| 摘要 |
<p>The control of a multiphase brushless DC motor in a star-configuration without using position sensors for the permanent magnet rotor is carried out by detecting signals having a substantially sinusoidal waverform, which are representative of the difference in voltage between ends of the phase windings and the star-center, selecting the signal relating to a non-excited phase winding, detecting the crossing by the selected signal of a reference voltage level, generating a logic commutation signal upon the crossing by the selected signal of said reference voltage level, and commutating the excitation of the motor by means of said logic commutation signal thus generated and simultaneously masking said representative signals so as to prevent their selection for a time which is sufficiently long to allow the decay of the spikes caused by the last commutation before restarting the cycle. The analysis of the voltage signal of the non-excited phase winding, carried out in the "sinusoidal" section close to the axis of absissas, makes it possible to obtain information on the emf induced by the movement of the permanent rotor on the phase windings of the stator essentially free of terms linked to the inductance and resistance of the windings themselves as well as without the occurrence of spikes due to the previous commutation. Preferably, the masking of the signals takes place by means of a logic masking signal which has a duration equal to a preset fraction of the period of time intervening between the two last successive commutations of the motor, which changes in an essentially gradual manner. The functional diagrams of the various circuit blocks according to a preferred embodiment are illustrated.</p> |
