A power conversion apparatus includes a plurality of semiconductor modules and a plurality of bus bars. The priority level is utilized by a client computer system during transmission of the client’s data over a network. An electrical terminal element is electrically connected to a printed-circuit board via lines. It is further programmed to detect a deviation between a first AF ratio feedback coefficient before the integration term is carried out and a second AF ratio feedback coefficient after the integration term is carried out and the coefficient is shifted by the proportional term set by said means for setting the proportional term.