Non-isolated high gain DC-DC converter by quadratic boost converter and voltage multiplier cell

AbstractA novel non-isolated DC-DC converter is proposed by combining quadratic boost converter with voltage multiplier cell. The proposed converter has low semiconductor device voltage stress and switch utilization factor is high. The superiority of the converter is voltage stress of the semiconductor devices depends on voltage multiplier (VM) cell. By increasing the VM cell the stresses across the devices reduce drastically. The proposed converter has same number of components compared to certain voltage lift converters taken for comparison. A detailed comparative study is made on the proposed converter with few voltage lift converters in the literature, conventional boost with VM cell and quadratic boost converter. A 40W prototype is constructed with 12V input voltage and 96V output voltage to verify the performance and validate the theoretical analysis of the proposed converter

Survey of DC-DC Non-Isolated Topologies for Unidirectional Power Flow in Fuel Cell Vehicles

The automobile companies are focusing on recent technologies such as growing Hydrogen (H2) and Fuel Cell (FC) Vehicular Power Train (VPT) to improve the Tank-To-Wheel (TTW) efficiency. Benefits, the lower cost, `Eco\u27 friendly, zero-emission and high-power capacity, etc. In the power train of fuel cell vehicles, the DC-DC power converters play a vital role to boost the fuel cell stack voltage. Hence, satisfy the demand of the motor and transmission in the vehicles. Several DC-DC converter topologies have proposed for various vehicular applications like fuel cell, battery, and renewable energy fed hybrid vehicles etc. Most cases, the DC-DC power converters are viable and cost-effective solutions for FC-VPT with reduced size and increased efficiency. This article describes the state-of-the-art in unidirectional non-isolated DC-DC Multistage Power Converter (MPC) topologies for FC-VPT application. The paper presented the comprehensive review, comparison of different topologies and stated the suitability for different vehicular applications. This article also discusses the DC-DC MPC applications more specific to the power train of a small vehicle to large vehicles (bus, trucks etc.). Further, the advantages and disadvantages pointed out with the prominent features for converters. Finally, the classification of the DC-DC converters, its challenges, and applications for FC technology is presented in the review article as state-of-the-art in research

Two new families of high-gain DC-DC power electronic converters for DC-microgrids

Distributing the electric power in dc form is an appealing solution in many applications such as telecommunications, data centers, commercial buildings, and microgrids. A high gain dc-dc power electronic converter can be used to individually link low-voltage elements such as solar panels, fuel cells, and batteries to the dc voltage bus which is usually 400 volts. This way, it is not required to put such elements in a series string to build up their voltages. Consequently, each element can function at it optimal operating point regardless of the other elements in the system. In this dissertation, first a comparative study of dc microgrid architectures and their advantages over their ac counterparts is presented. Voltage level selection of dc distribution systems is discussed from the cost, reliability, efficiency, and safety standpoints. Next, a new family of non-isolated high-voltage-gain dc-dc power electronic converters with unidirectional power flow is introduced. This family of converters benefits from a low voltage stress across its switches. The proposed topologies are versatile as they can be utilized as single-input or double-input power converters. In either case, they draw continuous currents from their sources. Lastly, a bidirectional high-voltage-gain dc-dc power electronic converter is proposed. This converter is comprised of a bidirectional boost converter which feeds a switched-capacitor architecture. The switched-capacitor stage suggested here has several advantages over the existing approaches. For example, it benefits from a higher voltage gain while it uses less number of capacitors. The proposed converters are highly efficient and modular. The operating modes, dc voltage gain, and design procedure for each converter are discussed in details. Hardware prototypes have been developed in the lab. The results obtained from the hardware agree with those of the simulation models. --Abstract, page iv

A Comprehensive Review of DC-DC Converters for EV Applications

DC-DC converters in Electric vehicles (EVs) have the role of interfacing power sources to the DC-link and the DC-link to the required voltage levels for usage of different systems in EVs like DC drive, electric traction, entertainment, safety and etc. Improvement of gain and performance in these converters has a huge impact on the overall performance and future of EVs. So, different configurations have been suggested by many researches. In this paper, bidirectional DC-DC converters (BDCs) are divided into four categories as isolated-soft, isolated-hard, non-isolated-soft and non-isolated-hard depending on the isolation and type of switching. Moreover, the control strategies, comparative factors, selection for a specific application and recent trends are reviewed completely. As a matter of fact, over than 200 papers have been categorized and considered to help the researchers who work on BDCs for EV application

Boost Matrix Converters in Clean Energy Systems

This dissertation describes an investigation of novel power electronic converters, based on the ultra-sparse matrix topology and characterized by the minimum number of semiconductor switches. The Z-source, Quasi Z-source, Series Z-source and Switched-inductor Z-source networks were originally proposed for boosting the output voltage of power electronic inverters. These ideas were extended here on three-phase to three-phase and three-phase to single-phase indirect matrix converters. For the three-phase to three-phase matrix converters, the Z-source networks are placed between the three-switch input rectifier stage and the output six-switch inverter stage. A brief shoot-through state produces the voltage boost. An optimal pulse width modulation technique was developed to achieve high boosting capability and minimum switching losses in the converter. For the three-phase to single-phase matrix converters, those networks are placed similarly. For control purposes, a new modulation technique has been developed. As an example application, the proposed converters constitute a viable alternative to the existing solutions in residential wind-energy systems, where a low-voltage variable-speed generator feeds power to the higher-voltage fixed-frequency grid.Comprehensive analytical derivations and simulation results were carried out to investigate the operation of the proposed converters. Performance of the proposed converters was then compared between each other as well as with conventional converters. The operation of the converters was experimentally validated using a laboratory prototype

A wide input-voltage range quasi-Z source boost DC-DC converter with high voltage-gain for fuel cell vehicles

A quasi-Z-source Boost DC-DC converter which uses a switched-capacitor is proposed for fuel cell vehicles. The topology can obtain a high voltage gain with a wide input-voltage range, and requires only a low voltage stress across each of the components. The performance of the proposed converter is compared with other converters which use Z-source networks. A scaled-down 400V/400W prototype is developed to validate the proposed technology. The respective variation in the output voltage is avoided when the wide variation in the input voltage happens, due to the PI controller in the voltage loop, and a maximum efficiency of 95.13% is measured

Design and implementation a novel single switch high gain DC-DC converter based on coupled inductor with low-ripple input current

A novel high-gain and high-efficiency direct current to direct current (DC-DC) converter is introduced in this paper. The presented converter is suitable for low-voltage renewable energy resources such as photovoltaic (PV) and fuel cell (FC). The existence of series inductance with the input source ensures continuous and low-ramp input current, which is important for extracting maximum power from resources. Using coupled inductor technology and an intermediate capacitor in the suggested converter leads to a high gain voltage. In the presented topology for recovering energy from the leakage inductor, reducing voltage stress on the power switch, and so decreasing overall converter losses, a passive clamp circuit is used. The suitable operation range of duty cycle in the converter, besides the leakage inductor, decreases the problem of reverse recovery in diodes. The low value of the leakage inductor and the low volume and cost of the proposed converter are due to the low turn ratio of the coupled inductor. Details of the operation principles of the proposed converter have been discussed in this paper. The presented simulation and laboratory prototype results verify the theoretical analysis and performance of the suggested topology

A Family of Interleaved High Step-Up DC-DC Converters by Integrating a Voltage Multiplier and an Active Clamp Circuits

A family of interleaved current-fed high step-up dc-dc converters are introduced and analyzed here by combining a voltage multiplier (VM) and an active clamp circuit for high-voltage high-power applications. Low input currents and output voltages ripples values and high voltage-gains characteristics of these converters make them suitable for lots of dc-dc applications. All power devices operate entirely under soft switching conditions, even when wide load and input voltage variations are applied. Thus, they can be designed at high switching frequencies to reduce passive components sizes to achieve high-power density, one of the main targets of the power electronics researches. Also, their input and output ports common ground simplifies the gate-drives and control circuits. To verify the given analyses and simulations, a 120-320 V to 1 kV, 50-1300 W three-stage two-leg prototype converter has been implemented at 100 kHz. Based on the experimental results, maximum efficiency of 96.5% is achieved.Comment: 14 pages, 15 figure

Large step down voltage converters for desalination

One percent of the world's drinking water is currently desalinated, and this will have to increase to 14% by 2025. Desalination is energy intensive, having significant commercial and ecological implications. One of the most promising methods of desalination is capacitive deionisation which only uses 1kWh/m3 but requires a voltage of less than 1.8V at currents of up to 1000A This thesis produced hardware capable of creating 550A at a voltage of 1.8V, giving over a 1kW power rating, with an input voltage of 340V dc. The converter designed was a bidirectional asymmetrical half-bridge flyback converter allowing for isolation at these high step down ratios. The converter was used to charge a bank of 17,000F supercapacitors from 0V to 1.8V, with an initial charging step down ratio in excess of 340:1 falling to 190:1 as the load charged. A novel Asymmetrical Half-Bridge Coupled-Inductor Buck converter is presented as the ideal solution for large step-down ratios with analysis comparing the ability to efficiently step down a voltage with other common converters, the buck and flyback converters. A comparison between a single-ended coupled-inductor buck converter employing a buck-boost voltage clamp and the novel asymmetrical half-bridge coupled-inductor buck converter circuit shows that the asymmetrical half-bridge converter is a more efficient circuit as leakage energy is recovered; the switch voltages are clamped to within the dc voltage rating of the bridge and the control strategy is simple. Passive and active snubbers are reviewed for efficiency, switch ratings and management of the effects of leakage inductance and compared against the novel designs presented. In the desalination application isolation is required so the flyback circuit is used. An isolated three switch bidirectional converter is constructed using silicon carbide MOSFETs and diodes switching at 40kHz. The converter uses novel current measuring techniques, an on-board microprocessor and closed loop control designed into the final DC-DC converter.One percent of the world's drinking water is currently desalinated, and this will have to increase to 14% by 2025. Desalination is energy intensive, having significant commercial and ecological implications. One of the most promising methods of desalination is capacitive deionisation which only uses 1kWh/m3 but requires a voltage of less than 1.8V at currents of up to 1000A This thesis produced hardware capable of creating 550A at a voltage of 1.8V, giving over a 1kW power rating, with an input voltage of 340V dc. The converter designed was a bidirectional asymmetrical half-bridge flyback converter allowing for isolation at these high step down ratios. The converter was used to charge a bank of 17,000F supercapacitors from 0V to 1.8V, with an initial charging step down ratio in excess of 340:1 falling to 190:1 as the load charged. A novel Asymmetrical Half-Bridge Coupled-Inductor Buck converter is presented as the ideal solution for large step-down ratios with analysis comparing the ability to efficiently step down a voltage with other common converters, the buck and flyback converters. A comparison between a single-ended coupled-inductor buck converter employing a buck-boost voltage clamp and the novel asymmetrical half-bridge coupled-inductor buck converter circuit shows that the asymmetrical half-bridge converter is a more efficient circuit as leakage energy is recovered; the switch voltages are clamped to within the dc voltage rating of the bridge and the control strategy is simple. Passive and active snubbers are reviewed for efficiency, switch ratings and management of the effects of leakage inductance and compared against the novel designs presented. In the desalination application isolation is required so the flyback circuit is used. An isolated three switch bidirectional converter is constructed using silicon carbide MOSFETs and diodes switching at 40kHz. The converter uses novel current measuring techniques, an on-board microprocessor and closed loop control designed into the final DC-DC converter