| 摘要 |
PURPOSE:To obtain an inverter unit in which noise of motor is produced as voice by providing a carrier frequency control means performing switching control of carrier frequency according to a predetermined voice pattern with half period as unit. CONSTITUTION:An inverter main circuit 1 is subjected to PWM control based on operational frequency fd and carrier frequency fc and drives a motor 2. A carrier frequency control means 3 comprises a recording means 4 for previously storing carrier frequencies corresponding to a plurality of types of frequency composing voice, and a carrier frequency switching means 6 for switching the carrier frequency through time ratio control according to a voice pattern of frequency component with half frequency as unit and delivering a carrier frequency fc' to the inverter main circuit 1. When the inverter main circuit 1 is subjected to PWM control based on the carrier frequency in order to drive the motor 2, operational noise of the motor 2 is produced as voice thus solving noise problem. |
