Importance

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Abstract

The invention relates to a method and apparatus for controlling the current (I1, I2) through a stator winding (L1, L2) of a motor (M) which is supplied with energy from a voltage source (V) via a drive circuit (DL1, DL2). The drive circuit is controllable such as to provide at least three different operational states, of which a first normally signifies increasing or maintained magnitude of the current, a second normally signifies shutting down or decreasing the current comparatively slowly and a third operational state normally signifies shutting down or reducing the current comparatively rapidly or at least quicker than in the second operational state. In a method and apparatus in accordance with the invention the desired value time sequence is sensed, and at least the possibility of control so that entry into the third operational state is limited in time in response to the result of sensing the desired value time sequence. The method and apparatus are primarily intended for micro-stepping of a two-phase stepping motor with permanently magnetized rotor.

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First Claim