Primary-Side-Converter-Assisted Soft-Switching Scheme for an AC/AC Converter in a Cycloconverter-Type High-Frequency-Link Inverter

Abstract—

Emerging trends of high-power-density power-electronics interfaces for renewable- and alternative-energy sources have led to the need for high-frequency-inverter designs without compromising energy-conversion efficiency. In that context, a zero-voltage-switching (ZVS)-based scheme is described in this letter, for a cycloconverter-type high-frequency-link inverter, which is applicable for renewable- and alternative-energy sources as well as other commercial applications. The proposed scheme achieves the primary-side-converter-assisted switching of the ac/ac converter switches under ZVS condition. The modes of operation of the ac/ac converter are explained to outline the behavioral response. The results on the efficacy of the ZVS-based inverter and its performance show satisfactory performances.

Isolated Two-Transistor Zeta Converter With Reduced Transistor Voltage Stress

Abstract—

This brief introduces an isolated two-switch Zeta dc–dc converter, along with the steady-state analysis and experimentation. The high transistor voltage stress due to the ringing caused by the resonance of the transformer leakage inductance and the transistor output capacitance is a major drawback in the conventional isolated Zeta converter. With the incorporation of an additional transistor and two clamping diodes on the primary side of the transformer of the isolated Zeta converter, an isolated two-transistor Zeta converter is proposed. In the proposed converter, the voltage stress of both transistors is reduced to the dc input voltage VI. Experimental results from a 10-V/30-W 100-kHz laboratory prototype is presented to validate the theoretical analysis.
Index Terms—Clamping diodes, dc-dc converters, transformer leakage inductance, transistor output capacitance, two-transistor isolated Zeta converter, Zeta converter.

Feasibility Analysis of the Positioning of Superconducting Fault Current Limiters for the Smart Grid Application Using Simulink and SimPowerSystem

Abstract—

One of the most important topics regarding the application of superconducting fault current limiters (SFCL) for upcoming smart grid is related to its possible effect on the reduction of abnormal fault current and the suitable location in the micro grids. Due to the grid connection of the micro grids with the current power grids, excessive fault current is a serious problem to be solved for successful implementation of micro grids. However, a shortage of research concerning the location of SFCL in micro grid is felt. In this work, a resistive type SFCL model was implemented by integrating Simulink and SimPowerSystem blocks in Matlab. The designed SFCL model could be easily utilized for determining an impedance level of SFCL according to the fault-current-limitation requirements of various kinds of the smart grid system. In addition, typical smart grid model including generation, transmission and distribution network with dispersed energy resource was mod-eled to determine the location and the performance of the SFCL. As for a dispersed energy resource, 10 MVA wind farm was considered for the simulation. Three phase faults have been simulated at different locations in smart grid and the effect of the SFCL and its location on the wind farm fault current was evaluated. Consequently, the optimum arrangement of the SFCL location in Smart Grid with renewable resources has been proposed and its remarkable performance has been suggested.

Diagnosis of the Open-Circuit Fault in Three-Parallel Voltage-Source Converver for a High-Power Wind Turbine

Abstract—

 A fault detection method for the switch devices of three-parallel power converters in a wind turbine system is presented. The proposed method utilizes the measured 3-phase currents which were already used for controlling the converters. Additional current and voltage sensors are thus not necessary. Consequently, this particular feature potentially cuts costs to apply the detection algorithm. The 3-phase currents are transformed to a stationary reference frame. This reference frame possesses specific patterns in accordance to the conditions of the switch devices in the converter. Open faulty switches can be detected by analyzing the obtained pattern. The reliability of the proposed fault detection method was proven by simulation results.

Auto-tuned, Discrete PID Controller for DC-DC Converter for fast transient response

Abstract--

Ziegler-Nichols tuned PID controller’s performances usually are not acceptable for applications requiring precise control. In this paper an improved discrete auto-tuning PID scheme is developed for DC-DC converters where large load changes are expected or the need for fast response time. The algorithm developed in this paper is used for the tuning discrete PID controller to obtain its parameters with a minimum computing complexity and is applied to Synchronous buck converter to improve its performance. To improve the transient response and rise time of the Converter, the controller parameters are continuously modified based on the current process trend. For its implementation a synchronous buck converter is designed and its MATLAB/Simulink model with non-linear parameters is developed and considered. Also, the non-linear effects such as S/H, quantization, delay, and saturation are considered in the close loop model. The simulation results demonstrate the effectiveness of the developed algorithms.

A Phase Shifted Semi-Bridgeless Boost Power Factor Corrected Converter for Plug in Hybrid Electric Vehicle Battery Chargers

Abstract—

In this paper, a phase shifted semi-bridgeless boost power factor corrected converter is proposed for plug in
hybrid electric vehicle battery chargers. The converter features high efficiency at light loads and low lines, which is critical to minimize the charger size, charging time and the amount and cost of electricity drawn from the utility; the component count, which reduces the charger cost; and reduced EMI. The
converter is ideally suited for automotive level I residential charging applications.
A detailed converter description and steady state operation analysis of this converter is presented. Experimental results of\ a prototype boost converter, converting universal AC input voltage to 400 V DC at 3.4 kW are given and the results are compared to an interleaved boost converter to verify the proof of concept, and analytical work reported. The results show a power factor greater than 0.99 from 750 W to 3.4 kW, THD less than 5% from half load to full load and a peak efficiency of
98.6 % at 240 V input and 1000 W load.

A New High-Efficiency Single-Phase Transformerless PV Inverter Topology

Abstract—

There is a strong trend in the photovoltaic inverter
technology to use transformerless topologies in order to acquire higher efficiencies combining with very low ground leakage current.
In this paper, a new topology, based on the H-bridge with a new ac bypass circuit consisting of a diode rectifier and a switch with clamping to the dc midpoint, is proposed. The topology is simulated and experimentally validated, and a comparison with
other existing topologies is performed. High conversion efficiency and low leakage current are demonstrated.