A New Soft-Switched High Step-Up Trans-Inverse DC/DC Converter Based on Built-In Transformer

This article proposes a new Zero-Voltage Switching (ZVS) high step-up DC/DC converter based on a built-in transformer for renewable energy applications. The proposed topology utilizes a Three-Winding Built-In Transformer (TWBT) to increase the voltage gain, but unlike most coupled-inductor-based DC-DC converters, high output voltages can be obtained under a lower magnetic turns ratio. In this circuit, with the help of a regenerative active clamp circuit, the energy of the leakage inductor from the TWBT is absorbed and transferred to the output, therefore, the ZVS conditions at turn-on time are achieved for switches. The voltage stresses across the switches of the proposed topology are limited, and the diodes reverse-recovery issue are eliminated. Due to the low input current ripple, the suggested topology can be used for renewable energy sources. Furthermore, because of the low number of components along with the soft-switching operation, the proposed circuit can offer enough high efficiency. The operational principle, steady-state analysis, and characteristics of the proposed converter are provided. Finally, a 200 W prototype with 25 V input and 400 V output voltage is built to validate the analytical results

Active Neutral Point-Clamped Five-Level Inverter With Single-Stage Dynamic Voltage Boosting Capability

The circuit performance of conventional active neutral point-clamped (ANPC) inverter is widely accepted in many renewable energy-based applications like photovoltaic (PV) or electric vehicle grid-connected systems. This is mainly because of its excellent characteristics in terms of voltage/current stress profile of the switches, bidirectional power flow capability, and efficient operation. Nonetheless, due to its half-dc link voltage utilization in the ac output voltage, another power processing stage with additional active and passive elements is required to make its output voltage compatible with the grid when low and wide varying input dc source is available. In this paper, a novel ANPC-based five-level (ANPC5L) inverter with a single-stage boost-integrated circuit design is presented. The proposed topology is able to make the peak output voltage of the conventional ANPC5L inverter followed by a front-end bidirectional boost converter double using the same number of power switches but with less total standing voltage across semiconductors. The working principles of the proposed topology is discussed. Experimental results obtained from 1.3 kW laboratory-built prototype under the grid-connected condition are also given to support the discussion

Impedance-source network power converters

Thesis by publication.Bibliography: pages 175-186.1. Introduction -- 2. Improved modulation techniques -- 3. Quasi Z-source push-pull dc-dc converter -- 4. Y-source impedance network -- 5. Analysis of leakage inductances on impedance source networks -- 6. A distributed DC power system using quasi-Z source dc-dc converter -- 7. Conclusions.The research described in this thesis covers the analysis and design of impedance-source networks for a wide range of electric power conversion applications (dc-dc, dc-ac, ac-dc, ac-ac). Variance impedance networks, circuit topologies and modulation techniques were analysed, designed and tested in the laboratory to improve performance (efficiency, reliability and power density) of the converter. To achieve this, three distinct approaches were taken in this research, which include: i) investigate and implement a new modulation technique, ii) retrofit existing topologies to get an improved hybrid topology, and iii) investigate a novel converter topology with desired performance.Mode of access: World wide web1 online resource (xiv, 186 pages) illustrations (some colour

SP0123 How to Evaluate CPPD Using Ultrasound

© 1986-2012 IEEE. This paper introduces a new single-switch nonisolated dc-dc converter with very high voltage gain and reduced semiconductor voltage stress. The converter utilizes an integrated autotransformer and a coupled inductor on the same core in order to achieve a very high voltage gain without using extreme duty cycle. Furthermore, a passive lossless clamp circuit recycles the leakage energy of the coupled magnetics and alleviates the voltage spikes across the main switch. This feature along with low stress on the switching device enables the designer to use a low voltage and low RDS-on MOSFET, which reduces cost, as well as conduction and turn on losses of the switch. The principle of operation, theoretical analysis, and comparison supported by some key simulation and experimental results of a 500 W prototype are presented

Three-phase transformerless grid connected Quasi Z-Source Inverter for solar photovoltaic systems with minimal leakage current

We present the design of 3-phase transformerless grid connected Quasi Z-Source Inverter with minimal leakage current, suitable for application in solar photovoltaic systems. A modified space vector pulse width modulation technique with a reduced number of commutations per sector was used to minimize the leakage current without adding extra circuitry (filters and/or leakage current isolation/bypass circuits) in a transformerless Quasi Z-Source Inverter. Theoretical analysis of the proposed system is presented in detail and verified using Matlab Simulink®.6 page(s

Circuit-Based Rainflow Counting Algorithm in Application of Power Device Lifetime Estimation

The software-assisted reliability assessment of power electronic converters is increasingly important due to its multi-domain nature and extensive parametric calculations. The rainflow counting algorithm is gaining popularity for its low relative error in device lifetime estimation. Nevertheless, the offline operation of the algorithm prevents most simulation software packages considering other parameters for the device under study, such as aging and the current state of health in the estimation, as it requires a complete loading profile to run recursive comparison. This also brings difficulties in realization in circuit simulators such as SPICE. To tackle the issue, an in-the-loop circuit-based rainflow counting algorithm is proposed in this paper, and applied to estimate the consumed lifetime of the MOSFET in a boost converter for illustration. Instantaneous electrical and thermal performances, and the accumulated stress of the device can be monitored. Not only does this assist in evaluating the state of health of a device, but also allows the possibility of integrating the aging into the lifetime evaluation. The method follows the four-point rainflow counting algorithms, which continuously compares three adjacent temperature fluctuations ΔTj to select full cycles for two rounds, and the remaining cycles are counted as half cycles. To validate the performance, a comparative analysis in terms of counting accuracy and simulation speed was performed alongside the proposed method, MATLAB® and also with a well-accepted half-cycle counting method. Reported results show that the proposed method has an improved counting accuracy compared to the half-cycle counting from 24% to 3.5% on average under different load stresses and length conditions. The accuracy can be effectively improved by a further 1.3–2% by adding an extra comparison round