Resonant converters (RCs) are perceiving global interests of the research community for its eminent contribution in design of many industrial and commercial applications. Rich literature and well-established technology is available to define the role of RCs in such applications where the load is predominantly passive and resistive. However in applications like charging, the nature of load is often interpreted as capacitive and the knowledge on how a RC reciprocates to such variable, non linear load is limited. Motivated by this, the paper investigates about 25 capacitive loaded resonant structures and each of them is thoroughly analyzed to evaluate various key parameters like the output current, peak input current, and current gain. A comparative study is done to categorize and organize these topologies in regard to each of the said parameters. This provides a quick overview of various resonant converter topologies and helps designers to choose a structure that may fit their application. To this base knowledge, the study is further narrowed down to find suitable topology for charging application and accordingly proposed a novel fourth-order RC topology called LA7. A hardware prototype was built to compare and validate the simulated and measured performances.

As the world is moving towards green transportation, an effective charging infrastructure is needed to meet the demand of electric vehicles (EVs) with different power ratings. High power DC charging will facilitate EVs to charge quickly and reduce the wait time of a customer. As present charging infrastructure is limited to low power and is not compatible with different rated modular battery packs of EVs, this paper demonstrates Resonant Converter (RC) based high power constant current DC Fast charger. Owing to its inherent sensitivity, RCs suffer and fail to maintain rated load current when subjected to deviation in switching frequency and this has been the limiting feature for which they are not explored much in the automobile sector. In light of it, a topology study of about 25 RCs under lumped T, π, Ladder, and branch type structures is reported and examined the frequency dependence of different characteristic parameters in a range of frequencies encompassing the resonant frequency. This investigation conceived a novel RC that has adequate immunity in dealing with frequency sensitivity and also capable of pumping high DC power. The proposed converter is verified with a prototype and results are in close agreement with design.

Constant current (CC), constant voltage (CV), and constant power (CP) find numerous applications in different stages of the power supply chain and are often a part of various industrial and commercial needs. Although several conventional power supplies are available in the market to provide CC, CV, and CP, their outputs are specific and limited to one or two of these power modes. In light of this, this paper introduces a multipurpose power supply that can deliver power in all three modes (CC, CV, and CP) irrespective of load dynamics. A novel branch type resonant converter comprising three inductors and a capacitor is investigated for the design and development of the power supply. Consumers can choose their preferred mode of operation by switching the operating frequency. This multipurpose power supply subsidizes the space, technology, time, and economy required for three individual supplies and bags magnificent features such as simple control with efficiency greater than 95% in the CC mode and above 80% in CV and CP modes, subjected to loading constraints. The versatility of the power supply is validated by a hardware prototype tested at different load conditions. Regardless of the changes in load resistance, the proposed power supply remained rigid and efficient in each of the mentioned modes.

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