In a power converter, a deviation calculator calculates, in each cycle, a deviation between a value of an input electrical parameter of a switch circuit and a target value selected by a selector in a previous cycle. The cover includes a track and a rotating portion next to the track. A part of the resin casing is disposed in the hollow portion. Thus, resources of each network entity in a network are fully utilized. The system also includes a handpiece attached to the waveguide, wherein the handpiece allows an operator to control the orientation of the output end to direct the radiation to a target location of a patient and the handpiece includes a tip extending past the output end that provides a minimum standoff distance between the output end and the target location.