METHOD AND DEVICE FOR SHIFTING THE COMMUTATION TIME OF A SENSORLESS AND BRUSHLESS DIRECT CURRENT MOTOR
The invention relates to a method for shifting the commutation time of a sensorless and brushless direct current motor(1) whose stator windings are supplied by a multiple phase converter circuit. Said converter circuit contains an output stage control element (2), a commutating logic (3), a phase selector (4) and a phase discriminator (5). The current value of the voltage induced in a currentless phase at an input (46) as established by the phase selector and a reference voltage (Uref) at a second input (47) are supplied to a commutation identification element (6) for comparison. Said reference voltage (Uref) can be modified by a commutation shift (7) according to a particular curve (71). An adjustment value (Ust) is supplied for the commutation shift (7) by an adjustment value calculating element (8), in dependence on the desired speed (nsoll) of the motor. The commutation shift takes place advantageously parabolically. The shifting of commutation in dependence on the desired value provides a high torque and keeps the torque ripple small, even at high speeds and with a heavy load.