This paper presents the study and detailed analysis of converter losses at different stages together with the series-series (S-S) compensating coils in wireless power transfer (WPT) systems, via two distinct approaches to control the power converters. The two approaches towards wireless DC–DC power flow control are termed as the Single Active High-Frequency Wireless Power Transfer (SAHFWPT) system and the Dual Active High-Frequency Wireless Power Transfer (DAHFWPT) system. The operation of converters in SAHFWPT and DAHFWPT are controlled by the extended phase shift (EPS) and dual phase shift method respectively. The general schematic of the SAHFWPT system consists of an active bridge and a passive bridge, while the schematic of the DAHFWPT system consists of both active bridges. The efficiency evolutions of ideal SAHFWPT and DAHFWPT are far away from the real ones. Moreover, this article analyzes the operation and losses of the uni-directional power flow of the WPT system, i.e., from the DC bus in the primary side to the battery load in the secondary side. The loss estimation includes high-frequency switching losses, conduction losses, hard turn on and turn off coil losses, etc. Moreover, the efficiency of the WPT system depends on operation of the converter. A 50 W–3600 W Power range system at a resonant frequency of 85 kHz is implemented in MATLAB/SIMULATION to demonstrate the validity of the proposed method.

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The advancements in the charging strategy of electric vehicles will have inevitable effects on the electric grid in the coming future. Electric vehicle battery chargers are able to perform the bidirectional power transfer according to the vehicle-to-grid concept and will offer valuable services to the distribution grid or to the domestic grid of the vehicle owner. The wireless power transfer battery chargers offer the opportunity for a more safe and user-friendly approach to electric vehicles for people who are not confident with technological apparatuses. Bidirectional wireless power transfer chargers capable of vehicle to grid services are the natural evolution of the above-mentioned concepts. This paper faces the topic of developing the control strategy for such a battery charger, focusing on the needs of the power conversion stages involved in the functioning of a charger enabled for vehicle to home operation. At first, the separation of the control strategy into two levels is explained, and then the interaction between the algorithms of the internal and external level is introduced. In implementing the control algorithms, it was decided to design controllers as simple as possible. This made it possible to adopt techniques well known in the scientific community for their design and to contain the computational resources needed for their implementation. Despite the simplicity of the controllers, the introduction and the management of the interactions between the various algorithms led to the development of an overall control strategy that at the same time respects the voltage and current limits set by the grid and the battery and also avoids exceeding the maximum operating conditions of the static converters that constitute the system. The algorithms and the relevant controllers are developed one by one in the continuous time domain, using techniques based on the analysis of Bode diagrams of the transfer functions involved in the operation of the system. In designing the controllers, the effects of their subsequent implementation in a discrete time domain are considered together with the effects of the transmission delay originated by the data exchange between the two sections of the system. The discretization of the controllers has been performed using the Tustin method. The performance of all the algorithms has been separately verified in the discrete time domain using simulations developed in the Matlab/Simulink environment. Finally, the functioning of the complete control strategy has been successfully checked in the same environment.INDEX TERMS Electric vehicle, vehicle to home, wireless power transfer, bidirectional power transfer. I. INTRODUCTIONAccording to the current trends of technological advancement, electric vehicles (EVs) are proposed as a solutionThe associate editor coordinating the review of this manuscript and approving it for publication was Qi Zhou.for future transport that promises energy saving and a contribution to reducing greenhouse gases. Indeed, the Global EV outlook 2021 reports th...

Two different arrangements for Wireless Battery Charging Systems (WBCSs) with a series-parallel resonant topology have been analyzed in this paper. The first arrangement charges the battery by controlling the receiver-side rectifier current and voltage without a chopper, while the second arrangement charges it with a chopper while keeping the chopper input voltage constant. The comparison of these two arrangements is made based on their performance on various figures of merit, such as the sizing factor of both the supply voltage source and receiver coil, overall system efficiency, power-transfer ratio, receiver efficiency, and cost estimation. Later, the simulated study is verified by the experimental setup designed to charge the electric vehicle.