Evaluation device for determining rotational speed of direct-current operated electric motor in motor system, has determination unit determining rotational speed of electric motor based on process of signal evaluated by demodulator

摘要

The device (6) has a signal generator (7) for initializing a periodic control signal, which is supplied to a direct-current operated electric motor (2), such that a resultant periodic signal is generated at the electric motor. A demodulator (9) evaluates and demodulates the resultant signal. A determination unit (10) determines a rotational speed of the electric motor based on the process of the evaluated signal. A filter or a resonant circuit is formed with a decoupling element (4) i.e. inductor, between connections of the electric motor during connecting the device to the electric motor. Independent claims are also included for the following: (1) a motor system comprising a direct-current operated electric motor with a commutator (2) a method for determining a rotational speed of a direct-current operated electric motor.