| 摘要 |
PROBLEM TO BE SOLVED: To ensure stabilized conduction insusceptible to disturbance by generating a signal delayed by 90 deg. from the phase voltage based on a signal from a phase voltage sign detecting section and supplying the delay signal from a digital phase shifter to a commutation section. SOLUTION: A digital phase shifter 130 extracts a signal delayed by 90 deg. from the input waveform based on a phase voltage detected at a phase voltage sign detecting section 120 and a mode selecting section 140 makes a decision whether a motor 170 has reached a prescribed speed at the starting stage. Based on a signal from the digital phase shifter 130 or a start signal generating section 110, a conduction signal is then supplied to a commutation section. According to the arrangement, effect of noise intruding at the time of phase voltage measurement is filtered and a stabilized accurate commutation signal can be obtained regardless of load conditions even under a disturbed or transient state. |
