Method of Decelerating Alternating Current Motor and Inverter Apparatus

摘要

To be able to reduce a speed of an alternating current motor by an inverter apparatus by a time period as short as possible and to control an alternating current motor which is easy to be saturated magnetically by a previously set current or lower such that the inverter apparatus is not stopped by an overcurrent or the alternating current motor is not burned. It is an object of the invention to provide a method and an apparatus capable of reducing a speed of an alternating current motor and capable of shortening a time period of reducing the speed without bringing about a failure by reducing the speed in an overexcited state by making a time constant of a first degree delay filter larger than a time constant in a normal control state, monitoring a current flowing in the alternating current motor and adjusting the time constant in accordance with a current flowing in the alternating current motor in reducing the speed in driving the alternating current motor by a voltage type inverter including a voltage correcting portion for correcting a given voltage instruction by using a value constituted by passing a direct current bus voltage detected value through the first degree delay filter.