Topology (electrical circuits)

About: Topology (electrical circuits) is a research topic. Over the lifetime, 33316 publications have been published within this topic receiving 397651 citations. The topic is also known as: topology.

A novel single-phase power factor correction scheme

Abstract: A single-phase power factor correction scheme is proposed based on the power flow analysis. It is found that the conventional power factor correction (PFC) circuit must be designed to handle the rated power, although its purpose is only for power factor correction. With the proposed scheme, the PFC circuit is in parallel with the major power flow path, thus reducing its size and weight compared to a conventional two-cascade-stage scheme. A prototype circuit is built and tested to verify this concept. >

Transformerless Split-Inductor Neutral Point Clamped Three-Level PV Grid-Connected Inverter

Abstract: Characterized by low leakage current and low voltage stress of the power device, a neutral point clamped three-level inverter (NPCTLI) is suitable for a transformerless photovoltaic (PV) grid-connected system. Unfortunately, the shoot-through problem of bridge legs still exists in an NPCTLI, so its operation reliability is degraded. An improved three-level grid-connected inverter is proposed based on the NPCTLI and the dual-buck half-bridge inverter (DBHBI), and which avoids the shoot-through problem. The proposed topology guarantees no switching-frequency common-mode voltage and no shoot-through risk. Furthermore, the freewheeling diode of bridge legs of the DBHBI can be removed taking into consideration the unity power factor of grid current, and a straightforward topology is thus derived. The new topology is referred to as split-inductor NPCTLI (SI-NPCTLI). The operation mode, common-mode characteristic, and control strategy are analyzed. Finally, both the simulation and the experimental results of a 1-kW SI-NPCTLI prototype verify the analysis.

Nonlinear programming without computation

Abstract: Using the Kuhn-Tucker conditions from mathematical programming theory, a canonical nonlinear programming circuit for simulating general nonlinear programming problems has been developed. This circuit is canonical in the sense that its topology remains unchanged and that it requires only a minimum number of 2-terminal nonlinear circuit elements. Rather than solving the problem by iteration using a digital computer, we obtain the answer by setting up the associated nonlinear programming circuit and measuring the node voltages. In other words, the nonlinear programming circuit is simply a special purpose analog computer containing a repertoire of nonlinear function building blocks. To demonstrate the feasibility and advantage of this approach, several circuits have been built and measured. In all cases, the answers are obtained almost instantaneously in real time and are accurate to within 3 percent of the exact answers.

A New Nine-Level Active NPC (ANPC) Converter for Grid Connection of Large Wind Turbines for Distributed Generation

Abstract: Wind power is one of the most promising emerging renewable energy technologies for distributed generation (DG). In this paper, a new nine-level active neutral-point-clamped (9L ANPC) converter is proposed for the grid connection of large wind turbines (WTs) to improve the waveform quality of the converter output voltage and current. Therefore, the bulky passive grid filters can be reduced or even removed. The topology, operating principles, control schemes, and main features, as well as semiconductor device selection of the proposed converter are presented in detail. The floating capacitor voltage control based on redundant switching states and capacitor prioritization is detailed. A comparison between the new topology and other existing 9L topologies is presented to illustrate the characteristics and performance of the new converter. The proposed 9L ANPC converter is studied in the case of the grid connection of a 6-MW WT without using passive grid filters in DG systems. Simulation and experiment results are presented to validate the proposed converter topology and control schemes. The proper operation and the compliance to the harmonic limit standards of the filterless grid-connected WT system are verified by simulation results.

Protection cycles in mesh WDM networks

Abstract: A fault recovery system that is fast and reliable is essential to today's networks, as it can be used to minimize the impact of the fault on the operation of the network and the services it provides. This paper proposes a methodology for performing automatic protection switching (APS) in optical networks with arbitrary mesh topologies in order to protect the network from fiber link failures. All fiber links interconnecting the optical switches are assumed to be bidirectional. In the scenario considered, the layout of the protection fibers and the setup of the protection switches is implemented in nonreal time, during the setup of the network. When a fiber link fails, the connections that use that link are automatically restored and their signals are routed to their original destination using the protection fibers and protection switches. The protection process proposed is fast, distributed, and autonomous. It restores the network in real time, without relying on a central manager or a centralized database. It is also independent of the topology and the connection state of the network at the time of the failure.