Hybrid three-phase rectifiers with active power factor correction: a systematic review

The hybrid three-phase rectifiers (HTR) consist of parallel associations of two rectifiers (rectifier 1 and rectifier 2), each one of them with a distinct operation, while the sum of their input currents forms a sinusoidal or multilevel waveform. In general, the rectifier 1 is a GRAETZ (full bridge) (can be combined with a BOOST converter) and the rectifier 2 combined with a DC-DC converter. In this HTR contest, this paper is intended to answer some important questions about those hybrid rectifiers. To obtain the correct answers, the study is conducted as an analysis of a systematic literature review. Thus, a search was carried out in the databases, mostly IEEE and IET, and 34 papers were selected as the best corresponding to the HTR thematic. It is observed that the preferred form of power distribution in a unidirectional hybrid three-phase rectifiers (UHTR) is 〖55%P〗_o (rectifier 1) and 〖45%P〗_o (rectifier 2). For the bidirectional hybrid three-phase rectifiers (BHTR) the rectifier 1 preferably takes 〖90% of P〗_o and 〖10% of P〗_o are processed by rectifier 2. It is also observed that the UHTR that employ the single-ended primary-inductor converter (SEPIC) or VIENNA converter topologies in their rectifier 2, can present sinusoidal input currents with low total harmonic distortion (THD) and high Power Factor (PF), even succeeding to comply with the international standards. The same can be said about the rectifier that employs a pulse-width (PWM) converter of BOOST topology in rectifier 2. In short, the HTR are interesting because they allow to use the GRAETZ full bridge topology in rectifier 1, thus taking advantage of its characteristics, being simple, robust and reliable. At the same time, the advantages of rectifier 2, i.e., high PF and low THD are well used. In addition, this article also points out the future direction of research that is still unexplored in the literature, thus giving opportunities for future innovation

Design of High-Gain DC-DC Converters for High-Power PV Applications

Renewable energy sources are penetrating the market in an ever increasing rate, especially in terms of Wind and Solar energies, with the latter being more suitable for the GCC region. Typically, Photovoltaic (PV) strings’ output voltage is limited to ~ 1500 V due to safety constraints, and thus requires boosting to higher DC levels (non-isolated step-up DC-DC transformer) suitable for High-Voltage DC (HVDC) and AC grid applications in order to provide the required DC-Link voltage level. Nevertheless, conventional non-isolated DC-DC converters provide a limited practical gain due to their parasitic elements. Other options include isolated DC-DC converters that utilize costly high-frequency transformers with limited power capability. Moreover, the isolation requirements of transformers in HVDC significantly increase the footprint of the converters. High-frequency transformers for high-power applications are hard to design and are usually associated with higher losses. Alternatively, connecting conventional DC-DC converters in different combinations can provide higher gains to the required levels, while maintaining the high efficiency requirements. This thesis proposes the cascade and/or series connection of DC-DC modules as a solution to the high-conversion ratio requirement, based on Cuk and Single-Ended Primary Inductor Converter (SEPIC) topologies, whose continuous input current is suitable for PV applications, and reduces the bulky capacitor filters at the input side. Detailed theoretical models of the proposed topologies are first derived, then their trends are practically verified by low power prototypes. Sensitivity analysis is also performed to assess the effect of small variations to the parasitic inductors’ resistances on the overall system gain, where the input inductor is found to have a considerable effect, especially at higher duty ratios (i.e. higher gains). High-power applications’ scenarios with their considerations are simulated to compare the different topologies and the results show a comparable efficiency of the proposed converters for a 1 –MW application with efficiencies higher than 90%

Performance numerical evaluation of modified single-ended primary-inductor converter for photovoltaic systems

Single-ended primary-inductor converter (SEPIC) was considered a good alternative to a DC-DC converter for photovoltaic (PV) systems. The SEPIC converter can operate with an input voltage greater or less than the regulated output voltage, or as a step-up or step-down. As a step-up converter, SEPIC boosts PV voltage to specific levels. However, gain limitation and voltage stress continue to reduce the efficiency of conventional SEPIC converters. Because of this, researchers created a modified SEPIC converter to improve performance. In this paper, six modified SEPIC converters were compared and evaluated. To compare fairly, all modified SEPIC converters are non-isolated and use a single switch. Power simulator (PSIM) software was used to simulate each converter with a BISOL BMO-250 PV module and maximum power point tracking (MPPT) P&O controller. The converter with the highest static voltage gain and lowest duty cycle has been identified. It results in up to ten times voltage increment with a 0.8-duty ratio. All topologies have the same voltage stress, with maximum and minimum values of 30.1 V and 29.5 V, respectively. On the other hand, each topology produces different average efficiencies, with the highest and lowest efficiency at 99.5% and 97.2%, respectively

Power Converters in Power Electronics

In recent years, power converters have played an important role in power electronics technology for different applications, such as renewable energy systems, electric vehicles, pulsed power generation, and biomedical sciences. Power converters, in the realm of power electronics, are becoming essential for generating electrical power energy in various ways. This Special Issue focuses on the development of novel power converter topologies in power electronics. The topics of interest include, but are not limited to: Z-source converters; multilevel power converter topologies; switched-capacitor-based power converters; power converters for battery management systems; power converters in wireless power transfer techniques; the reliability of power conversion systems; and modulation techniques for advanced power converters

High step up DC-DC converter topology for PV systems and electric vehicles

This thesis presents new high step-up DC-DC converters for photovoltaic and electric vehicle applications. An asymmetric flyback-forward DC-DC converter is proposed for the PV system controlled by the MPPT algorithm. The second converter is a modular switched-capacitor DC-DC converter, it has the capability to operate with transistor and capacitor open-circuit faults in every module. The results from simulations and tests of the asymmetric DC-DC converters have suggested that the proposed converter has a 5% to 10% voltage gain ratio increased to the symmetric structures among 100W – 300W power (such as [3]) range while maintaining efficiency of 89%-93% when input voltage is in the range of 25 – 30 V. they also indicated that the softswitching technique has been achieved, which significantly reduce the power loss by 1.7%, which exceeds the same topology of the proposed converter without the softswitching technique. Moreover, the converters can maintain rated outputs under main transistor open circuit fault situation or capacitor open circuit faults. The simulation and test results of the proposed modularized switched-capacitor DC-DC converters indicate that the proposed converter has the potential of extension, it can be embedded with infinite module in simulation results, however, during experiment. The sign open circuit fault to the transistors and capacitors would have low impact to the proposed converters, only the current ripple on the input source would increase around 25% for 4-module switched-capacitor DC-DC converters. The developed converters can be applied to many applications where DC-DC voltage conversion is alighted. In addition to PVs and EVs. Since they can ride through some electrical faults in the devices, the developed converter will have economic implications to improve the system efficiency and reliability

Analysis of a new family of DC-DC converters with input-parallel output-series structure

There is an increasing trend of development and installation of switching power supplies due to their highly efficient power conversion, fast power control and high quality power conditioning for applications such as renewable energy integration and energy storage management systems. In most of these applications, high voltage conversion ratio is required. However, basic switching converters have limited voltage conversion ratio. There has been much research into development of high gain power converters. While most of the reported topologies focus on high gain and high efficiency, in this thesis, the input and output ripple currents and reliability are also considered to derive a new converter structure suitable for high step-up voltage conversion applications. High ripple currents and voltages at the input and output of dc-dc converters are not desirable because they may affect the operation of the dc source or the load. A number of converters operating in an interleaved manner can reduce these ripples. This thesis proposes a dc/dc switching converter structure which is capable of reducing the ripple problem through interleaved action, in addition to high gain and high efficiency voltage conversion. The thesis analyses the proposed converter structure through a dual buck-boost converter topology. The structure allows different converter topologies and combinations of them for different applications to be configured. The study begins with a motivation and a literature review of dc/dc converters. The new family of high step-up converters is introduced with an interleaved buck-boost as an example, followed by small-signal analysis. Experimental verifications, conclusions and future work are discussed

Analysis of a new family of DC-DC converters with input-parallel output-series structure

There is an increasing trend of development and installation of switching power supplies due to their highly efficient power conversion, fast power control and high quality power conditioning for applications such as renewable energy integration and energy storage management systems. In most of these applications, high voltage conversion ratio is required. However, basic switching converters have limited voltage conversion ratio. There has been much research into development of high gain power converters. While most of the reported topologies focus on high gain and high efficiency, in this thesis, the input and output ripple currents and reliability are also considered to derive a new converter structure suitable for high step-up voltage conversion applications. High ripple currents and voltages at the input and output of dc-dc converters are not desirable because they may affect the operation of the dc source or the load. A number of converters operating in an interleaved manner can reduce these ripples. This thesis proposes a dc/dc switching converter structure which is capable of reducing the ripple problem through interleaved action, in addition to high gain and high efficiency voltage conversion. The thesis analyses the proposed converter structure through a dual buck-boost converter topology. The structure allows different converter topologies and combinations of them for different applications to be configured. The study begins with a motivation and a literature review of dc/dc converters. The new family of high step-up converters is introduced with an interleaved buck-boost as an example, followed by small-signal analysis. Experimental verifications, conclusions and future work are discussed

High_Voltage_DC_to_DC_Converter

The purpose of this project was to create a high voltage DC-DC converter for use in inverter applications. Extensive background research was conducted to evaluate existing inverter device functionality. Multiple prototypes were constructed to characterize losses and investigate ways to maximize efficiency. Testing of the final prototype included load testing, thermal characterization, efficiency evaluation, and noise level capture, with mixed results. Further work is required to provide closed loop control, safety shut off and low battery warnings

Survey on Photo-Voltaic Powered Interleaved Converter System

Renewable energy is the best solution to meet the growing demand for energy in the country. The solar energy is considered as the most promising energy by the researchers due to its abundant availability, eco-friendly nature, long lasting nature, wide range of application and above all it is a maintenance free system. The energy absorbed by the earth can satisfy 15000 times of today’s total energy demand and its hundred times more than that our conventional energy like coal and other fossil fuels. Though, there are overwhelming advantages in solar energy, It has few drawbacks as well such as its low conversion ratio, inconsistent supply of energy due to variation in the sun light, less efficiency due to ripples in the converter, time dependent and, above all, high capitation cost. These aforementioned flaws have been addressed by the researchers in order to extract maximum energy and attain hundred percentage benefits of this heavenly resource. So, this chapter presents a comprehensive investigation based on photo voltaic (PV) system requirements with the following constraints such as system efficiency, system gain, dynamic response, switching losses are investigated. The overview exhibits and identifies the requirements of a best PV power generation system