speed control device further provides a simple device for setting intermediate speeds by means of low - frequency switching between at least two time block pulse patterns .