| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for reducing magnetic sound of an AC rotary electric machine remarkably as compared with prior art. <P>SOLUTION: With reference to the basic frequency component of a polyphase AC current being conducted to the armature of a polyphase AC rotary electric machine, a frequency of (n-1) order in reverse turn and a harmonic current for reducing magnetic sound of (m+1) order in the same turn are superposed on the polyphase AC current thus damping the n-order, m-order and (n+m) order harmonic components of the basic frequency component in a radial magnetic shaking force generated radially in the core of the AC rotary electric machine. The magnetic sound is generated through combination of circumferential vibration and radial vibration of the core being generated by the magnetomotive force of a rotor and reduction of the radial vibration is especially effective for reducing the magnetic sound. Since the harmonic component of radial magnetic shaking force resulting from the magnetomotive force of the rotor and the stator current has a frequency of 6 or 12 times of the basic frequency, it can be canceled by superposing a current having 5 order frequency in reverse order and 7 order frequency in the same phase order as the basic frequency on the stator current. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
