Optimal Analytical Solution for a Capacitive Wireless Power Transfer System with One Transmitter and Two Receivers

Abstract

Wireless power transfer from one transmitter to multiple receivers through inductive coupling is slowly entering the market. However, for certain applications, capacitive wireless power transfer (CWPT) using electric coupling might be preferable. In this work, we determine closed-form expressions for a CWPT system with one transmitter and two receivers. We determine the optimal solution for two design requirements: (i) maximum power transfer, and (ii) maximum system efficiency. We derive the optimal loads and provide the analytical expressions for the efficiency and power. We show that the optimal load conductances for the maximum power configuration are always larger than for the maximum efficiency configuration. Furthermore, it is demonstrated that if the receivers are coupled, this can be compensated for by introducing susceptances that have the same value for both configurations. Finally, we numerically verify our results. We illustrate the similarities to the inductive wireless power transfer (IWPT) solution and find that the same, but dual, expressions apply.

Electromagnetic Field Based WPT Technologies for UAVs: A Comprehensive Survey

“…Their device was more suitable for a multi-band wireless charging system than previous single-band studies. Similarly, Minnaert et al in [69] proposed a method to determine closed-form expressions for a CCWPT system with one transmitter and two receivers. They determined the optimal condition for both maximum power transfer and maximum power delivered.…”

Capacitive Wireless Power Transfer with Multiple Transmitters: Efficiency Optimization

“…Substituting the derivatives of Equations (15) and (17) to v re n and v im n into the system Equations (21) and (22), and taking into account Equation 18…”

“…Efficiency maximization for CPT was already solved for a single transmitter with multiple receivers (SIMO: single-input multiple-output) [22,23], but to date, an analysis specifically for a CPT system with multiple (coupled) transmitters (MISO) is lacking.…”

Optimizing the Power Output for a Capacitive Wireless Power Transfer System with $N$ receivers

“…If a single (N =1) or two (N =2) receivers are present, the analytical expressions are reduced to the same expressions found in [2] and [3], respectively, for a CWPT system with one transmitter and a single or two uncoupled receivers.…”

“…In this work, only the first configuration is studied: the optimal solution for maximizing the power transfer for a general CWPT system with one transmitter and multiple receivers is analytically determined. This was already done for a system with a single receiver [2] or two receivers [3], but now the work is extended to N receivers. Closed-form expressions for the optimal terminating loads and the corresponding maximum power transfer are determined from general maximum power transfer theories [4], [5] and applied on the case of capacitive charging.…”