The Design Of A Tracking Microwave Wireless Power Transmission System For Movable Objects

Non-contact power transmission has significant advantages in specific applications,such as distributed sensor networks and RFID.In some scenarios such as high-voltage isolation,dust-free chamber,pressurized chambers,implanted equipment,and rotating or moving targets,wireless power transmission(WPT)is the only option that enables the targets to operate continuously.In the field of WPT,microwave-based WPT(MPT)has attracted much attention due to its relatively long transmission range.At present,most microwave-based wireless power transmission systems cannot track or detect targets,thus their application is limited to powering fixed targets.To break such limitations,the phased array technology is studied to enhance the MPT,with an application-oriented perspective.Using general-purpose devices and modular design schemes,a prototype of the MPT system was built and analyzed,with the capability of target detection and tracking.In this thesis,the technical background,application,and prospect of MPT were explained in detail.This work includes difficulties and solutions when implementing target detection algorithm and phased array control,as well as the testing of the system hardware.The MPT system in this work operates under 2.4 to 2.5 GHz and can track moving targets by detecting the pilot signal sent by targets themselves using the direction-of-arrival(Do A)algorithm,then the power can be supplied to the target purposefully with beamforming.In addition to the electronically controlled beam scanning,the system is also equipped with a mechanical scanning platform.It can further widen the range of target detection and power transmission,which complements the agility of the beamforming.The system transmits power using microwave energy as the medium and can detect the pilot signals sent by the targets in a time-divided manner.The aggregated data is then transferred through the USB interface to the computer for software processing to estimate the Do A.The beamforming and scanning platform movement command is then issued to point the power beam to the target.The system was designed in a layered structure.It consists of 6×6 active antenna units.With experimental verification,the system has a power output capability of up to180 W and can track and transmit power to targets at a relatively high speed.Using the calibration and MUSIC algorithm,the detected target angle error is less than 4°,and it can stably track moving targets with movement speed of no more than 25 cm/s at 3 m distance,through mechanical and electronic steering.This system can perform stable power transmission for such targets,and the expected design goals of tracking and powering moving targets were achieved.