Transferência indutiva de potência em baixas frequências para alimentação de sistemas subaquáticos isolados

Abstract

This document presents a study on low frequency Inductive Power Transfer (IPT) to supply isolated underwater systems, for instance, Autonomous Underwater Vehicles (AUV). To perform the wireless power transfer between source and load, a Split Core Transformer (SCT) was built. In this way, the batteries of the AUV can be charge during the docking process, with the vehicle in the water. Due to the gap, the output voltage and efficiency of the SCT are compromised. Therefore, to define an operating point where the transformer is able to supply the load with good efficiency, a study on compensation of the parameters of the SCT, based on the choice of the excitation frequency and series and parallel capacitances, is presented. Because of misalignment between the source and the AUV, during the docking process, the parameters of the SCT vary dramatically, changing the coupling factor, output voltage, and system effi-ciency. Therefore, the behavior of the compensated SCT was investigated under gap variations and a strategy to track the maximum efficiency of the SCT, without com-munication between primary and secondary, was developed. To perform these studies and to verify the behavior of the SCT under gap variations, a mathematical model, by means of a parameter determination methodology, was obtained from no load and short circuit tests on the SCT. The power supply of the system is composed to a variable frequency voltage source inverter with sinusoidal output voltage, or with a square wave output voltage. Finally, experimental results demonstrating the operation of the SCT as expected by the mathematical model, as well as the performance of the maximum efficiency tracking strategy, is presented.