An Approach to Calculate the Efficiency for an N-Receiver Wireless Power Transfer System

Abstract

Abstract-A wireless power transfer system with more than one receiver is a realistic proposition for charging multiple devices such as phones and a tablets. Therefore, it is necessary to consider systems with single transmitters and multiple receivers in terms of efficiency. Current offerings only consider single device charging systems. A problem encountered is the efficiency of one receiver can be affected by another because of the mutual inductance between them. In this paper, an efficiency calculation method is presented for a wireless power transfer system with one to N-receivers. The mutual inductance between coils is implicitly calculated for different spatial positions and verified by practical experimentation. The effect of changing parameters, such as resonant frequency, coil size and distance between coils, on the efficiency has been studied. A clarification of the special performance of a wireless power transfer system at a specific point has been presented.

High Efficiency with Small Coils Area Ratio of Magnetic Resonant Wireless Power Transfer System

“…This can be achieved by applying Kirchhoff's law of voltage on each loop in Fig. 1 in order to express the circuit as following [5]:…”

Using Input Impedance to Calculate the Efficiency Numerically of Series-Parallel Magnetic Resonant Wireless Power Transfer Systems

“…As a near field technology, magnetic resonant wireless power transfer systems can achieve high efficiency in specific conditions. Where the efficiency of the maximum transfer of power is affected by several factors; these are the resonant frequency, the parameters of the coils (inductance, size, and shape), the distance between them and so the mutual inductance, the load resistor, and the connection type of the transmitter and the receiver [1], [2]. To improve the performance of the wireless system, it is important to calculate the efficiency and understand how it is affected by each factor.…”