The present disclosure provides a power frequency current converter, including: an input side and an output side, wherein a current of the input side or the output side is a power frequency current; a switching device; and a controller, configured to control the switching device to be turned on and turned off at an operating frequency, wherein within a half of a power frequency cycle, the controller generates at least two fixed-frequency control signals and the operating frequency of the switching device alters at least twice according to the at least two fixed-frequency control signals, so as to reduce junction temperature of the switching device.