Patent ID: 7672148

Claim:
A controller of a power converter that converts input electric power into a desired form and outputs the converted electric power by controlling a power converter switch, the controller comprising: a carrier signal generator operable to produce a carrier signal for controlling the power converter switch in accordance with a waveform that periodically changes within a first frequency range from a frequency fc 1 to a frequency fc 2 , wherein the frequency fc 1 is smaller than the frequency fc 2 , and within a second frequency range from a frequency fc 3 to a frequency fc 4 , wherein the frequency fc 3 is smaller than the frequency fc 4 ; and a waveform generator operable to change a frequency of the waveform wherein the frequencies fc 1 and fc 4 satisfy at least one of: (A) an inequality (n−1)·fc 4 ≦n·fc 2 and an inequality n·fc 3 ≦(n+1)·fc 1 with respect to an integer n; and (B) an approximate expression n·fc 4 ≈(n+1)·fc 1 with respect to the integer n; and wherein the frequencies fc 2 and fc 3 satisfy an inequality n·fc 2 ≦fs−Δfs and an inequality fs+Δfs≦n·fc 3 wherein fs±Δfs represents a predetermined frequency band.