公开(公告)号：SG87184A1

公开(公告)日：2002-03-19

申请号：SG200005853

申请日：2000-10-12

Applicant: IBM

Inventor： JOHN ALEXANDER KOSKI ,  NHAN BUI

IPC: H02P6/06 ,  H02P6/04 ,  H02P6/08 ,  H02P6/14 ,  G11B15/46 ,  H02K37/00

Abstract: A current mode pulse width modulation (PWM) technique for brushless motors. The present system and method controls a brushless motor by increasing or decreasing motor speed respectively according to the polarity and value of a pulse width modulation (PWM) control signal. The PWM signal varies according to an error signal generated in proportion to the difference between a desired motor current and an actual motor current. A motor current sensor is used to sense an actual motor current being applied to the motor. A current comparator is used to compare the current desired reference signal and the actual current signal and to generate an error signal. A pulse width modulator is used to convert the error signal to a pulse-width modulated error signal. Armature position sensors are used for sensing armature positions of the motor. A commutator circuit receives the pulse-width modulated error signal and the armature positions of the motor. Power switches are coupled to outputs of the commutator and also coupled to the motor. The commutator controls activation and deactivation of the respective power switches based on the corresponding pulse-width modulated error signal to control the motor at a desired motor current that corresponds to the desired reference current signal. The commutator controls the respective power switches to drive the motor in either a more positive, a more negative direction, or in the same manner to respectively increase, decrease, or maintain the motor speed when the error signal correspondingly has a generally positive, negative, or zero value.