Method for braking brushless DC motors

摘要

A brushless DC motor has a permanent-magnet rotor (1) and stator windings (R, S, T) arranged in a Y-connection as the rotating-field winding. A DC source (2) is connected via a bridge circuit (3) to the stator windings (R, S, T) in such a way that they are supplied in pulsed manner with DC, so that a rotating field is sustained in the stator within which the rotor (1) rotates. In the case of commutation in the braking process, the stator windings are switched in such a way that the following stator winding (T) is in each case switched on via a current-carrying transistor (T5), while all other transistors (T1-T4, T6) of the bridge circuit (3) remain switched off until the end of the commutation process. The currents (iR, iS) then superimposed in the motor ensure that there does not occur in the motor any undesired current increase, which might lead to demagnetisation of the rotor (1). <IMAGE>