Design, Experiment And Research On An Under Water Contactless Power Transmission System

Due to the limited size and weight, it is impossible to pack enough batteries in an AUV (autonomous underwater vehicle) for long period cruising. By adopting an underwater power transmission system, it would be more convenient to transfer energy from seafloor observation networks to AUVs (autonomous underwater vehicle) and other observation devices.It is traditional to transfer electricity through metallic contact, even for underwater applications. Meanwhile, the novel contactless power transmission (UCLP) systems transfer electricity through the conversion between electrical energy and magnetic energy. As a result, there is no direct metallic contact. Compared with the traditional means of electricity transmission, the novel contactless power transmission systems are much more reliable.The principle of underwater contactless power transmission has been confirmed in previous research. The implementation of an underwater contactless power transmission system counts on the combination of knowledge from magnetism, mechanics and electronics. The target is a compact system with high transmission capability (500 W) over a large magnetic gap (8mm).This thesis focuses on the PCB design and the magnetic-coupler design. The PCB design includes several segments:a high-frequency converter with controlling circuit, an assistant power supplier, a high-frequency compensation & rectifier circuit and a DC-DC module. All the PCBs should be suitable for anti-water chambers. The magnetic-coupler design includes the choice of magnetic material, magnetic cores, enameled wire, and the circles of the coils. With the assistant from Ansoft Maxwell, a precise design was made.This thesis also contains test results, including a bench test and a real-field test. In the laboratory, a lab bench was set up, and the contactless power transmission system was tested. It proved that the UCLP system could supply 48V/500W DC power over 8mm magnetic gap, with system efficiency ranging from 70% to 75%. If a tolerance of voltage ripple is allowed, the DC-DC module can be removed and the system efficiency would increase to 83%-92%In the real-field test, a 20W underwater illumination device was designed. The testr load consisted of the illumination device, an underwater video camera and a contactless signal transmission system. Finally, the real-field test was carried out in Qiandao Lake. At a depth of 10m, approximate 35W electrical power was successfully transferred, and the system efficiency was 85%.