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

The many different techniques for maximum power point tracking of photovoltaic (PV) arrays are discussed. The techniques are taken from the literature dating back to the earliest methods. It is shown that at least 19 distinct methods have been introduced in the literature, with many variations on implementation. This paper should serve as a convenient reference for future work in PV power generation.

/pdf/comparison-of-photovoltaic-array-maximum-power-point-2nci76j6n4.pdf

Comparison of Photovoltaic Array Maximum Power Point Tracking Techniques

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

Power electronics

Review of the maximum power point tracking algorithms for stand-alone photovoltaic systems

This paper proposes a hybrid ac/dc micro grid to reduce the processes of multiple dc-ac-dc or ac-dc-ac conversions in an individual ac or dc grid. The hybrid grid consists of both ac and dc networks connected together by multi-bidirectional converters. AC sources and loads are connected to the ac network whereas dc sources and loads are tied to the dc network. Energy storage systems can be connected to dc or ac links. The proposed hybrid grid can operate in a grid-tied or autonomous mode. The coordination control algorithms are proposed for smooth power transfer between ac and dc links and for stable system operation under various generation and load conditions. Uncertainty and intermittent characteristics of wind speed, solar irradiation level, ambient temperature, and load are also considered in system control and operation. A small hybrid grid has been modeled and simulated using the Simulink in the MATLAB. The simulation results show that the system can maintain stable operation under the proposed coordination control schemes when the grid is switched from one operating condition to another.

A Hybrid AC/DC Microgrid and Its Coordination Control

In recent years, the power handling capability of EV chargers has been growing to reduce the charging time. In order to enhance the design and efficiency of EV chargers, an in-depth investigation of the losses caused in plug-in EV chargers is needed. This article presents an accurate loss model of a novel single-stage single-phase isolated PFC converter for a bidirectional EV charging application. The EV charger includes a current-fed full-bridge converter with bidirectional switches on the grid side with a swinging boost inductor that is affiliated with a full-bridge converter at the dc-side coupled via a high-frequency transformer. The AC-side current can be controlled to obtain power factor correction with low current total harmonic distortion (THD). The AC-side switches are naturally commutated and attained zero current switching (ZCS) without any external passive components. Additionally, zero current turn-ON is accomplished for DC-side switches to realize a high-efficiency EV charger. This is achieved with a modified control strategy and novel modulation method are adopted for achieving soft-switching operation and bidirectional power flow. To ensure that the proposed EV charger is feasible, experimental results with loss analysis of a 1.5 kVA unit are presented showing that the operation, analysis, and design are perfectly accorded.

An Accurate Loss Model of Single-Stage Single-Phase Isolated PFC Converter for Bidirectional Plug-in EV Charger

This paper proposed a dual DC bus nanogrid with 380 V and 48 V buses and allows the integration of distributed energy resources on two buses. The proposed system employs an interlink converter to enable power sharing between the buses. The integration of distributed energy resources has been found to enhance the reliability of the low-voltage bus in comparison to those that lack such integration. The integration process requires the introduction of a new V-I curve for the interlink converter within a DC nanogrid controlled by DC bus signaling and droop control. Furthermore, selecting a power electronics converter for the interlink converter is essential. This paper employs a dual active bridge with galvanic isolation as an interlink converter and proposes a control strategy for the converter that relies on DC bus signaling and droop control. Moreover, this control methodology serves the purpose of preventing any detrimental impact of the interlink converter on the DC buses through the reprogramming of the V-I curve. Subsequently, the suggested control methodology underwent simulation testing via MATLAB/Simulink, which included two different test categories. Initially, the DAB was evaluated as an interlink converter, followed by a comprehensive assessment of the interlink converter in a complete dual DC bus nanogrid. The results indicate that the DAB has the potential to function as an interlink converter while the suggested control approach effectively manages the power sharing between the two buses.

/pdf/a-droop-controlled-interlink-converter-for-a-dual-dc-bus-1ska3o77.pdf

A Droop-Controlled Interlink Converter for a Dual DC Bus Nanogrid with Decentralized Control

This paper proposes a novel zero-current assisted soft-switching bidirectional single-stage single-phase isolated power factor correction (PFC) based converter for plug-in EV charger. An isolated topology consists of a current-fed full-bridge converter with bidirectional switches on the ac-side that is connected with a full-bridge converter on the dc-side of a high-frequency transformer (HFT). HFT offers galvanic isolation for safety and high power density, and it is the most desired specification for a battery charger. The converter enables zero current switching (ZCS) of ac-side switches and zero current turn-ON for dc-side switches without any active clamp circuit or passive snubbers, which significantly reduced switching losses, footprints, and cost. The proposed modulation strategy and control technique are presented for promising the soft-switching operation of all semiconductor devices throughout the range for all modes with bidirectional power flow capability. These merits make the converter more feasible, robust, and reliable with high power density for an EV application. A comprehensive study of proposed steady-state operation, design, and simulation results is reported. A proof-of-concept hardware laboratory prototype rated at 1.5 kW is established and tested to validate the claims and proposed converter performance.

A Soft-Switched Single-Stage Single-Phase PFC Converter for Bidirectional Plug-In EV Charger

Space vector modulation (SVM) technique for current source converter (CSC) results in low-order non-characteristic 5th and 7th harmonics (HD 5–7 ) at low switching frequency (LSF) applications. Reduce HD 5–7 can be achieved by calculating the states' ON times to synthesize space vector (SV) instantaneously during rotation with a set of equations. Those equations calculate each state ON time in the mid-point of its existence. This paper investigates a SV sector and its cycles to analyze HD 5–7 results. Instantaneous presentation of SV is the main but not the only reason for reducing HD 5–7 . Symmetry assessment between active states ON times in each SV sector, beside the ratio between the actual SV cycle time and the one required to satisfy instantaneous SV presentation affect HD 5–7 in LSF-SVM-CSC.

The effect of states ON time calculations and states sequence in low order harmonics of space vector modulated current source converter

Renewable energy sources can help reduce many issues related to fuel consumption and environmental impact of diesel based electricity generation in autonomous power systems (mini-grids). However, the fluctuating nature of wind energy can make the power demanded from the diesel gen-sets and grid frequency vary more, increasing unit cycling and leading to power quality and maintenance problems. Sophisticated wind turbines (WTs) can minimize these issues but they are costly. This paper investigates the potential of inexpensive fixed-pitch type 1 WTs to assist with frequency regulation and power balancing in storage-less wind-diesel hybrid mini-grids.

https://ieeexplore.ieee.org/iel7/6495638/6505636/06505939.pdf

Luiz A. C. Lopes

Papers

An Accurate Loss Model of Single-Stage Single-Phase Isolated PFC Converter for Bidirectional Plug-in EV Charger

A Droop-Controlled Interlink Converter for a Dual DC Bus Nanogrid with Decentralized Control

A Soft-Switched Single-Stage Single-Phase PFC Converter for Bidirectional Plug-In EV Charger

The effect of states ON time calculations and states sequence in low order harmonics of space vector modulated current source converter

Fixed-pitch type 1 wind turbines with large droop slopes for diesel hybrid mini-grids