| 摘要 |
PROBLEM TO BE SOLVED: To enable an inverter to operate even in case that the voltage of a DC power source is low by operating a switching element in a group of switching elements over the inverter until the last moment when the on- resistance goes up suddenly. SOLUTION: A controller 1 stops a drive control signal to both drive circuits 2a and 2b, thereby turning off each switching element S1-S6 when the differential voltage between the voltage VC (= the second control voltage) detected by the second voltage detector 10b and the voltage VB (= the first control voltage) by the first voltage detector 10a drops to a specified value Vt or under. Moreover, the controller 1 reopens the drive control signal to both drive circuits 2a and 2b, thereby turning on each switching element S1-S6 again when the differential voltage ΔV goes up to a value Vr higher than the specified value Vt after turning off of each switching element S1-S6. |
