Patent ID: 7319300

Claim:
A method of ascertaining the value of a motor parameter of an electronically commutated motor during operation thereof, which motor has a stator with a plurality of stator phases and a permanent-magnet rotor coacting with that stator, which rotor induces alternating voltages (U IND ) in the stator phases during operation, a power stage for controlling energization of the stator phases being associated with those stator phases, said method comprising the steps of: during motor operation, interrupting energy delivery to the motor, while the rotor continues to turn; during this substantially currentless state, activating a measurement circuit, in the course of rotation of said rotor through a predetermined rotation range, for a predetermined phase at which the induced voltage reaches a maximum in that predetermined rotor rotation range; with that measurement circuit, measuring the induced voltage, at the predetermined phase at least in the region of that predetermined rotor rotation range; and thereafter switching energy delivery to the motor back on.