Design of Rectifier Circuit for Wireless Power Transfer to Pipeline Inspection Robots

Inspecting the safety of gas pipelines is essential for our lives. Recently, a novel method of pipeline inspection from inside by robots has been proposed and put to practical use. The robots can run a limited distance depending on their batteries, and the battery life is not long enough for the whole inspections. One of the methods to solve this problem is microwave wireless power transfer(MWPT). MWPT can make the distance longer because the approach eliminates the need of the batteries. We are focusing on the WPT with microwaves and rectifiers used in the receiving units of the new inspecting system. Their rectifiers should be small enough for installing to the inspecting robots. The limitation is a trapezoid, whose upper sides is 1.9 cm, lower side is 5.0 cm, and height is 5.0 cm. We designed a 2.45 GHz single-shunt rectifier with the former condition. The experimental results showed the maximum rf-dc conversion efficiency of 80.6%.