| 摘要 |
PROBLEM TO BE SOLVED: To provide an induction motor controller capable of gradually changing the speed of rotation of an induction motor while suppressing a start-up current. SOLUTION: The induction motor controller includes a first coil having a tap connected to a three-phase coil of an induction motor, a first switch connected between a power source for driving the induction motor and the first coil, and a second switch connected to the side where the first switch of the first coil is not connected. It further includes a step-down circuit for generating a voltage having been stepped down from the power supply voltage of the power source by controlling the first and second switches on a tap, a third switch connected between the power source and the three-phase coil, and a first control circuit which controls the first to third switches so that the first and second switches are turned on after the first switch is turned on, and then the three-phase coil is applied with the power supply voltage. The tap is so provided that the tap voltage when the first switch and the second switch are turned on becomes higher than the tap voltage when the first switch is turned on. COPYRIGHT: (C)2011,JPO&INPIT
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