| 摘要 |
A pulse width modulation system for AC motor drive inverters consists of a ROM for storing data of values of cos theta and cos( theta - pi /3) with respect to a phase theta in the range of electrical angle of 60 DEG , a programmable counter for counting the phase theta , an operational circuit for performing logical operations to evaluate each period of time for which a three phase AC motor is energized in accordance with each switching pattern, and a programmable timer for counting each period of time for which the motor is energized in accordance with each switching pattern. The motor is energized in accordance with each switching pattern for the period of time the data of which is gained at the operational circuit so that three phase output voltage resultant vectors form a circular locus.
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