| 摘要 |
PURPOSE: To obtain a PWM controller, a voltage utilization factor thereof is improved, by simple circuit constitution by forming the high voltage command of a triple harmonic from a flux command. CONSTITUTION:The flux command of a triple harmonic is divided into three by a frequency divider 19 and used as a flux command while phase is advanced only by 270 deg. by a phase shifter 16 in the flux command of the triple harmonic. An output from the phase shifter 16 is brought to the same phase as the triple harmonic of a voltage command. The output from the phase shifter 16 is multiplied by thc amplitude of a fundamental-wave voltage command, and a value acquire ed by multiplication is multiplied by a fixed coefficient by a coefficient multiplier 18, thus obtaining the voltage command of thc triple harmonic. The voltage command of the triple harmonic and the fundamental-wave voltage command are added, and employed as a voltage command. Thc voltage command is inputted to a comparator 7a, and compared with an output from a carrier generating circuit 9, thus generating a PWM signal.
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