| Wireless power transmission is a non-contact power transmission technology.The transmission mode is mainly composed of electromagnetic induction,microwave,laser and magnetic coupling resonance.Among them,magnetically coupled resonant wireless energy transmission technology has the excellent properties of realizing higher power and longer distance transmission.This transmission method has been a hotspot in the research and development of modern electrical technology since its inception.Moreover,this technology is currently the most likely to provide real-time wireless power for portable appliances,implantable medical devices and smart wearable electronic products,an optimal means of flexible access and transmission of electrical energy.Because this technology mainly uses the principle of resonance and magnetic field coupling to transmit electrical energy,the maximum efficiency of wireless energy transmission can be achieved only when the size of the transmission frequency is consistent with the natural frequency when the transmitting and receiving coils generate resonance.Otherwise,the system will be detunedand the overall transmission efficiency of the system will be greatly reduced.How to keep the repetition frequency of the control signal of the transmitting module consistent with the resonant frequency f of the transmitting and receiving coils is the difficulty in designing the WPT transmitting module and the focus of WPT technology application in engineering.Based on the research of the laboratory in recent years,this paper designs a circuit that provides control signals for the power amplifier tube IRF510 grid,and implements a microcomputer-based frequency control system with temperature compensation.The main contents of the study include:Firstly,according to the winding of the transmitting and receiving coil with a resonance frequency of 7.3728 MHz,the function relationship between the transmission frequency and the transmission efficiency of the transmitting and receiving coil and the resonance frequency is obtained.Based on this,the frequency stability of the temperature-compensated crystal oscillator is determined.The resonance frequency of the coil determines the repetition frequency of the power amplifier gate control signal.The gate control signal of the power amplifier is provided by a temperature-compensated crystal oscillator with high stability in this design.Through analysis and comparison,this paper uses a microcomputer temperature compensation method anddesigns the software and hardware of the temperature compensation system.The results show that the stability of the power amplifier gate control signal is controlled within 1 ppm in the temperature range of-10 ℃ to 70 ℃.Under this frequency stability,the transmission efficiency of the transceiver coil is stabilized in the range of 78%-80%. |
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