| 摘要 |
PURPOSE:To suppress variation of air quantity more than required even if a ventilation resistance is varied by correcting a rotation detection signal in response to a signal of a Sirocco fan. CONSTITUTION:A voltage of a predetermined amplification factor of a voltage applied to a noninverting input terminal is obtained at the output of an operational amplifier 7 in a vent mode. An exciting current substantially proportional to the output voltage flows to a stationary winding 6b, and a rotor 6f starts rotating. As the rotating speed of the rotor 6f approaches a set speed, the output voltage of an F/V converter 13 is increased, while an exciting current due to a driver 160 is reduced, and the set speed is maintained. When the operation turns to a defrosting mode, a Sirocco fan (not shown) attached to the rotor 6f tends to idle. A voltage applied to the noninverting input terminal of the amplifier 7 is reduced as compared with that at the time of vent mode by the closure of a defrosting mode detection switch 14. As a result, the set speed is reduced. The speed rise of a brushless motor 6 is resultantly suppressed. |
