非正弦供电十五相感应电机谐波电压确定

Determination of Harmonic Voltages for Fifteen-phase Induction Motors With Non-sinusoidal Supply

通过确定非正弦供电十五相感应电机的3次谐波注入电压,为电机PWM调制提供理论依据。把注入3次谐波电压的十五相感应电机气隙磁动势峰值下降幅度最大作为电机理想运行准则,得到基波磁动势与3次谐波磁动势之间空间位置关系与磁动势幅值间数值关系。以十五相感应电机基波等值电路与3次谐波等值电路为基础并从相应的激磁电流出发,计算基波电压与3次谐波电压有效值,求出3次谐波负幅值点与基波正幅值点间相位差,并通过电机空载实验对计算方法的准确性进行了验证。在额定基波电压下,计算了对应于不同给定转差率的基波激磁电流与3次谐波激磁电流,进而得到3次谐波电压有效值及磁动势波形间相位差,最终通过线性插值来获得任意转差率下的3次谐波电压。

The 3-order harmonic injection voltage of a fifteen-phase induction motor with non-sinusoidal supply is determined, which provides theoretical basis for PWM of the supply voltage. With ideal operation criterion that the peak value of air-gap MMF is of the maximtma descending amplitude established, the spatial location and magnitude relation between fundamental MMF and 3-order harmonic MMF are obtained. Based on the fundamental equivalent circuit and the 3-order harmonic equivalent circuit of the fifteen-phase induction motor, corresponding exciting currents are selected as references to calculate RMS values of the fundamental voltage and the 3-order harmonic voltage, which also yields the phase-angle difference between the negative wave crest of 3-order harmonic MMF and the positive wave crest of the fundamental MMF. The accuracy of the proposed method is verified by no-load experiment of the induction motor. Under the rated fundamental supply voltage, the fundamental exciting currents and the 3-order harmonic exciting currents at different given slips are computed, and then the RMS values of the 3-order harmonic voltages with phase-angle differences between MMF waves are obtained. Finally, the 3-order harmonic voltages at any slips are acquired by the linear interpolation.