Midpoint Connection Research Articles

Double Fault-Tolerant LLC Resonant Converter With Reconfiguration Method

A fault-tolerant converter is widely used in high-reliability applications. To satisfy the high-reliability requirements, fault tolerance is an essential feature and can be achieved by redundant converters. However, a large number of redundant converters degrade the overall power density and cost. This paper proposes a novel fault-tolerant <i>LLC</i> converter, which can reduce the number of redundant converters. Its structure is based on the input-parallel, output-series two half-bridge <i>LLC</i> converters and a midpoint connection on the secondary side. The proposed converter can withstand double short-circuit faults (SCFs) by utilizing only two converters instead of three converters. The redundant converter is used to achieve a single fault-tolerant capability against an SCF. When a second SCF occurs in the switch, the proposed converter is reconfigured to regulate the output voltage without additional semiconductor components. By analyzing the proposed converter, it is demonstrated that the proposed converter achieves high power density and low cost without degradation of efficiency. In addition, it can be easily extended to have multiple fault-tolerant capabilities. Finally, the performance and feasibility of the proposed converter were confirmed with a 100 V&#x002F;12 A 1200 W prototype.

Analysis of a Novel Four Level Flying Capacitor H – Bridge Converter

In this paper, a novel four-level flying capacitor inverter and its comparison with the conventional flying capacitor topology in terms of THD analysis are proposed. This new topology have some advantages over conventional one as following: The blocking voltages are the same for all switches used in the configuration, there is no need for capacitor midpoint connection and this eliminates low frequency current which circulate in dc-link capacitors, and the number of flying capacitor is reduced as compared with conventional form of it. The operation of the topology, modulation strategy, simulation results, and THD analysis for the output waveforms are presented in this paper.Article History: Received: 17th July 2017; Received: October 14th 2017; Accepted: Januari 18th 2018; Available onlineHow to Cite This Article: Gülpınar, F., Sarı, F., and Uzun, Y. (2017) Analysis of a Novel Four Level Flying Capacitor H – Bridge Converter. International Journal of Renewable Energy Development, 7(1), 71-75.https://doi.org/10.14710/ijred.7.1.71-75

Single-phase Active Power Filters With Reduced Number Of Power Switches And Optimum Voltage Control Angle

&#x0D; This paper proposes some topologies of universal active power filter for single-phase applications with reduced number of components. Some configurations are proposed: two with both series and parallel converters connected in half-bridge, sharing the same d.c.-bus mid-point connection; and the others with the series and parallel converters sharing one leg. It will be demonstrated the existence of a coupling law between the two converters (Se and Sh) related to the voltage capabilities. All configurations compensate current and voltage harmonic and provide power factor control close to unit. Comparisons between the structures are made and the steady-state analysis are also presented to demonstrate that it is possible to obtain an optimum voltage angle in order to reduced the amplitudes of the converters’ currents and, consequently, the total losses of the systems. Simulated and experimental results validate the theoretical considerations.&#x0D;

System reconfiguration under open-switch faults in a doubly fed induction machine

The aim of this study is to present system reconfiguration for a doubly fed induction machine (DFIM) after an open-switch fault is detected in its back-to-back converters. The open-switch fault and its detection for the scheme are discussed first. System reconfiguration is applied to operate the DFIM after the fault is detected. A four-switch converter topology with dc-link midpoint connection is selected to reconfigure the system. An existing pulse-width modulation method is investigated and applied to reconfigure the system, but uncontrollable capacitor voltage drift occurs. This study proposes a technique to solve the drift problem and also improve the quality of the dc-link voltage. Its effectiveness is substantiated by both simulation and experiment.

Reduced Switch-Count Six-Phase AC Motor Drive Systems Without Input Reactor

In this paper, two reduced switch-count six-phase ac motor drives are investigated. The first configuration considered has six legs (configuration 6L), and the second one has five legs (configuration 5L) and uses the capacitor dc-link midpoint connection. Both configurations operate without input reactors and provide both bidirectional power flow and power-factor control. Both 60 and 30 six-phase induction-machine windings are employed. Operating principles and control strategies for the topologies are presented. The proposed configurations are compared with the full-bridge (nine legs) and the half-bridge (six legs) topologies, which use the capacitor dc-link midpoint connection. These drive systems are suitable for applications where the size of the system is a critical factor. Experimental and simulation results are presented.

Pixy Stix Segments and the Midpoint Connection

The NCTM's Curriculum and Evaluation Standards for School Mathematics (1989) offers a vision of mathematically empowered students embarking on exciting flights of discovery. This vision challenges teachers to look for ways to incorporate problem solving, cooperative learning, mathematical connections, reasoning, communication skills, and proofs into lesson plans. The Pixy Stix activities described in this article are not quite as magical as Peter Pan and Tinkerbell's prescription of sprinkling pixie dust over children who want to fly, but they do embody all the attributes mentioned above and may enable your high school geometry students to take off in some surprising directions.