With the advancement in planar magnetic technology as well as wide band-gap (WBG) devices such as Gallium Nitride (GaN), Silicon Carbide (SiC) MOSFET and high electronic mobility transistor (HEMT), the utility of resonant converters has remarkably expanded. These converters can be used in applications requiring power density since they naturally possess zero voltage switching (ZVS) and zero current switching (ZCS) capabilities. Recently, they are gaining popularity in point-of-load (POL) DC-DC converter applications, such as electric vehicle (EV) chargers. As majority of the EV chargers are grid-connected, cascading a front-end (FE) AC-DC power factor corrected (PFC) converter with POLs becomes necessary. It is well-known in the literature that in cascaded systems, the impedance interaction of any FE converter with POL converters may lead to issues with system stability. The individual converters should be designed with sufficient stability margin to meet Middlebrook's stability criterion. Therefore, the knowledge of small-signal impedances becomes a prerequisite for applying the stability criterion. This paper focuses on determining the small-signal impedances of the LLC resonant converter, which are then used to analyze the stability of an EV charger employing the LLC resonant converter as a POL converter. The analysis is experimentally verified in a laboratory-developed prototype of 800W grid-connected EV charger.

With the advent of new electric vehicle technologies, research into electric vehicle chargers have also progressed immensely in the recent times. This paper discusses the modeling and design considerations involved in a bidirectional isolated electric vehicle charger. An electric vehicle charger comprises of a front end rectifier with power factor correction capability, with or without bidirectional feature cascaded with an isolated or non isolated DC-DC converter. The small signal impedance models of these converters are developed which aids in analysing the interaction between the two converters, while they try to meet their own control objectives. It is imperative to ensure that these interactions will not induce unintended oscillations at the DC link or instability in the cascaded system. Detailed simulation results of this cascaded system are presented to validate the analysis.

Various power conversion applications require the power converters to be cascaded with one another, to meet the load requirements. However, generally the trend is to cater to the control system design of individual converters and then cascade them with the other converters. Such cascaded systems can give sub optimal performance with poor stability margins. This paper tries to address this issue by investigating the interaction of the individual converters along with their control systems on the other converter, at their point of coupling. An active front end three phase rectifier cascaded with a voltage controlled buck converter is considered here to demonstrate the stability oriented control system design. Detailed impedance modeling of these converters are presented and their mutual interaction is studied for understanding the system stability. Extensive simulation results are presented to validate the analysis.

Current paper represents a new type of encrypted Electronic Patient Record (EPR) code used for data encryption and content protection. EPR is a collection of several private information related to a patient which needs data authenticity, data security as well as safe and secured transmission. The proposed methodology used both cryptography and image processing techniques to build a new type of encrypted information code in image format which can be transmitted and used like bar code, QR code but even more secure. The success rate of recovery of data is 100% for both short and long messages. The information can also be retrieved at the receiver side exactly same without any loss of information. Use of RSA and DES algorithm consequently, with three keys and followed by some image processing techniques like complement, flip make the proposed algorithm more unbreakable. In this paper a complete Graphical User Interface (GUI) has been developed for both encoder-transmitter and decoder- receiver section.

Current paper presents a new type of GUI based secure breast cancer identification system through a combination of Cryptography and Biomedical Image Watermarking. Through this scheme 2ndlevel of security can be applied for the embedded data in mammographic images. Several information related to patients (EPR), infected region (ROI), doctor's name and diagnosis from symptoms are encrypted in the 1stlevel using RSA encryption and then embedded in the mammographic image itself in the 2ndlevel using Bit Plane Slicing watermarking technique. The infected region is identified through region growing and contour detection algorithm which needs to be perfect for accurate ROI identification resulting a better treatment. Values of several image quality metrics show that the proposed GUI based breast cancer diagnostic system is good enough for successful recovery of all the embedded information exactly similar. The simplicity and easiness of the complete GUI also makes the entire system user friendly even to the non-medical technical person.