| 摘要 |
In a method for the detection of the rotational position of the rotor of a DC motor with commutator by evaluating the time development of a rotor current signal of the DC motor, said signal comprising a periodic waviness around an average value and comprising current ripples generated by commutation which are superimposed to said waviness, the rotor current signal of a current ripple detector unit (30) is supplied for detecting the current ripples of the rotor current signal. The rotor current signal is further supplied to a waviness detector unit (34) for detecting a half or full wave of the rotor current signal. The current ripple detector unit (30) is arranged to output a current ripple pulse for each detected current ripple. The waviness detector unit (34) is arranged to output a waviness pulse for each period of the waviness. The output signals of both detector units (30,34) are supplied to a logic OR unit (38) for generating a logic signal. Within a period of the rotor current signal, at least one of the detector units (30,34) will output a pulse. Thereby, the logic signal comprises a logic pulse for each period of the rotor current signal.
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