Design And Research Of Wireless Power Transfer System Based On Multiple Loads Access

As the need for more convenient methods of charging electrical equipment has grown,wireless power transfer(WPT)technology,a novel power supply mode,has received more and more attention.Unlike traditional power transmission,which is wire-based,WPT technology is not constrained by cables,does not produce electrical sparks,and has high mobility.Due to these advantages,it has become a hot research topic in the field of energy transfer.At present,WPT is generally used to supply power on a one-to-one basis.For example,WPT technology has been applied to electric vehicles,to embedded medical equipment,and to intelligent electronic devices.It is foreseeable that the application of WPT technology will become more and more popular as the technology,and other new power electronics technologies,continue their rapid development.Furthermore,the technology can be expected to be able to charge multiple equipments simultaneously(just like Wi-Fi).In this thesis,the research on WPT based on multiple loads is analyzed as follows:In the first place,the output characteristics of WPT system with different compensation topologies are compared and analyzed,and the effect of inner resistances of coils on output characteristics of each topology is analyzed.Then,taking dynamic wireless EV charging as an example,its compensation topology is designed from the perspective of system safety.The system parameters design process is also proposed.Based on the analysis above,a constant current- constant voltage charging control strategy is designed for multi-load or single load WPT system.Corresponding simulations and experiments are built to verify the effectiveness of the charging strategy.In the second place,a series-series multi-load WPT system is built to analyze the change of load power when the load quantity varies.And a LCC-S topology,which can improve the stability of load power,is proposed.Through theoretical calculation and analysis,the influence of cross coupling between the coils on the stability of load power is obtained.In order to eliminate the influence,a method by compensating compensation capacitor at the secondary side is proposed.At the same time,the value of compensation capacitor is given.On this basis,through the design of optimal load,the system can operate at a maximum efficiency.Finally,a new compensation topology of multi-load WPT system is modeled and analyzed.Then,the concept of effective working area is proposed.If the receivers are placed within the effective working area,the mutual inductances between receivers and transmitter are almost the same.On this basis,to realize the load detection method,which is convenient for system control purposes,reflection impedance theory is applied to detect the quantity of loads by quantifying the effect of each load on the capacitor voltage at the primary side.Finally,the proposed circuit topology and detection method are practically verified in an experimental prototype.