| 摘要 |
PURPOSE:To suppress an audible electromagnetic sound generated from a motor by variably controlling the frequency of a triangular wave carrier signal for a sine wave control signal within a suitable varying width of a frequency of an integral multiple of the frequency of the control signal. CONSTITUTION:A 3-phase sine wave control signal generator 1 inputs a fre quency command fs of a predetermined output of an inverter and a voltage command, and outputs 3-phase sine wave control signal voltages Vsu-Vsw having a frequency fs and a phase difference at each 120 degrees. An aural controller 2 inputs a central value fco of frequency of a triangular carrier wave for modu lating a sine wave control signal of frequency fs, and outputs a voltage signal Vf of a frequency varying in a triangular wave state and being an integral multiple of the frequency fs with, the maximum fluctuation width of the signal vf being the difference between a maximum value and a minimum value. Specifications regarding to the frequency varying in a triangular state are so suitably determined as to effectively suppress the electromagnetic sound of a motor. Thus, a harmful motor electromagnetic sound in an audible fre quency band can be reduced. |
