| 摘要 |
PURPOSE:To decrease ON/OFF frequency of a semiconductor element by determining carrier under asynchronous mode such that the amplitude of modulated wave has a specific value and the carrier frequency has maximum value then switching the carrier frequency continuously according to the inverter frequency and output voltage thereby suppressing ripple and maximum value of motor current peak. CONSTITUTION:Carrier frequency fCH to be determined under asynchronous mode is increased continuously with increase of inverter frequency fIN in low frequency region thereof so that the modulated wave has a specific value and the carrier frequency fCH has a maximum value. When the carrier frequency fCH is varied continuously according to the inverter frequency fIN, control rage of the inverter frequency fIN under asynchronous mode is increased. By such arrangement, ripple and maximum value of motor current peak can be suppressed, and ON/OFF frequency of semiconductor element can be decreased. |
