Design And Research Of Inductively Coupled Wireless Charging Platform For Lithium Batteries

The consumption of power is closely related to the development of human society, and has become an indispensable form of energy in people’s daily life today. With the rapid progress of power electronics technology, the transmission, distribution and use of power are also undergoing changes with each passing day. But in general, the delivery of power in worldwide is still using the traditional transmission mode, wire conduction of electrical connection. This makes the sparks, carbon deposits, mechanical wear and so on, to be inevitable. In some special occasions, such as the chemical industry, mines, underwater environment, the electrical arc will enough lead to accidents. In medical field, the artificial heart has successfully implanted. The charging in vitro of organs battery challenges the traditional power transmission, makes wireless transmission technology came into being.This paper gives in-depth study on inductively coupled wireless charging platform for multi-lithium batteries, and also builds a prototype under laboratory conditions for theory verification. This paper analyzes the circuit topology of inductively wireless power transfer system, gives detailed modeling analysis and theoretical derivation about important parts of system circuits, such as separable transformer, the compensation circuit. The separable transformer uses mutual inductance model; analyzes eight kinds of compensation methods in detail; and finally using the SS mode. In this case, the system has constant current source characteristics, and the parasitic resistance of the winding does not affect the compensation capacitor having a most simple form. Tell the relationship between AC equivalent resistance and DC resistance, the optimal design framework of single lithium battery wireless charging platform, the hardware circuit of charge management chip bq2057, as well as the phase-locked loop HEF4046B. Deduce the cause and eliminate condition of frequency bifurcation when using SS compensation. According to the voltage gain characteristic, the voltage stress of LC devices, the current-carrying capacity of the induction coil, calculate the circuit parameters of the system step by step, to give the optimal design. Considering charging circuit includes different states, the paper puts forward the idea of the standard current control method when single-load. The control scheme is simple in principle, has three advantages. Finally, under laboratory conditions, build the prototype to verify the feasibility of this design through measuring experimental parameters. The paper provides system block diagram of the multi-load wireless power transmission, two loads, for example, deduces the relation of the output power of the primary coil with the change of load resistor, when constant voltage in the primary side, constant current respectively. More specifically, for the circuit of lithium battery charging platform system, the control scheme of constant current in the primary side is given, comparing with the maximum transmission power control scheme. The constant current in primary side achieves the decoupling control of the secondary side coil. The primary side uses full-bridge inverter circuit, achieves phase-shift control with UC3875. The full-bridge converter adopts ZVZCS soft-switching technology, and the paper introduces the working principle of the primary circuit under ZVZCS in detail.