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

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

This paper reviews the current status and implementation of battery chargers, charging power levels, and infrastructure for plug-in electric vehicles and hybrids. Charger systems are categorized into off-board and on-board types with unidirectional or bidirectional power flow. Unidirectional charging limits hardware requirements and simplifies interconnection issues. Bidirectional charging supports battery energy injection back to the grid. Typical on-board chargers restrict power because of weight, space, and cost constraints. They can be integrated with the electric drive to avoid these problems. The availability of charging infrastructure reduces on-board energy storage requirements and costs. On-board charger systems can be conductive or inductive. An off-board charger can be designed for high charging rates and is less constrained by size and weight. Level 1 (convenience), Level 2 (primary), and Level 3 (fast) power levels are discussed. Future aspects such as roadbed charging are presented. Various power level chargers and infrastructure configurations are presented, compared, and evaluated based on amount of power, charging time and location, cost, equipment, and other factors.

/pdf/review-of-battery-charger-topologies-charging-power-levels-85yy2igx2w.pdf

Review of Battery Charger Topologies, Charging Power Levels, and Infrastructure for Plug-In Electric and Hybrid Vehicles

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

Power electronics

This work is devoted to review and analyze the most relevant characteristics of multilevel converters, to motivate possible solutions, and to show that we are in a decisive instant in which energy companies have to bet on these converters as a good solution compared with classic two-level converters. This article presents a brief overview of the actual applications of multilevel converters and provides an introduction of the modeling techniques and the most common modulation strategies. It also addresses the operational and technological issues.

/pdf/the-age-of-multilevel-converters-arrives-izieu77jn6.pdf

The age of multilevel converters arrives

This paper presents a new cell module for modular multilevel converter (MMC) used in electric vehicles application. Traditionally, MMC has been used in high-power high-voltage application. The large number of power electronic devices required is rather used for reducing their voltage stress than the harmonic contents. Using the proposed cell topology, higher numbers of levels are achieved while the number of component remains low. This characteristic makes it an ideal configuration for a low switching high-efficiency AC/DC power converter, required for the soon to be common for plug-in vehicles application. Such converter can play two roles, not only can it be used as an active bidirectional charger, but also as active filter increasing network reliability. A predictive control algorithm is also presented in this paper, which will demonstrate the possibility to impose a charging curve on the DC side, even when the converter is used as active filter

Efficient MMC Devices with Reduced Radiated and Conducted Interferences for Electric Vehicles Application

This article presents an application of a four-leg voltage source converter (VSC) in a distribution network for the mitigation of power quality problems such as burden reactive power, unbalanced load, waveform distortion, and flow of high neutral currents. Fast and accurate compensation depends upon the used control algorithm for estimation of fundamental load currents. Classical theory-based enhanced phase-locked loop (EPLL) control algorithm is applied for estimation of fundamental components of distorted load current. In this algorithm, extracted fundamental load current components are applied for extraction of reference supply currents. The VSC is controlled using a digital signal processor (DSP) for implementation of control algorithm for the compensation of reactive linear and nonlinear loads. Test results on a developed VSC-based system are presented to prove the functions for improving the power quality.

Application of Voltage Source Converter for Power Quality Improvement

In this paper, the design and implementation of a model reference adaptive control (MRAC) applied to a three-phase three-level boost-type Vienna rectifier are presented. The proposed adaptive controllers are designed for inner loops, targeting to balance partial output DC bus voltages, while maintaining unity power factor and minimum AC line currents harmonics. The dqo nonlinear multiple-input multiple-output (MIMO) state space model of the rectifier is first over- parameterized. Then, the controllers are designed based on adequate input-to-output linearization and Lyapunov-based parameters adaptation scheme, with a view to track the reference model and compensate the system parametric variations. The outer voltage loop is set consequently, assuming fast inner loops dynamics. The proposed control law is designed in Simulink/Matlab and executed in real- time on a 1.5 kW laboratory prototype using the DS1104 controller board of dSPACE. The experimental results are given under various operating conditions, including steady state operation at different power levels, unbalanced DC load steps, temporary phase loss and plusmn30% AC supply voltage dip/swell. The proposed control law ensures low output voltage ripple, minimum AC line-current THD, small overshoots and fast settling times, face to a wide clan of disturbances.

A DSP-Based Implementation of a Nonlinear Model Reference Adaptive Control for a 1.5 kW Three-Phase Three-Level Boost-Type Vienna Rectifier

The presented article introduces a versatile multilevel inverter based on Packed E-Cell (PEC) topology. This structure is suitable for conversion of photovoltaic energy generations to supply AC loads and uninterruptible power supplies (UPS). Requiring a reduced number of power switches and capacitors compared to other inverters along its control simplicity are the prominent merits of this converter. Thanks to the horizontally extension of the shunt-capacitors, both of them can be charged or discharged to a quarter if the input source, at the same time. Hence, by applying two isolated input sources and one voltage sensor, the proposed inverter generates 17-levels for the output voltage. Simple level shifted pulse width modulation technique (LS-PWM) is used to control the operation of the proposed inverter. Finally, the accurate performance of the proposed multilevel structure is investigated through MATLAB simulations.

Kamal Al-Haddad

Papers

Efficient MMC Devices with Reduced Radiated and Conducted Interferences for Electric Vehicles Application

Application of Voltage Source Converter for Power Quality Improvement

A DSP-Based Implementation of a Nonlinear Model Reference Adaptive Control for a 1.5 kW Three-Phase Three-Level Boost-Type Vienna Rectifier

Circuit Reconfiguration of Packed E-Cell Multilevel Inverter for Renewable Energy Applications

Looking Back on 65 Years of IES and on to the Future [Message from the President]