There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

http://ieeexplore.ieee.org/iel5/5610941/5624686/05624745.pdf

Power electronics

The use of microbial fuel cells to generate electrical current is increasingly being seen as a viable source of renewable energy production In this Progress article, Bruce Logan highlights recent advances in our understanding of the mechanisms used by exoelectrogenic bacteria to generate electrical current and the important factors to consider in microbial fuel cell design There has been an increase in recent years in the number of reports of microorganisms that can generate electrical current in microbial fuel cells Although many new strains have been identified, few strains individually produce power densities as high as strains from mixed communities Enriched anodic biofilms have generated power densities as high as 69 W per m2 (projected anode area), and therefore are approaching theoretical limits To understand bacterial versatility in mechanisms used for current generation, this Progress article explores the underlying reasons for exocellular electron transfer, including cellular respiration and possible cell–cell communication

Exoelectrogenic bacteria that power microbial fuel cells

Solar Engineering Of Thermal Processes

Novel LY Converter Topologies for High Gain Transfer Ratio - A New Breed of XY Family

This study introduces a new single phase nine-level inverter using two capacitors and a single DC source. Voltage imbalances in the capacitors are eliminated using two control algorithms namely charging algorithm and discharging algorithm. The charging algorithm is used to change the inverter switching states when the measured voltage across the capacitors is less than the prescribed value. Alternatively, if the voltage across the capacitors is greater than the set value, the discharging algorithm determines the switching pattern of the inverter switches. The proposed voltage balancing algorithm is very simple to implement and makes the proposed inverter attractive for industrial applications. An extensive comparison of the proposed inverter is made against other topologies proposed in the literature in terms of the components used. The proposed inverter is tested in both standalone and grid connected modes. The proposed inverter is simulated and implemented as a prototype in the laboratory. Experimental results obtained from the prototype confirm the high-quality transient performance of the proposed inverter in terms of its dc capacitor voltage balancing capability.

Single phase nine level inverter using single DC source supported by capacitor voltage balancing algorithm

In this paper hybrid non isolated/ non inverting Nx interleaved DC-DC multilevel Boost Converter for renewable energy applications is presented. The presented hybrid topology is derived from the conventional interleaved converter and the Nx Multilevel boost converter. In renewable energy applications, generated energy cannot be directly used at application end. In most of the cases it needs to be stepped up with DC-DC converter at operating voltage levels as per the requirement of the application. Though conventional boost converter can theoretically be used for this purpose, but obtaining such high gain implies that boost converter should operate at it its maximum duty cycle, which is not feasible due to the great variations in the output voltage caused by small variations in the duty cycle, leading the boost converter to instability and also increases the voltage stress across switches. The advantages of presenting topology of DC-DC converter are high voltage conversion, reduce ripple, low voltage stress, non inverting without utilizing the high duty and transformer. The main advantage of presented topology is more number of levels can be increased by adding capacitor and diode circuitry to increase the voltage gain without disturbing the main circuit. Moreover, the presented topology is compared with several recent high gain converters. The proposed topology is simulated in MATLAB/SIMULATION and results will verify the validity of the design and operation of the converter.

Hybrid non-isolated and non inverting Nx interleaved DC-DC multilevel boost converter for renewable energy applications

Photovoltaic (PV) water pumping systems are becoming popular these days. In PV water pumping, the role of the converter is most important, especially in the renewable energy-based PV systems case. This study focuses on one such application. In this proposed work, direct current (DC) based intermediate DC-DC power converter, i.e., a modified LUO (M-LUO) converter is used to extricate the availability of power in the high range from the PV array. The M-LUO converter is controlled efficiently by utilizing the Grey Wolf Optimizer (GWO)-based maximum power point tracking algorithm, which aids the smooth starting of a brushless DC (BLDC) motor. The voltage source inverter’s (VSI) fundamental switching frequency is achieved in the BLDC motor by electronic commutation. Hence, the occurrence of VSI losses due to a high switching frequency is eliminated. The GWO optimized algorithm is compared with the perturb and observe (P&O) and fuzzy logic based maximum power point tracking (MPPT) algorithms. However, by sensing the position of the rotor and comparing the reference speed with the actual speed, the speed of the BLDC motor is controlled by the proportional-integral (PI) controller. The recent advancement in motor drives based on distributed sources generates more demand for highly efficient permanent magnet (PM) motor drives, and this was the beginning of interest in BLDC motors. Thus, in this paper, the design of a high-gain boost converter optimized by a GWO algorithm is proposed to drive the BLDC-based pumping motor. The proposed work is simulated in MATLAB-SIMULINK, and the experimental results are verified using the dsPIC30F2010 controller.

/pdf/a-high-gain-dc-dc-converter-with-grey-wolf-optimizer-based-5870g92h5c.pdf

A High Gain DC-DC Converter with Grey Wolf Optimizer Based MPPT Algorithm for PV Fed BLDC Motor Drive

A new single-phase 15-level inverter with a reduced number of components for the Solar PV application is proposed in this paper. It is incorporate the proposed inverter with a boost converter to extract energy from the solar PV modules, the proposed inverter aids to generate fifteen stepped output voltage levels with lower THD. The proposed inverter can improve efficiency and reduce losses, cost, and complexity of the overall system. The conventional boost converter will boost the output voltage to a maximum voltage from Solar PV with MPPT(P&O). The proposed inverter is tested experimentally using the dSPACE RTI 1104 controller along with MATLAB/Simulink. A detailed comparison with existing MLIs with the proposed inverter. The work presents experimental results not only to show its efficiency but also to the effectiveness under different circumstances of linear and non-linear loads. The inverter is stable during the non-linear loads and well suits for grid-connected systems.

/pdf/design-and-implementation-of-a-single-phase-15-level-32jupof9hk.pdf

Sanjeevikumar Padmanaban

Papers

Novel LY Converter Topologies for High Gain Transfer Ratio - A New Breed of XY Family

Single phase nine level inverter using single DC source supported by capacitor voltage balancing algorithm

Hybrid non-isolated and non inverting Nx interleaved DC-DC multilevel boost converter for renewable energy applications

A High Gain DC-DC Converter with Grey Wolf Optimizer Based MPPT Algorithm for PV Fed BLDC Motor Drive

Design and Implementation of a Single-Phase 15-Level Inverter With Reduced Components for Solar PV Applications