Study On Cascaded Magnetic Resonance Wireless Power Supply System Drived Low-power Devices

It is always an attractive idea to supply power wirelessly for those low-power devices,which are widespread and relatively concentrated in household and office area.For this reason,a cascade magnetic resonance wireless power system is proposed in household and office area power supply for low-power devices,which can be divided into source-network-load multiple parts,namely high frequency AC source,multi-coil transmission network and multi-load.Due to the equivalent load of low-power devices changes easily,when one of load changes,the power supply characteristics of remaining load will be affected greatly.Therefore,the decoupling design of transmission network is the focus of this paper,including decoupling design of high frequency AC source and transmission network,and decoupling design between transmission networks.The main contents and research results are as follows:First of all,in order to meet the high frequency AC source with high frequency and efficiency,Class E amplifier is chosen.Aiming at the problem that output voltage of Class E amplifier varies greatly with load,this paper presents a design method to realize the wide load variation and constant output voltage characteristics of Class E amplifier.The improved Class E amplifier is derived through equivalent transformation of Class E amplifier and introduction of second harmonic filter circuit,which realized wide load constant voltage operating characteristics and achieved its decoupling design with transmission network.The study of improved Class E amplifier provides a reference for the design of high frequency AC sources.Secondly,owing to some low-power devices in household and office areas have the power supply property of constant-current or constant-voltage,this paper proposes a design strategy of constant-current or constant-voltage power supply by composited passive compensation network.First the transmission characteristics of coil with basic compensation are discussed.And beginning with series-series compensation structure,a composited passive compensation network is introduced at transmission coil or receiving coil side.Then output impedance of wireless power system is designed to realize constant output characteristic of load side.Furthermore,the influence of composited compensation network location and coil parasitic resistance on transmission efficiency and constant power supply characteristics is analyzed.And the parasitic resistances of transmitting coil and receiving coil have different effects on transmission efficiency and constant output characteristic,thereby an asymmetric coil structure is used to improve transmission efficiency and constant output characteristic.This section proposes a design method of constant current or constant voltage,which provide theoretical reference for practical applications of engineering.In addition,this paper presents a cascade wireless power supply scheme to realize wireless power supply of low-power devices in household and office area.To reduce the inter-stage correlation of transmission network,the same scheme is adopted,which uses composited passive compensation network to meet constant current or constant voltage output and achieves transmission network inter-stage decoupling design.Then an application to LED lighting through simulation and experiment verifies its feasibility.The cascade wireless power supply scheme proposed in this section provides a theoretical and engineering reference for wireless power supply design of regional low-power devices.