Wireless power transfer (WPT) is a power transfer technique widely used in many industrial applications, medical applications, and electric vehicles (EVs). This paper deals with the dynamic modeling of the resonant inverter employed in the WPT systems for EVs. To this end, the Generalized State-Space Averaging and the Laplace Phasor Transform techniques have been the flagship methods employed so far. In this paper, the modeling of the resonant inverter is accomplished by using the novel Modulated Variable Laplace Transform (MVLT) method. Firstly, the MVLT technique is discussed in detail, and then it is applied to model a study-case resonant inverter. Finally, a study-case resonant inverter is developed and utilized to validate the theoretical results with MATLAB/Simulink.

The one-element resonant topologies of the wireless battery chargers (WBCs) for electric vehicles (EVs) are analyzed with the aim of giving both a thorough assessment and a comprehensive comparison of the performance of the topologies. The analysis is carried out in terms of the following performance indexes: efficiency versus power injected in the EV battery, power sizing factor of the supply inverter, power sizing factor of the transmitter and receiver coil set, current sizing factor of the supply inverter, and behavior under the extreme conditions of open- and short-circuited operation of the receiver. At first, the two topologies with series resonance of the receiver coil and series/parallel resonance of the transmitter coil are investigated and their performance indexes are formulated. Then, the investigation is extended to the two topologies with parallel resonance of the receiver coil and series/parallel resonance of the transmitter coil. Afterward, merits and limits of the topologies are discussed. Measurements obtained from series-series and series-parallel WBC setups are given that corroborate the theoretical findings.

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.

The paper deals with the wireless battery chargers (WBCs) of electric vehicles (EVs) and refers to a resonant WBC that utilizes a rectifier-chopper stage in the receiver side to control the charging current/voltage of the EV battery. Two topologies, namely series-series and series-parallel, are considered, and their performance in terms of efficiency and power sizing is investigated. Power sizing is formulated for both the power source and the coil coupling set. Instrumental in the investigation is the proper modeling of the rectifier-chopper stage. Data used for calculating the performance are obtained from a WBC setup for electric city-car. Comparison of the results reveal the overall convenience of the series-series topology.

Currently, due to its various applications, the high-performance isolated dc-dc converter is in demand. In applications where unidirectional power transfer is required, the single active bridge (SAB) is the most suitable one due to its simplicity and ease of control. The general schematic of the SAB converter consists of an active bridge and a passive bridge, which are connected through a high-frequency transformer thus isolated. The paper summarizes the behavior of this converter in its three operation modes, namely the continuous, discontinuous, and boundary modes. Later, the features of this converter, such as its input-to-output and external characteristics are discussed. Input-to-output characteristics include the variation of converter output power, voltage, and current with an input control variable i.e., phase-shift angle, whereas the external characteristic is the variation of the output voltage as a function of output current. In this discussion, the behavior of this converter in its extreme operating conditions is also examined. The features of the characteristics are elucidated with the help of suitable plots obtained in the MATLAB environment. Afterward, the specifications of a SAB converter are given and, based on the results of the analysis, a detailed design of its electrical elements is carried out. To validate the features and the design procedures presented in this paper, a prototype is developed. An element-wise loss estimation is also carried out and the efficiency of the converter has been found to be approximately equal to 93%. Lastly, the test was executed on this prototype, confirming the theoretical findings concerning this converter.

Inductive Power Transfer (IPT) is a promising solution for charging the electric vehicles (EVs). The first IPT systems (IPTSs) were needing a strong coupling between transmitter and receiver coils to achieve a satisfactory efficiency in the power transfer. Nowadays this drawback has been overcome by the resonant technology, which ensures an efficiency higher than 90% even with loosely coupled coils. Enforcement of this result requires that the transmitter and receiver stages of the IPTSs have the same resonance frequency, and that the supply frequency of the IPTSs coincides with the resonance one. In practice, any deviation in the values of the reactive parameters of the IPTSs produces a mismatch between supply and resonance frequency. This paper analyzes the impact of such a mismatch on both the efficiency and the power supply sizing factor of an IPTS with series-series resonant topology. The analysis embraces the mismatches ensuing from an update of the supply frequency to make resonating either the transmitter stage or the receiver stage or the IPTS input impedance. Throughout the paper, the IPTS developed to charge an electric city-car is taken as a study case.