| 摘要 |
PROBLEM TO BE SOLVED: To reduce the fault of each inverter unit itself, and to eliminate the unbalance between the output current of each inverter, by limiting the output current of each inverter unit by detecting the output current. SOLUTION: The output currents I1-I4 of inverter units 1-4 are limited by means of output current detecting circuit 8-11 which detect the currents I1-I4. When the circuits 8-11 detect output currents which are larger than a set value, output current limiting protective circuits provided to the inverter units turn off a switching element which controls the electric current flowing to a motor M, and keep the switching element in the turned-off state until the output currents 11-14 of the units 1-4 become lower than their hysteresis quantities. As a result, the unbalance between the output current of each inverter unit 1-4 can be eliminated and the fault of each inverter unit 1-4 itself can be reduced. |
