| 摘要 |
PURPOSE:To suppress the generations of a vibration and a noise by providing oscillating means for outputting carrier of different frequency and selecting means for selecting one carrier from them. CONSTITUTION:3-phase power sources are converted by rectifier into DC, which is converted to PWM output by an inverter of bridge configuration, and supplied to an induction motor. In this case, a carrier controller 10', a carrier selector 13 for sorting the outputs and a selector 14 are provided in the controller to generate a triangular wave signal TR'. The carrier outputs F1-F3 of 3 triangular wave signals of different frequencies are output from the controller 10', selection signals SL1-SL3 are applied from the selector 13 to the selector 14 to select the outputs F1-F3. Thus, when a machine structure including a motor is resonated, a signal which does not cause a resonance out of three types is selected to apply a triangular wave signal TW'. |
