A Dual-frequency Multi-load Wireless Charging System Based On Helmholtz Coil

With the continuous update and iteration of electronic products and the continuous diversification of functions,the power supply mode of the equipment is constantly pursuing high efficiency and high reliability.Compared with traditional wire transmission,wireless power transfer(Wireless Power Transfer,WPT)has the advantages of being safe,reliable,convenient and fast,making it one of the hot topics discussed by researchers today.Multi-frequency and multi-load magnetic coupling resonance wireless power transfer technology can simultaneously supply power to multiple devices with different frequency standards,and has the advantages of wide adaptability to miniaturized charging equipment and high frequency utilization.The power supply platform proposed in this paper is suitable for wireless charging applications of miniaturized electronic devices such as mobile phones and tablets.The main contents of this article are:(1)Taking a dual-frequency multi-load wireless power transfer system as an example,a voltage source with two different operating frequencies,a repeater composed of a Helmholtz coil and a frequency selection CLC network,and multiple operating frequencies are proposed.A wireless charging system composed of receiving coils of different frequencies and load resistance.The relative position of the two transmitting coils is carefully arranged to eliminate the coupling between the transmitting ends;the relay end coil adopts the Helmholtz coil structure to generate a uniform magnetic field that can cover a certain three-dimensional space,and the relay end adopts a CLC compensation network to obtain double Frequency selection function;at the receiving end,in order to suppress inter-frequency interference,a bandpass-bandstop compensation network composed of LC devices is used.Simulations and experiments show that the system has good voltage load-independent characteristics,and has a strong inhibitory effect on inter-frequency interference.With good cross-frequency isolation performance,high system efficiency,single-frequency or dual-frequency operation,load-independent constant voltage output,the system can be easily used in various small and medium power multi-load wireless charging applications or wireless charging applications that require dual-frequency operation Information-electric energy coordinated transmission application.(2)A dual-frequency multi-load wireless charging experiment system based on Helmholtz coils was built,and the two groups of working frequencies were 60 k Hz and 100 k Hz.Performance parameters such as load voltage and system efficiency were tested under the conditions of a single frequency source working and two frequency sources working together.The experimental results are consistent with the theory.Theoretical analysis and experiments prove that when two voltage sources of different frequencies are supplied at the same time,the inter-frequency interference of the receiving end of different operating frequencies is effectively suppressed.