Power Transfer Networks Research Articles

Green Wireless Power Transfer Networks

A wireless power transfer network (WPTN) aims to support devices with cable-less energy on-demand. Unfortunately, wireless power transfer itself—especially through radio frequency radiation rectification—is fairly inefficient due to decaying power with distance, antenna polarization, etc. Consequently, idle charging needs to be minimized to reduce the already large costs of providing energy to the receivers. In turn, energy saving in a WPTN can be boosted by simply switching off the energy transmitter when the received energy is too weak for rectification. Therefore in this paper we propose, and experimentally evaluate, two “green” protocols for the control plane of static charger/mobile receiver WPTN aimed at optimizing the charger workflow to make the WPTN reduce idle time of transmitters. Those protocols are: “beaconing,” where receivers advertise their presence to the WPTN, and “probing” exploiting the receiver feedback from the WPTN on the level of received energy. We demonstrate that both protocols reduce the unnecessary WPTN uptime, however trading it for the reduced energy provision, compared to the base case of “WPTN charger always on.” For example, our system (in our experiments) saves at most $\approx 80\%$ of energy at the charger with only $\approx 17\%$ less energy possibly harvested.

Wireless information and energy transfer in multi-cluster MIMO uplink networks through opportunistic interference alignment

In this paper, we consider a $K$ -cluster $\left ({K\geq 2}\right )$ simultaneous wireless information and power transfer network, where $S$ nodes $\left ({S\geq 2}\right )$ are selected from $N$ nodes within each cluster for the uplink information transmission and the remaining $N-S$ idle nodes are dedicated to energy harvesting. Based on the intra-cluster performance aware (ICPA) philosophy, a pair of opportunistic interference alignment (OIA) schemes, namely, the coarse ICPA-OIA (C-ICPA-OIA) and the refined ICPA-OIA (R-ICPA-OIA), are proposed for balancing the sum rate performance achieved and the energy harvested. Specifically, the C-ICPA-OIA treats the overall signal strength within the reference signal subspace (RSS) as a coarse description of the node’s effective signal strength. By comparison, to take full advantage of zero-forcing-based reception, the R-ICPA-OIA considers the projected signal strength with respect to the orthonormal basis of RSS as a substantially refined description of the node’s effective signal strength. Furthermore, we analyzed the harvested power and the working time of the system. Extensive simulation results validate our theoretical analyses, demonstrating that our schemes outperform the existing OIA schemes.

Design and study of multi-dimensional wireless power transfer transmission systems and architectures

This paper reports on the design of multidimensional wireless power distribution using cellular concept, Helmholtz coils and cubical node design with power transmission capability over a distance of 6m. To provide strong and uniform power delivery along the power transfer link axis, pairs of Helmholtz coils which are capable of creating uniform magnetic fields are used. To distribute wireless power in multiple dimensions the transmitter containing six secondary coils and one primary coil were used. The secondary coils orient magnetic files in six directions and the primary coil provides power transfer in the vertical direction. A cellular concept which permits the planning of power transfer over wide area is proposed. Furthermore, we have used a class E power source to power the transmitter. Class E power amplifiers provide stable resonant outputs to which the transmitter responds in sympathy. They also provide high voltage outputs and low currents making them safe for high voltage operations. The proposed cellular architecture with the multidimensional transmitter and receivers are demonstrated to be an excellent choice for inductive wireless power distribution over long distances. The multidimensional transmitter behaves like an inductive power coupler. With only one multidimensional transmitter and receivers, a range of about 6m has been achieved end to end. The cellular architecture allows the power transfer network to be planned. Further range extension can be achieved by using a relay coil placed 9cm above the primary coil.

Estimation of Transferred Power from a Noise Source to an IC with Forwarded Power Characteristics

This paper proposes an accurate approach for predicting transferred power from a noise source to integrated circuits based on the characteristics of the power transfer network. A power delivery trace on a package and a printed circuit board are designed to transmit power from an external source to integrated circuits. The power is demonstrated between an injection terminal on the edge of the printed circuit board and integrated circuits, and the power transfer function of the power distribution network is derived. A two-tier calibration is applied to the test, and scattering parameters of the network are measured for the calculation of the power transfer function. After testing to obtain the indispensable parameters, the real received and tolerable power of the integrated circuits can be easily achieved. Our proposed estimation method is an enhancement of the existing the International Electrotechnical Commission standard for precise prediction of the electromagnetic immunity of integrated circuits.

A CLASS E POWER AMPLIFIER WITH COUPLING COILS FOR A WIRELESS POWER TRANSFER SYSTEM

A class E power amplifler including coupling coils is proposed for application in a wireless power transfer system using magnetic coupling. The proposed amplifler is directly connected to the coils with no discrete components for harmonic flltering and dc feeding, which could cause e-ciency degradation of the amplifler. The system with the difierential amplifler shows 6.95W of transmitted power and 44.6% transmission e-ciency at 6.8MHz with 14-cm distant coils. The power-added e-ciency of the amplifler is 92.1% with a 14V supply voltage, excluding the coupling e-ciency of the wireless power transfer network.