Research On Key Issues Of Sectional Track-based Wireless Power Supply Technology For Electric Vehicles

The green electric vehicles have aroused public attentions because of fossil fuelshortage and environmental deterioration. However, problems exist in the conductioncharging mode, which is used intensively by current electric vehicles, such as, Highcharging current, especially in quick charge mode; Heavy connector, affectting thebeauty of environment; Complicated operation, parking, connectingelectric vehiclecable with charger cable are needed before charging; Poor contact, electric spark willappear when using for a long time because of mechanical friction between socket andplug; Leakage accident may be caused by wire aging, bad weather, forget to removeconnector or pull to cables carelessly. In addition, immature battery technology has alsohindered the develepment and promotion of electric vehicles. It makes the electricvehicles exist some drawbacks, such as, large battery space, short mileage, longcharging time, frequent charging.In the electromagnetic induction-based wireless dynamic power supply system forelectric vehicles, electrical energy can be transmited wirelessly from underground trackor coil array to the vehicle-mounted battery pack or electric motor, which is a real-timepower supply from road to electric vehicles. With the help of such system, storagebattery in electric vehicles can be cutted down even be canceled, and the mileage will beextended, and the power supply will be more convenient and security.The power track may be needed as long as several kilometers even dozens ofkilometers for the enough power supply to electric vehicles in dynamic wireless powersupply system. Research and optimization design of track can make this system morestabilized, efficient and economic. And this is an urgent issue to the development ofwireless power supply technology for electric vehicles. Moreover, the load is dynamicand random obviously, and relative position between pick-up winding and energy trackis uncertain, so coupling parameter is constantly changing, which will lead to unstableoutput power. This is another urgent issue to be investigated and solved.This paper studies on the energy track mode and its optimization design and theoutput power control. Several relevant supported technology and theory of dynamicwireless power supply system for electric vehicles have been analyzed and researched.Based on the research in energy track mode, a new sectional track mode named as highfrequency and high voltage distribution-low voltage and constant current exciting mode has been presented. The power-efficiency character and nonlinear behavior of systembased on a circuit topology, which is suitable for the proposed track mode have beenstudied. A nonlinear programming mathematical model of sectional energy track hasbeen built on and an improved particle swarm optimization algorithm was adoptted toanalyze the proposed mathematical model. Morever, a neural network-based outputpower control strategy has been presented and a BP neural network controller wasdesigned.This paper has the following main innovative contributions:1. As the problem of low transmission efficiency and parameter sensitivity ofcentralized power supply track, a novel sectional track mode named as high frequencyand high voltage distribution-low voltage and constant current exciting mode has beenproposed. Being suitable to the proposed track mode, an electricity-transformationtopology with its nonlineaer behavior was studied, which provides a theoreticalfoundation for the system paramter designing.2. As the problem of power switching and tracks planning in sectional track mode,a swtitching strategy and its realization based on magnetic field approximation has beenproposed. It improves the stationarity of output power when two contiguous tracksswitching for power supply, which can lower the requirement of power regulator.Moreover, a nonlinear programming mathematical model of sectional power supplytrack has been proposed. An improved particle swarm optimization algorithm wasadoptted to analyze the proposed mathematical model to minimize the operation cost ofsystem.3. As the relative position between pick-up winding and energy track is randomand uncertain, so the coupling parameter is constantly changing, whick leads to outputpower unstable. To this problem, an output power control strategy based on neuralnetwork is presented, which makes output power be regulated quickly and accurately.