Constant speed electric motor drive - is sequentially switched between drive mode and back EMF measurement mode

摘要

Sequential control is used where the controlled variable can be measured and driven at sequential repreated intervals, determined by a clock circuit. A constant speed motor, for example, can be alternately driven, then its back e.m.f. measured, and the drive pulses are arranged to produce a constant speed regardless of load. A measurement and drive phase and their independent circuits can thus be defined. The drive phase circuitry normally comprises a controller and a drive circuit. The measurement phase circuitry comprises a set point generator, comparator, controller and measurement circuit. Feed forward networks, shaping networks storage and nonlinear switching networks may also be incorporated in the measurement phase circuitry.