| Mechanical equipment will meet many kinds of faults in the working process. For continuous working equipment, embedded sensor is needed to monitor the working place where would break down probably. It is required to be solved that supplying energy to embedded sensor at the rotating machine. There are many limits and inconveniences exist in traditional battery or the other power supply methods. Electromagnetic resonant coupling wireless power transmission overcomes weaknesses in the traditional power supply, which can transmit electric energy in moderate range of distance with larger power. In this paper, electromagnetic resonant coupling wireless power transmission is introduced to the power supply of rotating machine fault diagnosis system sensors. We did a lot of work to research this technology and reached some conclusions:1. Introduce theory and characteristics and research situation of domestic and overseas three kinds of wireless power supplying technology (Microwave wireless power transmission and Electromagnetic inductive wireless power transmission and Electromagnetic resonant coupling wireless power transmission). Microwave wireless power transmission can achieve long transmission distance, but it is influenced by barrier seriously with low efficiency. Electromagnetic inductive wireless power transmission can achieve large transmission power but the distance is short. However, electromagnetic resonant coupling wireless power transmission overcome the shortages of two former methods successfully with the characteristics of high efficiency and long transmission distance. According to the characteristics of the power supply of rotating machine fault diagnosis system, we select electromagnetic resonant coupling wireless power transmission for main research.2. Expound the electromagnetic resonant coupling wireless power transmission system at the angle of physics. Electromagnetic field is divided into near-field region and far-field region, and their characteristics are analyzed respectively. We reach a conclusion that the system mainly work in range of near-field region. We analyze the coupling of current-carrying coil and theory of resonance circuit. In order to analyze energy state, we research transmission loss, power, efficiency and transmission mechanism via coupling model theory. Finally, we simple the system to equivalent circuit model to analyze influence of transmission efficiency by frequency, impedance and distance.3. The structure of electromagnetic resonant coupling wireless power transmission system is expounded detailedly. Firstly, we design the system collectively. The system is composed of DC power, signal producing circuit, high-frequency power amplification circuit, transmitting terminal resonance circuit, receiving terminal resonance circuit, static var compensator, load. Secondly, we research various theory of signal producing circuit and high-frequency power amplification circuit, with some designing work. We design two class broadband linear amplifier. Besides, we analyze self-inductance, mutual-inductance, capacitance of coil. And on this basis, we make coil matched capacitance to constitute resonance circuit. At the same time we design static var compensator and select load. Finally, a wireless power transmission platform is built on the basis of module design, achieving7.5W power transmitting at a distance of20cm with62%efficiency.4. We do some finite element analysis on coupling magnetic field of electromagnetic resonant coupling wireless power transmission system. Firstly, we analyze influences on one coil magnetic field by different drive signals and coil parameters, reaching the conclusion that aggrandizing voltage, radius of coil, number of turns can strengthen coupling magnetic field. Secondly, we research the influences of radius, number of turns, distance on a pair of coils coupling magnetic field. The intensity of coupling magnetic field decays along with the increase of distance. Besides, increasing radius and turns of coil can strengthen coupling magnetic field at the same distance. Finally, we analyze the influence of distance on3D coil magnetic field. With the increase of distance, magnetic field distributes widely but the strength decays. It supplies theoretical foundation and instruction for experiments by finite element analysis. 5. After achieving electromagnetic resonant coupling wireless power transmission system, we research its transmission characteristic. Experiments show that the efficiency is highest when it occurs to resonance. Besides, increasing voltage, radius, wire diameter, turns, capacitance can improve transmission performance. We also research angular variation influencing transmission performance. On this basis, we design triaxial receiving terminal for experiment. The result shows that triaxial receiving terminal can receive energy from different directions. Finally, penetrability and security experiment or analysis are implemented. We find that the technology has good penetrability on non-metallic materials. |
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