| Wireless power transmission technology is proposed to make the electrical equipment work without the wire,solving problems on the lacking flexibility of movement and the electric spark while contacting each other,ensuring the safety and reliability of the system under the harsh environment.At present the studies on wireless power transmission technology are mostly in the air environment inland,underwater environment wireless charging research is still relatively scarce.The power of underwater electromechanical equipment is usually supplied by the cable.The joint may be caused hidden dangers by the wear and tear while the wet plug connected in the water.As a consequence,if the wireless power transmission technology is applied to the power supply of the underwater equipment by non contact energy transmission,the above problem can be avoided effectively.In this paper,the key technologies of wireless energy transmission system for underwater applications will be mainly studied.First and foremost,according to the different electrical conductivity of seawater,from the characteristics of underwater electromagnetic wave transmission research,the working frequency range is proposed for underwater wireless energy transmission system.A wireless power transmission system is designed for underwater application based on this kind of working frequency.The mutual inductance model of loosely coupled transformer is established.Considered the impact of sea water,a wireless energy transmission system modeling method which is suitable for underwater environment is put forward,the differences between the improved model and the original model is analyzed.In addition,aim at the transmission characteristics of the resonant compensation network,a kind of parameters adjustment method of resonant compensation network under different targets is proposed.Through analysis of transmission characteristics of different compensation structures,the PSSS and PSSP compensation structures are selected which have better properties to accomplish system parameters integrated design.It will lay the foundation of systematic design to achieve the high power,high efficiency and stability working characteristics.In view of the issues on traditional analysis of complex and without the universality,a generalized compensation of a loosely coupled transformer for dual port network unified modeling method is proposed.In view of the unilateral and bilateral compensation network structures establish unified output power and transmission efficiency model,simplifying the analysis process based on the foundation of ensuring the calculation accuracy.What's more,aim at the influence of frequency bifurcation,load sudden change and load impedance mismatch phenomenon on system stability,a classification parameter adjustment method is proposed to achieve system stability optimization design,which optimized from the system stability,output voltage stability and load matching three aspects.The method makes the system output power maximization and transmission efficiency optimal performance into reality under the premise of satisfying the stability.Furthermore,according to the performance index of the system,a complete set of wireless energy transmission experiment platform and the main circuit components of the system are designed.Considering all kinds of factors that influence the loosely coupled transformer,a multiple parameters simulation analysis method of electromagnetic field is presented,which comprehensive analyzes the impacts of core,coil,gap spacing,the surrounding medium and the external circuit parameters on magnetic field distribution,and then to optimize the design of loosely coupled transformer.By the circuit simulation,the rationality of systematic design is verified and the influences of load changing on different compensation system are shown.Last but not least,an integration wireless power transmission system experimental platform is accomplished.In air medium the system function realization,the system applicability under horizontal shift,the loosely coupled transformer optimization performance and the outside circuit parameters influence on the system performance are verified respectively.Complete system transmission performance testing in three different mediums air,fresh water and seawater.The designed system under a certain air gap spacing or horizontal offset situation can still achieve high transmission efficiency.This means that the designed system is applicability under the influence of the underwater environment interference(e.g.ocean current)or the position and attitude control deviation on wireless power transmission system. |
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