Multiuser Wireless Power Transfer via Magnetic Resonant Coupling: Performance Analysis, Charging Control, and Power Region Characterization

Abstract

Magnetic resonant coupling (MRC) is an efficient method for realizing the near-field wireless power transfer (WPT). Although the MRC enabled WPT (MRC-WPT) with a single pair of transmitter and receiver has been thoroughly studied in the literature, there is limited work on the general setup with multiple transmitters and/or receivers. In this paper, we consider a point-to-multipoint MRC-WPT system with one transmitter delivering wireless power to a set of distributed receivers. We aim to introduce new applications of signal processing and optimization techniques to the performance characterization and optimization in multiuser WPT via MRC. We first derive closedform expressions for the power drawn from the energy source at the transmitter and that delivered to the load at each receiver. We identify a "near-far" fairness issue in multiuser power transmission due to receivers' distancedependent mutual inductance with the transmitter. To tackle this issue, we propose a centralized charging control algorithm to jointly optimize the receivers' load resistance to minimize the total transmitter power drawn while meeting the given power requirement of each individual load. For ease of practical implementation, we also devise a distributed algorithm for the receivers to adjust their load resistance independently in an iterative manner. Last, we characterize the power region that constitutes all the achievable power-tuples of the loads via controlling their adjustable resistance. In particular, we compare the power regions without versus with the time sharing of users' power transmission, where it is shown that time sharing yields a larger power region in general. Extensive simulation results are provided to validate our analysis and corroborate our study on the multiuser MRC-WPT system.

Precise Analysis on Mutual Inductance Variation in Dynamic Wireless Charging of Electric Vehicle

“…Thus, the distance between adjacent transmitters must be selected precisely and accurately [40]. Approaches to transfer power in an efficient manner in magnetic resonant coupling for different configurations of transmitter and receiver coils are shown in the study of [41,42]. In addition, the power transfer efficiency of the DWPT systems depends on the dimensions and shape of the coils, type of the material used and the design of coil shielding [43][44][45].…”

Magnetic MIMO Signal Processing and Optimization for Wireless Power Transfer

“…Next, we apply the technique of power-profile vector [5] to characterize all the boundary points of the power region, where each boundary power tuple corresponds to a Paretooptimal performance trade-off among the RXs. Let P denote the sum-power delivered to all RXs, i.e., P = Q q=1 p rx,q .…”

“…We assume that each RX q can feed back its measured current to the central controller by using existing communication module. One straightforward method to estimate M nq is given in [5], where by switching off all the other TXs and RXs, TX n can estimate M nq with RX q based on the current measured and fed back by RX q. However, this method may not be efficient for estimating the magnetic MIMO channel M, since it requires synchronized on/off operations of all TXs and RXs and also needs at least N Q iterations to estimate all M nq 's.…”

“…In this subsection, we evaluate the performance of magnetic channel estimation. For performance comparison, we use the channel estimation scheme in [5] as a benchmark, where in each training slot, only one pair of TX n and RX q are switched on, and the mutual inductance between this pair of coils is estimated as…”

Design Optimization Method for the Load Impedance to Maximize the Output Power in Dual Transmitting Resonator Wireless Power Transfer System

“…Recently, resonant inductive coupling wireless power transfer (1)- (9) (WPT) is attracting growing attention as a convenient electric power supply method. In literature, there have been proposed a number of applications of resonant inductive coupling WPT to various apparatus, such as laptops (10) , biomedical implants (11)- (14) , and electric vehicles (15)- (19) .…”