| 摘要 |
PURPOSE:To prevent the shutdown of an inverter apparatus by retaining and indicating the maximum value of a load current during the operation of said inverter apparatus. CONSTITUTION:A three-phase induction motor 6 is driven from a three-phase AC power 2 via a converter circuit 3, a smoothing capacitor 4 and an inverter circuit 5. A control circuit for said inverter circuit 5 is composed of a frequency control circuit 8, a differential amplifier circuit 10, an over-current comparison circuit 12, a protective circuit 13, a reset circuit 22, and a load current peak value interface circuit 100. In this case, there is provided an interface circuit 200 which is a load current peak value retaining means by third-fourth operational amplifier 15b-15d, a second capacitor 16b, an analog switch 19, a change- over switch 20 and others. Thus, said second capacitor 16b is charged with a momentary load current, and the maximum value of said current appears at the output terminal of said fourth operational amplifier 15d and is indicated by a load current indicator 21.
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