METHOD AND CIRCUIT ARRANGEMENT FOR DETERMINATION OF THE ROTOR POSITION OF A BRUSHLESS DC MOTOR WITHOUT SENSORS

摘要

The invention relates to a method and a circuit arrangement for determination of the rotor position of a brushless DC motor (10) without sensors and to operation thereof with a rotor (12) preferably energized with permanent magnets and a preferably three-phase armature winding (14) with a star connection and a controller (26) for a semiconductor switching device (24) for the successive connection of the windings of the DC motor (10) to a DC supply (16, 18), depending on the rotor position. According to the invention, the controller (26) is supplied with a trigger signal (58), derived from the phase-summated current (I) for the motor (10) to fix the timepoints for the recording of reference values of the voltages (U_i) induced in the individual phases as the time condition for the generation of the commutation signal for the semiconductor switching device (24). The output signal from a summator (34, 36, 38) from the difference of each phase voltage (U_x) and the star point voltage (U_s) is compared in a subsequent comparator (40, 42, 44) with a voltage value for the voltage drop generated by a given phase current (I_ref) across the internal resistance of the phase and the induced voltages (U_ix) and the zero transition points thereof determined therefrom.