Optimized Design Of Asymmetric Coupling Mechanism In WPT System

High-speed railway train is a kind of special super-large power load in the power grid,which has five characteristics such as high safety,high smoothness,high stability,high reliability and high accuracy.To ensure the realization of the above characteristics,the key is to deal with the relationship between pantograph and catenary.With the increasing speed of high-speed railway,the way of electric power obtained by sliding contact which makes the relationship of high-speed bow network becoming complicated and changeable.This phenomenon has restricted the development of high-speed railway seriously.Wireless Power Transfer technology,as a new power supply technology,provides wireless power supply for locomotives high-efficiency and large-capacity.This way of power supply can avoid material wear between pantograph and catenary wire,arc and others.In addition,it has a very attractive application prospect.Induction power transfer technology is the best way to realize short distance and high-power transmission,which has gained wide attention in recent years.For the IPT system,the high-quality coupling coil has a direct impact on the transmission efficiency,transmission power and transmission distance of the system.However,in practical applications,due to the limited working space,the coil size cannot be too large,so it is necessary to consider how to reduce the coil size under the condition of ensuring transmission performance.In addition,in order to design high-power and high-efficiency WPT systems suitable for rail transit,the optimization and design of asymmetric coupling coil is an inevitable problem.In order to achieve the goal of powering high-speed electric locomotives by means of WPT technology,the subject analyzes and compares the existing WPT coupling structure by using the general mathematical model of electric energy induction transformation unit when asymmetric coupling.And this subject takes into account the actual working conditions of high-speed movement of electric locomotives,and this actual situation is decomposed into the characteristics of the longitudinal and lateral directions of the asymmetric coupling mechanism at rest.Finally,designing a coil structure maximizes the capacity and efficiency of the WPT system.Firstly,the longitudinal characteristics of the asymmetric coupling mechanism at rest are analyzed.Based on this characteristic,an asymmetric "parallel-series" coil structure is proposed.The structure has a large power density,a small size and a light weight,and it can be well applied to wireless power supply of a tram.Secondly,the thesis analyzes the lateral characteristics of the asymmetric coupling mechanism and a new type of "Tai Chi" coil structure is proposed.The structure solves the serious coupling mechanism deviation phenomenon of the tram,improves the transmission efficiency of the system and enhances the stability of the energy transmission system.The power transfer performance of the new"Tai Chi" structure is verified by theory,simulation and experiment.The results show that the magnetic field distribution characteristics of the proposed structure in the "z" direction are better than the "double D"structure and the traditional planar spiral coil structure.Finally,we can get a conclusion that the Tai Chi has superior anti-offset characteristics.Finally,the subject integrates the design of "parallel-series" coil structure into the "Tai chi" coil structure,and combines the longitudinal and lateral characteristics of the asymmetric coupling mechanism at rest to propose a new structure of "Tai chi and spiral coil".The structure can increase the transmission efficiency in the longitudinal direction as well as improve the lateral anti-offset capability,which provides a powerful reference value for the high-efficient transmission and stable operation of the dynamic tram.