| 摘要 |
A brushless DC motor has a stator and a rotor. An angle theta<SUB>0 </SUB>between an edge section of the flux barrier on a magnetic pole center side and an edge section on a side for coming in contact with the rib of adjacent flux barrier, with respect to the rotor center, is determined to be equal to or greater than an angle satisfying a following relationship <?in-line-formulae description="In-line Formulae" end="lead"?>theta<SUB>0</SUB>=180°*m/(Pn*f/f<SUB>0</SUB>) (provided 2theta<SUB>0</SUB>-theta<SUB>r</SUB><90°)<?in-line-formulae description="In-line Formulae" end="tail"?> wherein, a frequency of vibration which is to be reduced is represented with f, a pole pair number is represented with Pn, an electrical frequency is represented with f<SUB>0</SUB>=Pn*N, a motor revolution is represented with N, m=1, 3, 5, . . . , an angle of the rib with respect to the rotor center is represented with theta<SUB>r</SUB>, therefore making of motor highly effective and decreasing of the motor acoustic noise are coped with.
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