Research On ECPST System Based On Differential And Common Mode Separated Circuit

At present,wireless sensor networks(WSNs)technology is widely used in various occasions.Because a large number of sensor nodes are scattered and work in different states,the traditional battery-powered method cannot continue to supply power to the sensor nodes.In this paper,electric-field coupled power transfer(ECPT)technology is used to supply power to the sensor nodes.In addition,closed-loop control needs to be implemented in some places with high reliability requirements of power supply.Therefore,synchronous transmission of power and signal is needed in some applications.This paper proposes an electric-field coupled power and signal transfer(ECPST)system to provide power for wireless sensor network nodes and transmit signals at the same time.In this dissertation,the background and development status of ECPST technology is studied.It is proposed the ECPST system structure based on common mode differential mode separation technology and introduced the working principle of the system in detail.The system performance index is given modeling circuit under different working conditions of the system.The working effect of not interfering with each other when the power and signal are transmitted at the same time under the shared channel is realized through reasonable parameter design.Considering the stability of the system,the impact of parameter changes on the transmission performance of the system is clarified.In order to improve the practicability of the system,simplify the ECPST circuit model and verify the transmission performance of this simplified system through simulation and experiment.Then the hardware circuits of converter in power channel and modulation and demodulation part in signal channel are designed.Using a single-switch DC-DC converter as the power channel converter of the ECPST system,analyz the working process of the system under different modes and derive the voltage and current formulas of components in each working mode.Design parameter selection principles and verify the effect of system through simulation and experiment.Frequency modulation and frequency discrimination method demodulation are adopted for signal transmission.In AD module of DSP chip,the signal to be transmitted is sampled to control the signal source frequency.Design the zero-crossing comparison circuit and the ECAP module of DSP chip to capture the received signal for demodulation.Finally,the feasibility of the scheme is verified by simulation and experiment.An ECPST system was built for experimental verification in the last.The load voltage on the receiving side of the power channel which meets all the power supply requirements of the transmitting side of the signal channel is used as the signal to be transmitted.Finally,the transmission voltage gain of power channel is 0.894 and the demodulation deviation rate of signal channel is 0.0063.At the same time,the transmission voltage gain of power channel changes from 0.3 to 1.7 and the demodulation deviation rate of signal channel changes from0.0025 to 0.007 when system parameters change.