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In real applications, it is usually desirable to have a regulated dc output voltage from a wireless power transfer (WPT) system. This voltage regulation is especially necessary because of possible variation in coupling coil relative position and thus a changing mutual inductance. For WPT systems working at megahertz (MHz), Class E rectifiers are known to be advantageous, thanks to their simple configuration and soft-switching operation. In this paper, we propose a new Class-E-based active rectifier. This rectifier is capable to simultaneously perform high-efficiency rectification and output voltage regulation, but without the need to have an additional regulating circuit. Analytical derivations and analysis are provided to explain the operation principle in detail. Guidance is also developed for a balanced design of parameters, which compromises among different criteria. Final experiments validate the analytical analysis and dc output voltage regulation via the active rectifier. With the duty cycle control of the rectifier, a constant output voltage (10 V) can be maintained under a varying mutual inductance coefficient and with more than 92% rectifying efficiency. [ABSTRACT FROM AUTHOR]

This paper proposes and implements autonomous control of a multiple-receiver wireless charging system. The charging control problem is challenging due to the decentralized nature of the system, possible changing numbers and types of energy storage devices as loads of the receivers, and complexity in wireless power distribution mechanism. The game-theory-based control is developed that fully respects the unique characteristics of the transmitter (i.e., charger) and receivers. The preferences of the individual devices are first quantified using utility functions. Then, the charging control problem is formulated as a generalized Stackelberg game considering the leader–follower relationship between the transmitter and receivers, and the limited total charging power. At each control instant, the generalized Nash equilibrium among the receivers, i.e., charging power distribution here, is reached by searching the Lagrange multiplier while the total charging power from the transmitter is updated in a step-by-step manner. Both simulation and experimental results show that the proposed charging control autonomously manages and updates the power distribution in the cases where the receivers with different energy storage devices quit or join the wireless charging. [ABSTRACT FROM PUBLISHER]

This paper develops a novel voltage equalizer by combining wireless power transfer (WPT) and a voltage multiplier (VM) for series-connected energy storage cells. The physical isolation achieved by WPT can offer several unique benefits that traditional equalizers can hardly provide. In this paper, the characteristics of a multiple-output VM are analytically discussed and used to develop an equivalent one-output VM model. Based on this model, parameters of the WPT system are properly designed. The proposed design methodology can achieve a single-switch voltage equalizer without feedback control, which dramatically decreases the circuit complexity and cost. Moreover, this methodology can naturally ensure a robust system under small coil misalignment. In the experiment, the proposed system is built to balance four series-connected ultracapacitor modules. The system efficiency is 72.8% at a load power level of 10 W. [ABSTRACT FROM PUBLISHER]