Control apparatus for AC motor

Abstract

The purpose of the present invention is to attain a control apparatus for an AC motor, wherein electrical oscillation of an LC filter circuit can be inhibited even when the magnitude of a torque command is small or nearly zero, and driving of an AC motor can be controlled with stability. The control apparatus for an AC motor controls the driving of an AC motor (6), and is provided with a damping control unit (40) that calculates the amount of damping to be executed for inhibiting fluctuation of a capacitor voltage. The damping control unit (40) calculates the fluctuation degree of the capacitor voltage, calculates the amount of damping to be executed on the basis of this fluctuation degree and a prescribed value set as a value within a prescribed range centering around the maximum torque of the AC motor, generates a torque command or a current command for the AC motor (6) on the basis of this amount of damping to be executed, and controls the current flowing through an inverter (4) to change so as to inhibit the fluctuation of the capacitor voltage, on the basis of the torque command or the current command.

Description

technical field [0001] The present invention relates to a control device for an AC motor for driving and controlling the AC motor. Background technique [0002] The technology of using an inverter to drive and control an AC motor has been widely used in the industry. This technology has been widely used in electric railways in the past, but when the above-mentioned system is applied to electric railways powered by direct current, it is known that the DC Electrical oscillation occurs in the LC filter circuit on the side of the capacitor, and the voltage across the capacitor (capacitor voltage) oscillates, making the control of the motor unstable. However, damping control for suppressing the above oscillation is disclosed in the following Patent Document 1 method. [0003] The following patent document 1 discloses a structure in which the damping operation amount, which is the square value of the fluctuation ratio of the capacitor voltage Efc, and the torque command Tm * ar...

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Problems solved by technology

[0009] For example, there is the following problem: if the torque command Tm * is zero, the attenuation operation amount DAMPCN cannot be used to operate the inverter input power Pinv, and when the capacitor voltage Efc oscillates due to interference such as overhead line voltage fluctuations, the performance of suppressing the oscillation of the capacitor voltage Efc is insufficient

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