公开(公告)号：JPH06165576A

公开(公告)日：1994-06-10

申请号：JP31842592

申请日：1992-11-27

Applicant: IBM

Inventor： ENAMI TAKESHI ,  YAMAMOTO SATOSHI

IPC: H02P6/18 ,  H02P6/06 ,  H02P6/08 ,  H02P6/182 ,  H02P6/28 ,  H02P6/02

Abstract: PURPOSE: To provide a driving circuit of a brushless motor wherein power consumption is small, electromagnetic noise and mechanical noise at the time of motor rotation can be reduced, and mounting area is small. CONSTITUTION: According to the outputs of operational amplifiers 5, 6, 7 detecting counter-electromotive forces of phase coils U, V, W, a soft switching waveform shaping circuit 10 and three differential amplifiers 11 control transistors Q2-Q7 and control currents flowing in the phase coils U, V, W. Voltages at the time of driving the transistors Q3, Q5, Q7 are detected with diodes D1-D3. A comparator 22 so controls a switching transistor Q1 and an applying voltage VC that the detected voltage becomes equal to a specified voltage.