| 摘要 |
<P>PROBLEM TO BE SOLVED: To surely perform an expected return operation even if a power failure occurs at any time while always keeping the electric energy of an appropriate amount accumulated in a backup capacitor, and to change the backup capacitor by a current of an appropriate value that causes no load. <P>SOLUTION: The latest capacitance value Cnew of the backup capacitor 16 is periodically measured. Every time the latest capacitance value Cnew is measured, a charging voltage (required charging voltage) VCmin required to return a valve 200 from a preset opening θsp at that time to an emergency opening/closing position (fully closing position, for example) is calculated based on the measured capacitance value Cnew. When the calculated required charging voltage VCmin is higher than a detected voltage VC between terminals, a value of a charging current Ia is determined based on an actual opening θpv of the valve and the preset opening θsp, and the backup capacitor 16 is charged until the voltage VC between terminals reaches the required charging voltage VCmin. <P>COPYRIGHT: (C)2013,JPO&INPIT |
