In this article a new Transformer and Switched Capacitor-based Boost Converter (T & SC-BC) is proposed for high-voltage/low-current renewable energy applications. The proposed T & SC-BC is an ...original extension for DC-DC boost converter which is designed by utilizing a transformer and switched capacitor (T & SC). Photovoltaic (PV) energy is a fast emergent segment among the renewable energy systems. The proposed T & SC-BC combines the features of the conventional boost converter and T & SC to achieve a high voltage conversion ratio. A Maximum Power Point Tracking (MPPT) controller is compulsory and necessary in a PV system to extract maximum power. Thus, a photovoltaic MPPT control mechanism also articulated for the proposed T & SC-BC. The voltage conversion ratio (Vo/Vin) of proposed converter is (1 + k)/(1 − D) where, k is the turns ratio of the transformer and D is the duty cycle (thus, the converter provides 9.26, 13.88, 50/3 voltage conversion ratios at 78.4 duty cycle with k = 1, 2, 2.6, respectively). The conspicuous features of proposed T & SC-BC are: (i) a high voltage conversion ratio (Vo/Vin); (ii) continuous input current (Iin); (iii) single switch topology; (iv) single input source; (v) low drain to source voltage (VDS) rating of control switch; (vi) a single inductor and a single untapped transformer are used. Moreover, the proposed T & SC-BC topology was compared with recently addressed DC-DC converters in terms of number of components, cost, voltage conversion ratio, ripples, efficiency and power range. Simulation and experimental results are provided which validate the functionality, design and concept of the proposed approach.
The solar PV based power generation systems are growing faster due to the depletion of fossil fuels and environmental concerns. Combining PV panels and energy buffers such as battery through ...multi-port converter is one of the viable solutions to deal with the intermittency of PV power. The goal of this paper is to design and analyze the proposed triple port DC-DC buck-boost converter for high step-up/step-down applications. It has two unidirectional ports (port-1 and port-3) and one bi-directional port (port-2) for harnessing photovoltaic energy and charging the battery. At port-1, the combined structure of buck and buck-boost converter is used with a particular arrangement of switches and inductors. The step-up/step-down voltage conversion ratio is higher than the conventional buck-boost converter, and the polarity of the output voltage is maintained positive. The battery is added at the bi-directional port, for the storage of energy through the bi-directional boost converter. The switches operate synchronously for most of the modes making the control strategy simple. The characteristics and modes of operation along with a switching strategy, are elaborated. Experimental results are presented which validate the agreement with the developed theoretical expectation.
This paper deals the grid integration of photovoltaic (PV), fuel cell, and ultra-capacitor with maximum power point tracking (MPPT). The voltage oriented control for the grid-integrated inverter is ...proposed to regulate dc link voltage. Here, the fuel cell is employed as the main renewable energy source and PV as an auxiliary source with ultra-capacitor, which compensates power variation. An integrated CUK converter is proposed for peak power extraction from PV modules. The Jaya-based MPPT method is employed to achieve fast PV tracking ability with zero deviation around maximum power point (MPP) and has accelerated searched performance in equated with particle swarm optimization (PSO) and artificial bee colony (ABC) techniques. The hybrid PV-fuel cell with ultra-capacitor as energy storage works effectively under varying operating conditions. Compared to other energy storing devices, ultra-capacitor provides a fast dynamic response by absorbing/delivering power fluctuations. The hybrid PV-fuel storage control methodologies are experimentally validated using dSPACE (DS1104) board that provides optimal power extraction with stable power affirmation for a standalone/grid-connected system.
This article proposed a nonisolated symmetrical interleaved multilevel boost converter for high-voltage microgrid applications. The proposed converter configuration is derived from the integration of ...a voltage multiplier (VM) circuit with the front-end structure of the classical two-phase interleaved converter. Moreover, equal voltage rating capacitors and diodes are suitable to design multiple stages of the proposed converter. The proposed converter can feed from two independent sources or single source in the interleaved approach. The continuous input current, high-voltage gain, reduced voltage rating of capacitor (that causes reduction in cost), reduced components, and flexibility in number of sources make the proposed converter more attractive for renewable dc-microgrid applications such as, photovoltaic (PV) system, fuel cell (FC) system, and hybrid PV-FC system. Furthermore, the voltage gain of the converter can be increased by just adding similar stages of VM without preferring the high-voltage rating capacitors and without disturbing the front-end structure of the converter. Nonidealities are considered to analyze the proposed converter in a more practical way. The characteristics and operation of the proposed converter are discussed in this article with the continuous conduction mode and Discontinuous Conduction Mode boundary conditions. The design of the reactive components and selection of semiconductor devices are discussed. Additionally, the proposed converter is compared with recently proposed dc-dc multilevel converters. To support the proposed work, simulation and experimental results are provided which shows a good agreement with the analytical approach.
In this article, a new transformer-less boost converter (TBC) is proposed to achieve high step-up voltage with a reduced voltage across switches. The proposed topology has the advantage of providing ...a high voltage gain, low voltage stress on the active switches, simplified control, and high efficiency. The structure is derived by modifying the classical switched inductor boost converter (SIBC) by replacing two of the diodes with a capacitor and a control switch, which results in a total output voltage equally shared by the two switches. Thus, the proposed converter needs a lesser number of diodes than the conventional SIBC, where the two active switches equally share the total output voltage and thereby reducing the voltage stress across the switches to half. Hence, low voltage rating switches can be used to design the proposed TBC structure. Also, a higher voltage gain is achieved using TBC without increasing the number of components of the existing SIBC. Furthermore, the proposed converter provides the common ground connection of source and load. The detailed analysis, effect of nonidealities, design, and comparison are presented. The experimental results of the proposed TBC are presented to validate its functionality and theoretical analysis.
The foremost challenge in a microgrid with Distributed Energy Resources (DER) is of managing the intermittent nature of renewable energy sources. Therefore, the extent of integration of the Battery ...Energy Storage System (BESS) has increased recently in a microgrid due to its versatility, high energy density, and efficiency. Generally, BESS is a grid-tied system and has fast power adjustment capability. Controversially, during the stand-alone mode, it cannot operate in the absence of a local Voltage Source (VS) which acts as a voltage and frequency reference in the network. To ensure the reliable operation of a microgrid during utility grid outage or non-availability of intermittent Renewable Energy Sources (RES), it is significant to operate the BESS with the local VS to dispatch the stored energy. This paper discusses the analytical methodology that can be adopted for identifying the most suitable rating of the VS which can act as a voltage and frequency reference for the BESS using Matlab/Simulink. Further, a simulation was carried out against various load characteristics and it is observed that an Uninterruptible Power Supply (UPS) with a kVA capacity of 35-45% of that of the BESS with an overload capacity of 150-200% can be chosen as a feasible choice to act as the VS.
This paper mainly focuses on the analysis, DC-transformer modeling, comparison, and experimental investigation of a non-inverting and non-isolated Nx multilevel boost converter (Nx MBC) for low to ...high DC applications. Recently, numerous isolated and non-isolated DC-DC converter configurations have been addressed for low to high DC voltage conversion purposes, which is vital for several applications (e.g., renewable energy, medical equipment, hybrid vehicles, fuel cells, DC-links, multilevel inverters, and drive applications), by utilizing and modifying the structure of reactive elements (switched capacitors and switched inductor circuitry). Among all the switched reactive structures, voltage multiplier circuitry provides a feasible solution for low to high DC voltage conversion due to its flexible and modular structure, voltage clamping capability, reduced rating of components, and ease of modification. Non-inverting and non-isolated Nx MBC combine the features and structures of conventional boost converters and voltage multiplier circuitry. DC-transformer modeling of Nx MBC is discussed for the continuous current mode (CCM) and discontinuous current mode (DCM), which helps to analyze the characteristics of the converter in a more practical way and helps to study the effect of semiconductor components, internal resistances, and load on the voltage conversion ratio of the converter. The mode of operation of Nx MBC in the CCM and DCM is also discussed with the boundary condition. The derived analysis is verified by simulations and experimental investigations, and the obtained results of 3x MBC always show good agreement with each other and the theoretical analysis.
This article presents a self-balanced multistage DC-DC step-up converter for photovoltaic applications. The proposed converter topology is designed for unidirectional power transfer and provides a ...doable solution for photovoltaic applications where voltage is required to be stepped up without magnetic components (transformer-less and inductor-less). The output voltage obtained from renewable sources will be low and must be stepped up by using a DC-DC converter for photovoltaic applications. 2 K diodes and 2 K capacitors along with two semiconductor control switch are used in the K-stage proposed converter to obtain an output voltage which is (K + 1) times the input voltage. The conspicuous features of proposed topology are: (i) magnetic component free (transformer-less and inductor-less); (ii) continuous input current; (iii) low voltage rating semiconductor devices and capacitors; (iv) modularity; (v) easy to add a higher number of levels to increase voltage gain; (vi) only two control switches with alternating operation and simple control. The proposed converter is compared with recently described existing transformer-less and inductor-less power converters in term of voltage gain, number of devices and cost. The application of the proposed circuit is discussed in detail. The proposed converter has been designed with a rated power of 60 W, input voltage is 24 V, output voltage is 100 V and switching frequency is 100 kHz. The performance of the converter is verified through experimental and simulation results.
In this article, a novel Z AC -source single-phase ac-ac converter with high buck and boost voltage conversion capability is introduced. The proposed topology utilizes the Z AC -source network to ...regulate the frequency and magnitude of the output voltage. The proposed converter operates in buck mode when the duty cycle lies between 0 and 0.33, and boost mode when the duty cycle lies between 0.33 and 1. The switching control strategy is discussed and the proposed converter provides a feature to control the magnitude and frequency of the output voltage independently. Employment of capacitors in the outer closed loop results in a highly consistent operation characterized by inherent soft commutation capability, removal of the source shoot-through risk, and enhanced input current waveform quality. Due to these advantages, it can be applied to the adjustable speed drives and traction systems. The control code is executed in dSPACE 1006 embedded with field-programmable gate array (FPGA) dS5203 board and the performance of the proposed converter is tested experimentally. The obtained experimental results are provided which validates the theoretical analysis and performance of the proposed converter.
In this paper, closed-loop control and boundary condition for continuous conduction mode and discontinuous conduction mode of nonisolated inverting N× multilevel boost converter (MBC) are ...articulated. Inverting N× MBC combines the features of classical boost converter and voltage multiplier to attain inverting N times higher voltage. Consequently, the inverting N× MBC provides a viable solution for high-voltage step-up photovoltaic applications with low voltage rating reactive components and semiconductor devices. The control strategy with saturation limiter is employed to achieve highly stable voltage. The modes of operation, benefits of inverting N× MBC, and key factors for the selection of semiconductor devices and sizing of the reactive components are discussed. Additionally, the effects of reactive components and semiconductor devices on the output voltage are examined. Experimental results of the developed circuit are presented to validate the design of converter, and effectiveness and robustness of the implemented control algorithm for different input and output side perturbations.
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