| 摘要 |
<p>PROBLEM TO BE SOLVED: To enable detection of voltage fluctuation to compensate power supplied to a motor by detecting fluctuation of direct current level to find the voltage fluctuation with respect to the specified direct current voltage level and to adjust time required for supplying compensation power with respect to the voltage fluctuation. SOLUTION: Two resistors are connected in serial at both ends of a capacitor 21b to output the divided voltage. Since the divided voltage is proportional to the fluctuation of the voltage VDC, which is a voltage of both ends of the capacitor 21b, the detected voltage is multiplied by the proportion to find the whole direct current. A direct current level detecting part 26 detects the voltage level passed through a rectifier part 21 to digitalize in an analog/digital converting part 23. A central processing unit 24 calculates the increase and decrease with respect to the direct current based on the digitalized value and adds or subtracts the compensation to apply the resulting voltage to a pulse width modulation part 22, and to fluctuate ON time of a switching element. Thereby, the average power applied to a motor 25 is constant during a specified period and constant rotational frequency can be obtained.</p> |
