Research On Dynamic Compensation Strategy Of Multi-load Wireless Power Transfer System

Wireless power transfer system has attracted the attention of scholars for its convenience,flexibility,security and reliability.With the wide use of low-power and medium-power wireless charging products,it is urgent to establish a unified wireless charging platform.At present,the wireless power transfer technology for charging multiple types of devices is still in the initial stage.The multi-load wireless power transfer system based on “single-to-multiple”coupling coil has the advantages of small size,light weight,low cost and good user experience.However,the multilateral coupling characteristics of the coil makes the system more difficult to control,especially when the load changes or the relative position of the primary and secondary coils changes.When these parameter changes,the compensation for the primary circuit may fail,and the system will suffer from reactive power loss,resulting in the decline of the overall efficiency.Therefore,it is necessary to study the characteristics of the multi-load power transfer system under the condition of variable parameters,and propose appropriate control strategies for dynamic compensation,so as to maintain high efficiency and high transmission capacity of the system.This dissertation establishes a unified circuit model of a multi-load wireless power transfer system and finds that when the load changes or the relative position of the primary and secondary coils changes,the capacitive reactance introduced in the primary equivalent circuit changes accordingly,causing the system to generate reactive circulating currents.In order to eliminate the reactive power circulation of the system and improve the transfer efficiency,it is necessary to track the changes of the load and the coupling coefficient and dynamically compensate the system.The fundamental components of the primary voltage and current are extracted by Goertzel algorithm,and the prediction of mutual inductance value can be achieved according to the relationship between the input impedance and the multilateral mutual inductance.In order to eliminate the influence of the capacitive impedance,the switch-controlled capacitor is introduced.Under the condition of variable parameters,the equivalent capacitance of the switch-controlled capacitor is changed according to the prediction results of multilateral mutual inductance,so as to realize the dynamic compensation for the system.Finally,the parameters and hardware and software circuits of the multi-load wireless power transmission system are designed.PSIM software is used for simulation,and a multi-load wireless power transfer system experimental platform is built for experimental verification.Both the simulation and experimental results confirm the accuracy of the multilateral mutual inductance prediction and the efficiency optimization of the system.