Chanuri Charin

Electric vehicles (EVs) are experiencing rapid global adoption driven by environmental concerns and fuel security. This article presents a new dual-source converter based on a hybrid modular multilevel configuration (DCHMMC) designed for optimal cell utilisation in EV battery systems. Contrary to conventional converters that can either charge or discharge the cells using a single source, thereby leaving several cells/modules (Ms) idle during each time step, the proposed converter enables the integration of two sources that can utilise the cells simultaneously. This dual source feature minimises idle cells/Ms, enhances energy efficiency, and supports flexible bidirectional power flow. The proposed converter operates in three distinct modes. The first involves dual-source charging for fast charging and improved vehicle availability. The second involves one source charging while the other discharges for dynamic operation. Finally, the last involves dual-source discharging for maximum power delivery and support vehicle-to-grid (V2G) operation. The simulation results demonstrated smooth multilevel sinusoidal output voltages (Vout_a and Vout_b), each with a peak of 350 V, generated simultaneously using 132 cells (six cells per M, 22 Ms). The total harmonic distortion (THD) values for Vout_a and Vout_b were 0.42% and 2.25%, respectively, confirming the high-quality performance. Furthermore, only 0–36 cells and 0–6 Ms were idle during operation, showing improved cell utilisation.

Performance evaluation of maximum power point tracking with a boost converter was presented in this paper. Several MPPT methods have recently been considered as alternatives to conventional MPPT methods, which have high steady-state oscillation and low efficiency. In order to solve the aforementioned issues, a soft computing method is suggested. Under MATLAB/Simulink, the efficiency of P&O, PSO and SSA was evaluated. The MPPT algorithms were tested under three main conditions which are under high irradiance (1000 W/m2), medium irradiance (600 W/m2,) and low irradiance (200 W/m2). Based on the simulation results, Salp Swarm Algorithm (SSA) method shows the best MPPT method with 89.95%, 99.90% and 98.38% tracking efficiency under high, medium and low irradiances respectively. SSA was the best method in terms of high efficiency, no steady-state oscillations and fast convergence.

Typically, busbars are used to transmit and distribute currents in a bus duct system. The alarming use of nonlinear loads in the industrial sector or at residentials, such as arc welding, computers, ballast lighting, variable speed drives, and so on, has resulted in the generation of harmonics in current distortion, which are uncontrolled and thus increase heat generation within the system. The research conducted in this paper focuses on the prediction of the heat distribution as well as the analysis on operating temperature of a single busbar with compliance to the British National and International Standard (BS 159: 2014) using the Finite Element Method (FEM) in COMSOL Multiphysics software. The copper busbar dimension used for this research was 20mm x 6mm x 300mm, and the fundamental Root Mean Square (RMS) current was 419.1 A. The size of this busbars can withstand the maximum current of 430 A at a maximum operating temperature of 90°C, which complies with the standard requirement. The fundamental current is injected with variation of total harmonic distortion in current up to 55% with an interval of 5%. According to the findings, the operating temperature increases in direct proportion to the increase in total harmonic distortion with the current injections. With the presence of 55% of total harmonics in the current, the current was increased up to 57.73 A from the fundamental current, while the operating temperature was increased up to 140C from the fundamental temperature. The total harmonics in current produced by the nonlinear loads could affect the operating temperature of the busbars, and this continuous operation of current flow will affect the busbars' lifespan due to the occurrence of overheating.

This paper presents a study of Deterministic Particle Swarm Optimization (DPSO) in maximum power point tracking. DPSO is applied to a standalone PV system with a boost converter. This method is implemented primary to solve the problem in conventional techniques such as Perturb and Observe (P&O) and Incremental Conductance (IC) in failure to detect optimum point under certain condition, fixed step-size and high steady-state oscillation. Deterministic method is applied to conventional Particle Swarm Optimization (PSO) and takes advantage over guiding the behaviour of the particles through experience. The velocity of the particle is predicted and evaluated until the optimum point is achieved. A standalone photovoltaic (PV) system is constructed with MATLAB Simulink and DPSO is deployed and tested by simulation. The effectiveness of DPSO is evaluated under uniform condition at standard test condition (STC), medium and low irradiance. The results show that the DPSO successfully converge at optimum point with low steady-state oscillation, and it has high efficiency.

This paper presents a modified Levy particle swarm optimization (MLPSO) to improve the capability of maximum power point tracking (MPPT) under various partial shading conditions. This method is aimed primarily at resolving the tendency to trap at the local optimum particularly during shading conditions. By applying a Levy search to the particle swarm optimization (PSO), the randomness of the step size is not limited to a specific value, allowing for full exploration throughout the power-voltage (P-V) curve. Therefore, the problem such as immature convergence or being trapped at a local maximum power point can be avoided. The proposed method comes with great advantages in terms of consistent solutions over various environmental changes with a small number of particles. To verify the effectiveness of the proposed idea, the algorithm was tested on a boost converter of a photovoltaic (PV) energy system. Both simulation and experimental results showed that the proposed algorithm has a high efficiency and fast-tracking speed compared to the conventional HC and PSO algorithm under various shading conditions. Based on the results, it was found that the proposed algorithm successfully converges most rapidly to the global maximum power point (GMPP) and that the tracking of GMPP under complex partial shading is guaranteed. Furthermore, the average efficiency for all test conditions was 99% with a tracking speed of 1.5 s to 3.0 s and an average output steady-state oscillation of 0.89%.

This paper presents a novel modified Levy flight optimization for a photovoltaic PV solar energy system. Conventionally, the Perturb and Observe (P&O) algorithm has been widely deployed in most applications due to its simplicity and ease of implementation. However, P&O suffers from steady-state oscillation and stability, besides its failure in tracking the optimum power under partial shading conditions and fast irradiance changes. Therefore, a modified Levy flight optimization is proposed by incorporating a global search of beta parameters, which can significantly improve the tracking capability in local and global searches compared to the conventional methods. The proposed modified Levy flight optimization is verified with simulations and experiments under uniform, non-uniform, and dynamic conditions. All results prove the advantages of the proposed modified Levy flight optimization in extracting the optimal power with a fast response and high efficiency from the PV arrays.

We report the development of two epilayers namely the baseline highly strained channel and enhanced low gate leakage samples. The Hall data shows that the enhanced epilayer portraying higher sheet carrier concentration, but comparable carrier mobility in the 2-DEG layer, as compared to the baseline sample. The WinGreen simulation also conformed the enhanced epilayer advantages where wider Schottky barrier is observed and subsequently double carrier concentration is simulated in the channel. Both samples show low AuGe/Au Ohmic contact resistivity of approximately 0.16 Ω.mm. A tremendous advantage on 1 μm Schottky gate leakage is also recorded on enhanced epilayer where the leakage is more than seven times lower than that of the baseline sample. The resulted characteristics are much better than the reported submicron device, thus this device has find an important application in high-gain lossless transmission, especially in underwater optical communication system.

DC-DC converters are widely used in many applications such as power supplies, PV system, renewable energy systems and industrial applications. One of the main problems in dc-dc converters is the switching loss which affects efficiency and also the power density of the converter. To alleviate the switching loss problem this paper proposes novel soft switching PWM isolated dc-dc converters topology. The proposed full bridge dc-dc converter with active auxiliary circuit is designed and tested with full-bridge rectifier diode. The proposed converter is designed and evaluated in term of soft switching. In the proposed topology, the soft switching operations are achieved by charging and discharging process of the capacitor and additional switches. In the proposed topology, all the power switches operate under soft-switching conditions. Therefore, the overall switching loss of the power switches is greatly reduced. The output voltage of the converter is varied by PWM control. The effectiveness of the new converter topology is evaluated by experimental results of a laboratory scale down prototype. The obtained experimental results are found agreed with theoretical and soft switching is achieved.

Switched mode DC-DC converters are electronic circuits which convert a voltage from one level to a higher or lower level voltage. This paper presents a new solution approach to controller and observer controller of DC-DC Buck converter. The designs in this paper of DC-DC Buck converter is input voltage 20V step down to 12V output voltage. For control the system simulation investigation into development of controller and observer controller using MATLAB Simulink® software. The simulation develops of the controller and observer controller with mathematical model of DC-DC Buck converter. This paper also providing LQR controller to compare the performance of the system. Finally, the performance output voltage of DC-DC Buck converter is analyzed in terms of time response, overshoot and steady state error.