| 摘要 |
PURPOSE:To reduce a torque pulsation by intentionally superposing at least one higher harmonic component on a reference signal by a PWM inverter. CONSTITUTION:A phase thetao of fundamental harmonic component of a desired output voltage is inputted to a read only memory (hereinafter referred to as ROM) 11 so that a given voltage Eo including a fifth higher harmonic in a rectangular wave may be obtained. The phase thetao is further inputted to ROM 12 which outputs a triangular wave modulating signal ec. On the other hand, the voltage Eo is multiplied by the desired value lambda of a magnitude of output voltage at a multiplier 2 to output a reference signal eo. A comparator 3 decides on which of the reference signal eo and the modulating signal ec is larger than the other, to give an output S of '1' in case of eo>ec and '0' in case of eo<ec. Further, a switch on the positive side of an inverter is turned ON in case of S=1 and that on the negative side, in case of S=0. In this manner, a torque pulsation with a frequency of the reference signal eo can be eliminated and reduced because a higher harmonic component is superposed on said signal eo.
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