Synchronous driving of the phase windings of a DC motor according to predefined digitized driving profiles permanently stored, the reading of which is synchronized with the rotor position for optimizing torque characteristics

摘要

Synchronization of the phase switchings in driving a brushless motor with predefined excitation current profiles of substantially nonconstant value, is improved by continuously correcting the rotor position information detected by zero-cross detecting circuits with an updatable delay value. A switching delay counter (PDD) is started by the raw zero-cross pulse (FZC) to determine the generation of a corrected synchronization pulse (RZC). The delay counter is downloaded with a constantly updated value by monitoring the correction signal (SPEEDCONTROL) produced by a speed control loop (PLL) and by incrementing or decrementing the downloaded value in said counter to minimize said correction signal. <IMAGE>