| 摘要 |
PURPOSE:To improve a follow-up property relating to a target rotational speed and a riseup at the time of restarting by selecting the initialized off time matched with the target rotational speed at the time of switching a blow air amount of a blower motor, and further correcting the off time in accordance with a difference between the actually measured rotational speed and the target rotational speed. CONSTITUTION:Electric power is supplied to a blower motor 3 through a TRIAC 2 from an AC power supply 1. The TRIAC 2 is driven by a switching signal from a microcomputer 4. Here, the TRIAC 2 is turned on via a phase of predetermined delay (off time) from a point of zero power supply voltage to supply electric power to the motor 3 in the rest of time. On the other hand, an actually measured rotational speed of the motor 3 is detected by a hall element 5 and also to compare this detection value with a target value through a microcomputer 4 thus to adjust a switching signal of the TRIAC 2. Here at the time of switching an air amount of the motor 3, the initialized off time matched with the target rotational speed is selected. The off time is corrected in accordance with a difference between the target rotational speed and the actually measured rotational speed. |
