| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To solve the problem that the contact state of a power relay cannot detected normally immediately after changing the contact state of the power relay from an on-state to an off-state because of the large discharge time constant of a smoothing capacitor. <P>SOLUTION: A control means 13 changes the contact state of a relay contact 4a from an on-state to an off-state so that an inverter circuit 8 operates at the minimum level for two cycles of a commercial power supply 1 to cause a smoothing capacitor 7 to discharge, and then detects the state of the relay contact 4a based on a voltage value input from a smoothing capacitor voltage detecting means 10. In this manner, even if the smoothing capacitor 7 having a large capacitance is used, the state of the relay contact 4a can be detected accurately after the passage of a short time of several tens of milliseconds from the point of changing of the contact state of the relay contact 4a from the on-state to the off-state. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
