Loganathan Balaji

This paper presents an advanced grid-connected electric vehicle (EV) charging system incorporating bidirectional battery energy storage and an adaptive butterfly optimization algorithm (ABOA)-tuned PI controller for DC-link voltage regulation and bidirectional power-flow control. The proposed architecture consists of a PWM rectifier for AC/DC conversion with near-unity power factor and reduced input current harmonics. A high-frequency inverter and isolation transformer provide compact and efficient isolated power transfer for EV charging applications. The major contribution of this work is the implementation of an ABOA-tuned PI controller that dynamically optimizes PI gains to maintain stable DC-link voltage under varying load conditions and battery operating states. The adaptive optimization process minimizes voltage error, overshoot, settling time, and ripple, thereby improving transient response and converter performance. MATLAB/Simulink simulation results demonstrate that the proposed controller achieves superior performance compared with conventional PI, PID, fuzzy logic controller, artificial neural network, particle swarm optimization, genetic algorithm, sliding mode control, and model predictive control-based control methods, achieving a settling time of 0.089 s, conversion efficiency of 98.5%, and total harmonic distortion of 0.6%. Hardware implementation using dsPIC30F4011 digital controllers validates the practical feasibility of the proposed system, showing relationship between simulation and experimental results in terms of DC-link stability, bidirectional energy management, and EV charging performance. Overall, the proposed ABOA-tuned PI controller provides a computationally efficient and cost-effective solution for next-generation smart EV charging infrastructures with improved dynamic stability, power quality, and energy efficiency.

A compact, four-element planar MIMO (Multiple Input, Multiple Output) antenna that operates in an ultra-wideband is presented for diversity application. The orthogonal position of the unit cells replicates the single antenna thrice, thereby decreasing mutual coupling. A UWB MIMO antenna measuring 35 × 35 × 1.6 mm³ is built using a microstrip line (50 Ω impedance) on an FR4 substrate having a thickness of 1.6 mm. The ground plane and radiator of this antenna are adjusted in several ways to bring it within its operating constraints between the frequencies of 3.1 GHz and 10.6 GHz. This technique makes the antenna small and covers the entire ultra-wideband (UWB) frequency range. The NI USRP was used to test the proposed MIMO antenna to determine its real-time performance. Based on the computed results, we conclude that this proposed antenna has outstanding characteristics in terms of performance and is suitable for wireless ultra-wideband indoor communication and diversity utilization with a small size.

In this paper, we introduce a four-port self-isolated UWB MIMO antenna for diversity applications. First, we have developed a basic radiating element of the proposed antenna in four stages of design, where patches of geometrically different shapes were added at each stage to arrive at the final radiator form. The antenna was designed on an FR-4 substrate with a compact size of 28 × 28 × 1.6 mm³. A tapered microstrip feeding was employed to enhance the antenna’s impedance matching. An orthogonal arrangement of the four radiators was adopted to mitigate the mutual coupling between them, avoiding the use of a separate isolation structure. A prototype was built and measured with a close agreement between the experimental and simulated results. The MIMO antenna performed well in the entire frequency spectrum of 3.1–10.6 GHz, with an isolation better than 20 dB. The measured envelope correlation coefficient (ECC) was less than 0.001, the diversity gain (DG) was greater than 0.99 dB, and the total active reflection coefficient (TARC) was less than −10 dB. The performance of the proposed antenna design was compared with existing designs. The comparison showed that the proposed quad-element UWB MIMO array is compact, has good isolation and diversity performance compared to existing designs, and is well-suited for wireless diversity applications.