Research On Simultaneous Wireless Power And Information Transmission Based On Source Reconstruction

Wireless power transfer technology has advantages in portability and security which determined it is widely applied in consumer electronics,electric vehicles,implantable medical devices and other fields.In many cases,the device requires communication functions as well as power supply so the simultaneous wireless power and signal transmission technology has become a hot topic in recent years.Electromagnetic wave plays the role of the carrier of energy and information respectively in the field of electric power conversion and communication,and electric power conversion and information transmission,if observered in the frequency domain,belong to the narrowband and broadband system respectively,so the key problem of simultaneous wireless information and power transmission technology is how to deal with tradeoff on this contradiction.In this paper,the traditional communication bandwidth is redefined and subdivided into modulation bandwidth,channel bandwidth and demodulation bandwidth for modulation,transmission and demodulation processes in signal transmission.Wireless power and information transmission functions share channel bandwidth to ensure high efficiency transfer of wireless power.Signal demodulation only needs to meet demodulation bandwidth requirements.In this paper,by using the harmonic amplification effect in the reconstructed source,the channel bandwidth and demodulation bandwidth are decoupled,and the influence of wireless signal transmission on the wireless power transfer efficiency is reduced.In this paper,the application of simultaneous wireless power and signal transmission technology in two typical scenarios,near field and far field,is studied in detail.At first the working scenario and principles of the wireless power transmission system is analyzed,and the factors that affect the efficiency of near field wireless power transmission,such as coil parameters,operating frequency,impedance and coupling coefficient,as well as the phenomenon of frequency splitting is emphatically discussed.Secondly it analyzed the complete process of the communication,defined the concept of modulation bandwidth,channel bandwidth and demodulation bandwidth.And this paper pointed out that the signal demodulation only needs to meet the requirements of demodulation bandwidth without the need for channel bandwidth and modulation bandwidth of the same size.Thirdly,the use of harmonic amplification effect to widen demodulation bandwidth is introduced.On this basis,a method to modulate the power signal directly by using FSK modulation strategy at the transmitting side,reconstructing the square wave source at the receiving side,and extracting the harmonic components from the square wave source as new signal carrier for demodulation after passing the band-pass filter is proposed.Finally,based on the above circuit analysis and the proposed modulation and demodulation strategy,real experiment prototypes are built.The near field experiment platform is a 25 W magnetic coupling resonant prototype,and the experiment verifies that the power transfer efficiency under the communication condition only decreases by 2.2% compared with that without communication.In addition,it is verified that when the operating conditions such as input voltage,transmission gap distance,coil position and varying loads,the demodulation module can completely restore the baseband signal.The far field experiment platform is a RF transceiver device composed of a high frequency function generator and a pair of transceiver antennas with 166 MHz central frequency.In the RF transceiver experiment,the adoption of reconstructed source optimizes the collected signal power spectrum from the original bimodal distribution to the unimodal distribution,and the power density within the bandwidth is increased to 2.8 times,which verified that energy harvesting efficiency is improved.