Bidirectional Signal Of ICPT System Based On Frequency And Phase Modulation

With years of development, the wireless power transmission (WPT) technology isrelatively mature. Inductively coupled power transfer (ICPT) technology can be definedas a technology where power is transferred in wireless way between two electricalisolated sides by a high-frequency alternating magnetic-field. Since getting rid ofshackles of the power cable, ICPT technology is widely used in household appliances,oil drilling, implantable medical devices，electric vehicle charging and other industries.However, in many cases, the power and signal often require simultaneous transmission,power to provide energy for electrical equipment, and signal transfer controlinstructions and feedback. Currently, the separating transmission technology is alreadyvery mature, but the research on energy and signals share the same transmission channelis also less.The thesis’s background is “electrical power and signal’s coupled transmissiondevice”, which is a school-enterprise cooperation project. On the basis of the research ofICPT, the thesis studies the problem of signal transmission using the energy channel.For transmission of signals from the primary side to the secondary side, the thesispresents a FM modulation method by changing the inverter frequency and thecompensation capacitor of the primary resonant network. This method makes theprimary side to keep working in the resonant state so that the energy loss is reduced, andthe impact on the signal transmission is reduced, too. For transmission of signals fromthe secondary side to the primary side, the thesis presents a phase-modulatedtransmission method through changing the secondary compensation capacitor. Bychanging the secondary compensation capacitor, the phase of the input voltage and theresonant current was changed, so that the signal was loaded. For the signal wascharacterized by phase, the transmission speed was increased. The thesis studies theequivalent model of the primary and secondary windings, analyzed the primary side’samplitude-frequency and phase-frequency characteristics, introduced the transmissionmechanism and signal modulation method, and the demodulating process was alsointroduced.Since the energy and signal is transmitted through the same channel, the signalspeed is limited by the energy frequency. Also the energy transmission will be affectedby the signal transmission. The energy transfer efficiency is with different affect if the quality factor is different. The thesis presents a four switch BUCKBOOST regulator.The circuit will work in BUCK mode, BOOST mode and BUCKBOOST modesrespectively according to the relationship between the input voltage and output voltage.The thesis describes the switch timing of each mode, and presents the efficiency trendsof the converter.