IEEE 2017-2018 Project Titles on Wireless Power Transfer
Abstract:This paper investigates the optimal energy beamforming and time assignment in radio frequency (RF) energy harvesting (EH) wireless powered sensor networks for smart cities, where sensor nodes (SNs) first harvest energy from a sink node, and then transmit their collected data to the sink node via time-division-multiple-access (TDMA) manner by using the harvested energy. In order to achieve green system design, we formulate a problem to minimize the energy requirement of the sink node to support transmission between the sink node and the SNs under data amount constraint and EH constraint. For practical design, the energy consumed by circuit and information processing is also considered. Since the problem is non-convex, we use semidefinite relaxation (SDR) method to relax it into a convex optimization problem and then solve it efficiently. We theoretically prove that when the number of SNs are not greater than two, the relaxed problem guarantees rank-one constraint and when the number of SNs exceeds two, our obtained results are very close to the optimal ones. Simulation results show that when the data amount is relatively small, the energy consumed by circuit and information processing affects the system performance greatly, but for a relatively large data amount, the energy requirement of the sink node on its own signal processing is affected very limited and the system energy requirement is dominated by the transmit power consumption at the SNs. Furthermore, we also discuss the effects of the other parameters on the system performance, which provide some useful insights in future smart city planning.
Abstract:As the power demand for some railway applications rises up to the Megawatt level, the conventional Wireless Power Transfer (WPT) system can hardly meet the power requirements for rail vehicles due to capacity constraints of power electronic devices. In order to improve the power capacity of the WPT system, a novel dual transmitters and dual receivers based WPT system is proposed. The dual transmitters are totally overlapped and located close to each other to enhance the magnetic field, which results in a non-negligible mutual crossing coupling between the transmitters. Besides, the dual receivers are located to capture the magnetic field simultaneously, and the cross coupling between the receivers is also non-negligible. The effects of the mutual crossings between the transmitters and that between the receivers are analyzed. It shows that the cross couplings will decrease the efficiency and transmitted power. Decoupling transformers (DTs) are employed to mitigate the effects of the cross couplings. Finally, a low scale experimental setup is provided to verify the proposed approach. The experimental results indicate that the proposed method could improve the transmitted power and overall efficiency, simultaneously.
Abstract:This paper addresses the recent advances obtained in LAAS-CNRS Toulouse concerning the development of compact, high-efficiency and multiband RF/microwave energy harvesting devices for autonomous wireless sensors. Several topology of rectenna designed for the Structural Health Monitoring of the satellite antenna panels and for Internet of Things application are discussed.
Abstract:This paper deals with an active load impedance design to enhance adaptive reconfigurable rectifier performance. The proposed design aim is to address issues raised by early breakdown voltage effect in conventional rectifiers and extends the rectifier operation for wider input power range. The active load, introduced to actively modulate and operate as switch for various terminations at both low and high RF input power levels, achieves 40% of RF-DC power conversion efficiency over a wide dynamic range of input power from -17 dBm to 32 dBm, while exhibiting 80% of peak power efficiency at 12 dBm. The active load power harvester was designed to operate in the 915 MHz ISM band and suitable for Wireless Power Transfer applications.
Abstract:Electric vehicles (EVs) will become a component of the future generation intelligent transportation system. Because of EVs' limited battery power, the wireless power transfer (WPT) system has drawn much attention in recent years. The WPT system charges EVs in motion when they pass the charging lanes installed in roads without requiring physical contact between utility power supply and vehicle battery. A charging lane has limited power that can be transferred to EVs on the charging lane. A challenge here is how to allocate the limited power to the EVs so that they have sufficient power to arrive at the next charging lane or their destinations (when there are no charging lanes ahead). In this paper, we study this power distribution scheduling problem. We provide solutions to handle this challenge and also achieve each of the following goals as much as possible: i) balancing the state of charge (SOC) of the EVs, ii) balancing the amount of stored power of the EVs, and iii) minimizing the total power charged. This paper is the first work that handles such a power distribution scheduling problem in WPT systems. Our extensive experiments on MatLab and Simulation for Urban MObility (SUMO) show the effectiveness of our scheduling solutions in achieving the different goals compared with other scheduling methods including first-come-first-serve and equal share.
Abstract:This letter proposes a two-plate capacitive wireless power transfer (CPT) system for electric vehicle charging applications. The vehicle chassis and the earth ground are used to transfer power, which can replace two plates in a conventional four-plate CPT system. Therefore, only two external plates are required in the proposed CPT system. The coupling capacitance between the plates allows the current to flow forward to the vehicle side, and the stray capacitance between the chassis and the earth ground provides the current-returning path. After analyzing the working principle of a CPT system, it shows that the voltage on the vehicle chassis can be reduced through switching frequency, the coupler structure design, and the compensation circuit design. Then, a downsized prototype is implemented to validate the proposed system, in which two inductors are used to compensate the capacitive coupler. Experimental results show that the prototype achieves 350W power transfer with 70% dc-dc efficiency over an air-gap distance of 110 mm, and the RMS voltage on vehicle chassis is limited to 132V.
Abstract:In this paper, we present an impedance matching technique in magnetic-coupling-resonance wireless power transfer system for small implantable medical devices. By developing an equivalent circuit model of the WPT system, we show that impedance matching can be realized. Electromagnetic field simulations demonstrated that our proposed technique has capability of achieving maximum input power and available efficiency without using impedance matching circuits.
Abstract:Achieving wireless power transfer through airborne acoustic/ultrasonic waves has been previously shown to be a feasible alternative when the charging distance is above several times the transducer size. In order to further increase the receiver efficiency, constructing the receiver out of an array of transducer elements to increase the receiver effective area is desirable. In this work, a study on the power combining through series or parallel interconnections of the receiver elements is done to understand the benefits of both cases and the conditions required to maximize receiver efficiency, with measurements and modeling results presented. With a seven element receiver array, a factor of 4.25 increase in receiver efficiency was achieved compared to only using the receiver center transducer.
Abstract:The capability of bi-directional, underwater power transfer (both sending and receiving power) increases the functionality of underwater vehicles by allowing them to be charged and provide charge wirelessly to other systems without leaving the water. To minimize the footprint of the charging circuitry, a single transistor-based full-bridge circuit can be used to either send or receive power. This work focuses on the operation of the circuit in power receive mode, as an active rectifier. An algorithm common for active rectification is presented, and the effects of non-idealities on the timing control and efficiency is presented through experimental results.
Abstract:Unmanned and autonomous systems are used extensively for Navy missions. While most of these systems are able to operate without human interaction, limitations in power capacity place a fundamental limit on overall system autonomy. Inductive wireless power transfer provides an effective way to enhance unmanned systems (vehicles, sensors, etc.). This report examines different methods for efficiently controlling power modulation and determining which side, transmitter or receiver, commands power needs. The need for charging a wide array of systems and bidirectional power capabilities are considered, which point toward a need of underwater wireless power standards, a framework of which is proposed.