Self-tuning Wireless Power Transmission Scheme Based on On-line Scattering Parameters Measurement and Two-side Power Matching

Abstract

Sub-resonances often happen in wireless power transmission (WPT) systems using coupled magnetic resonances (CMR) due to environmental changes, coil movements or component degradations, which is a serious challenge for high efficiency power transmission. Thus self-tuning is very significant to keep WPT systems following strongly magnetic resonant conditions in practice. Traditional coupled-mode ways is difficult to solve this problem. In this paper a two-port power wave model is presented, where power matching and the overall systemic power transmission efficiency are firstly defined by scattering (S) parameters. Then we propose a novel self-tuning scheme based on on-line S parameters measurements and two-side power matching. Experimental results testify the feasibility of the proposed method. These findings suggest that the proposed method is much potential to develop strongly self-adaptive WPT systems with CMR.

Enhancing the Robustness of the Wireless Power Transfer System to Uncertain Parameter Variations Using an Interval-Based Uncertain Optimization Method

“…Many works [12][13][14][15][16][17][18][19] have been done to improve the performance of the WPT system with uncertain parameters. In [12], an adaptive frequency-tracking technique is proposed to address coil distance and orientation variations.…”

“…Because the frequency tracking technique can only be used when the coils are strongly coupled [13,14], impedance matching network methods [15,16] using energy-storage components are proposed. In [15], an impedance matching network was inserted into the transmitter-circuit so that the impedance of the transmitter can be dynamically matched to the source impedance.…”

“…Although these methods can improve the performance of the WPT system with uncertain parameter variations, there still exist some drawbacks: (1) To deal with uncertain parameter variations, an active compensation system (like frequency tracking system, automatic impedance matching system, and H ∞ control system, etc.) is needed [12][13][14][15][16][17][18][19]. However, introducing the active compensation system will obviously increase the size, control difficulty, and energy losses of the overall WPT system.…”

“…Using the proposed method, the WPT system can achieve good robustness to uncertain parameter variations. Compared with previous methods [12][13][14][15][16][17][18][19], the proposed method only uses passive compensation networks (Q-type impedance matching networks). The structure and control difficulty of the overall WPT system can be reduced.…”

A Frequency-Tracking and Impedance-Matching Combined System for Robust Wireless Power Transfer

“…Many works have been done on the adaptive impedancematching technology for the WPT system, including the following: (1) adjusting the source operating frequency until the output power of the WPT system is maximized [11][12][13][14], (2) adding variable impedance-matching networks in the WPT system to transform the input and output impedance to optimal values [15][16][17][18], (3) optimizing the mutual inductance between coils using multicoil topology [19][20][21][22][23], and (4) using a receiver-side switching converter to transform the actual load resistance into optimal load resistance [5,[24][25][26].…”