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

Abstract

One of the greatest challenges to power embedded devices using magnetically coupled resonant wireless power transfer (WPT) system is that the amount of power delivered to the load is very sensitive to load impedance variations. Previous adaptive impedance-matching (IM) technologies have drawbacks because adding IM networks, relay coils, or other compensating components in the receiver-side will significantly increase the receiver size. In this paper, a novel frequency-tracking and impedance-matching combined system is proposed to improve the robustness of wireless power transfer for embedded devices. The characteristics of the improved WPT system are investigated theoretically based on the two-port network model. Simulation and experimental studies are carried out to validate the proposed system. The results suggest that the frequency-tracking and impedance-matching combined WPT system can quickly find the best matching points and maintain high power transmission efficiency and output power when the load impedance changes.

Detecting Load Resistance and Mutual Inductance in Series-Parallel Compensated Wireless Power Transfer System Based on Input-Side Measurement

“…According to (3) and (4), λ becomes (9) can be simplified as 2 10 (10) into (5), the coefficients of (5) are…”

“…Through magnetic coupling between transmitting and receiving coils, wireless power transfer (WPT) technique can deliver electrical energy from a source to a load without any electric wire [1,2]. To improve system efficiency, compensation is needed to nullify inductive reactance.…”

Control Strategy for Vehicle Inductive Wireless Charging Based on Load Adaptive and Frequency Adjustment

“…When the system satisfies the Equation (14), frequency bifurcation can be avoided. Moreover, the quality factor of the secondary border of the frequency bifurcation critical point is obtained as follows:…”

Method for Estimating Optimum Free Resonant Frequencies in Overcoupled WPT System

“…Figure 2 shows an equivalent circuit model of a twocoil WPT system, where the controllable elements include voltage source V , source impedance R , load impedance R , primary coil 1 , secondary coil 2 , and capacitances of primary and secondary resonators, 1 and 2 . Depending on the circuit elements, various methods have been introduced to improve the PTE and output power of the WPT system [6][7][8][9][10][11][12][13]. These methods are categorized in two types: a method that changes the critical coupling coefficient [6][7][8][9][10] and a method that mitigates the equivalent coupling coefficient in the overcoupled state [11][12][13].…”

“…Changing the amplitude of the voltage source does not improve the PTE, while changing the operating frequency in overcoupled state achieves the high PTE [11,12]. However, this method may result in the violation of frequency regulation for a WPT system in narrow bandwidth.…”