The Study Of The System Performance Of The Magnetically Coupled Resonant Wireless Power Transmission In The Non-resonant Status

According to the comparison between the magnetically coupled resonant wireless power transmission system and electromagnetic radiation wireless power transmission system, the former has a higher efficiency for output. Moreover, the former system can achieve a longer distance of transmission than the inductive wireless power transmission system. Hence, the magnetically coupled resonant wireless power transmission system has been applied more widely. However, it is also faced with the tricky problem of the resonance frequency detuning. Based on the theory and model of the coupled resonant wireless power transmission, this paper will analyze the mechanism of the detuning. After discussing various factors influencing the detuning in the system, it will also offer some methods to detect the detuning and improve the system efficiency accordingly. This paper will also make a mathematical description for the model and conduct the qualitative analysis on various factors causing the detuning. Moreover, it has come to the conclusion that those factors will have an effect on the power and efficiency of the transmission. This paper has also designed the frequency tracking method so as to improve the system efficiency in the event of detuning.Firstly, this paper has made a study of the transmission performance of the system. By building a model for the RWPT equivalent circuit as well as combining the theoretical analysis with the simulation verification, this paper has gained the detuning mechanism. The precondition for the receiving coil absorbing most energy of the transmitting coil is that the frequency of radiating circuit should be equal to the natural frequency of the receiving circuit. Because of the minimal matching impedance at this point, it will lead to the maximum current, thus making the receiving coil absorb the majority of the transmitting coil. Otherwise, if their frequency is not consistent with each other, it will lead to the detuning, which means that the transmitting circuit will consume most energy in the transmitter. Hence, the energy will not be absorbed by the circuit and thus reduce the efficiency for output. In a word, the key to realizing the magnetically coupled resonant wireless power transmission is to make the frequency of the transmitter equal to the natural resonant frequency of the system.This paper will also offer some countermeasures to tackle the RWPT frequency detuning. It will involve the RWPT frequency tracking control. If the topology takes the form of SS or SP, the current signal of the transmitting coil will be tracked by the frequency directly. However, the phase-shift processing should be required in order to track the frequency of current signal in the receiving coil. According to the experimental results, the system has the function of automatic adjustment. Even if the system frequency is not eligible at the beginning, it can still automatically adjust the frequency to the standard value so as to track the frequency of the transmitting signal during the process of operation. In the case of different transmission distances, the system without the function of frequency tracking has been far outperformed by the system that can track the frequency of the current signal in the transmitting coil.Based on the analysis and research above, the controller that generates the driving pulse signal should be FPGA and DSP. The hardware can be also designed for the frequency tracking control. A wireless power transmission system has been designed and realized accordingly.