| 摘要 |
PROBLEM TO BE SOLVED: To maintain a supply of power to a load even if an inverter gets out of order. SOLUTION: When either one of IGBTs 8, 10, 12 and 14 that constitute an inverter gets out of order by a short circuit, an inverter-current detecting element 7 detects that an excessive current is made to flow, and informs a control section 19 of the flow. As an output voltage of a commercial power source 1 drops when the excessive current flows, an input-voltage monitoring section 2 informs the control section 19 that the voltage has dropped. When the input- voltage monitoring section 2 detects a voltage drop of the commercial power source 1, the control section 19 normally starts supply of power from the inverter by breaking a switch 3, but when the excessive current is concurrently detected by the inverter-current detecting element 7, a switch 4 is turned off on since a short-circuit trouble in an IGBT that constitutes the inverter can be assumed. |
