Step-up Converter Research Articles

Modeling, Development and Analysis Performance of an Intelligent Control of Photovoltaic System by Fuzzy Logic approach for Maximum Power Point Tracking

In this paper, we present an intelligent algorithm based upon Fuzzy Logic method for optimizing and improving the control performance of a photovoltaic system. The main objective of the proposed system is to pursuit the maximum power point (MPPT) under different conditions like the change of sunshine and temperature. The system consists of a photovoltaic solar module connected to a DC-DC step-up converter "Boost" and a battery - like a load . The converter parameters and the inference rule table are determined to ensure maximum output power. The effectiveness of the proposed system is validated through computer simulations using MATLAB / Simulink software and the obtained results shows that our proposed system has the best performance in term maximum power.

Efficient Multi-Phase Converter for E-Mobility

The recent growth of battery-powered applications has increased the need for high-efficiency step-up dc-dc converters. The step-up conversion is commonly used in several applications, such as electric vehicle (EV); plug-in hybrid electric vehicles (PHEV); photovoltaic (PV) systems; uninterruptible power supplies (UPS); and fuel cell systems. The input current is shared among inductors by paralleling the converters; resulting in high reliability and efficiency. In this paper; a detailed analysis for reducing power loss and improving efficiency is discussed. In continuous conduction mode; the converters are tested with a constant duty cycle of 50%. The multi phase interleaved boost converter (MPIBC) is controlled by interleaved switching techniques; which have the same switching frequency but phases are shifted. The efficiency of the six phase IBC model is 93.82% and 95.74% for an input voltage of 20 V and 200 V, respectively. The presented six phase MPIBC is validated by comparing it with the existing six phase IBC. The result shows that the presented converter is better than the existing converter. The prototype of the two phase and six phase IBC is fabricated to test the performance. It is found that the output power at the load end is highest for the 5 kHz switching frequency.

2021 best paper award winners

Both papers proposed novel designs of critical components for photovoltaic applications. Paper 1 presents a high step-up converter with an hourglass-shaped impedance network. The design allows the use of non-electrolytic capacitors, which leads to reduced size and weight, as well as longer lifetime compared to conventional converters. Meanwhile, paper 2 presents an asymmetrical multilevel inverter capable of producing up to 15 output levels. Compared to state-of-the-art solutions, it uses a minimum number of components per level. In both papers, rigorous design and performance analyses are complemented by comparative studies against existing literature solutions and corroborated by experimental validations. I wish to thank the authors of all nominated articles, wishing them success in the future, and many congratulations to the winners of this year's award. Special thanks go to Dr. Paolo Manfredi (Politecnico di Torino, Italy), member of the Editorial board, for overseeing the nominations and the selection process. My sincere congratulations to the winners.

Control of a Photovoltaic Pumping System Using the ABC Algorithm in EL Jadida Climate

In this paper, we propose a photovoltaic pumping system in the meteorological conditions of the city of EL JADIDA located in Morocco. Our system is composed of a photovoltaic generator, a step-up converter (DC/DC) controlled by Maximum power point tracking (MPPT), an inverter (DC/AC), a motor-pump group (asynchronous motor, centrifugal pump). The amount of energy produced by PV systems depends on environmental circumstances such as temperature and solar irradiance, the objective of our system is to ensure operation at a maximum power of the photovoltaic system for various climatic conditions in the city of EL JADIDA, for this the Artificial Bee method Colony (ABC) was implemented and compared to two other MPPT Perturbation and Observation (P&O) and Fuzzy Logic Control (FLC) method, to evaluate the best and most accurate controller for different weather conditions. The results show that the use of the ABC method is effective and has an excellent performance in terms of response time (3.5 H), and can increase the stability of the photovoltaic pumping system, and thanks to this algorithm, we can increase the water flow performance by 82.35% compared to the P&O method and by 50% compared to the FLC method, and we can have pumping for very low insolation d values (25.55 W/m2) for the ABC method. The simulations of the different parts of the system are developed in the Matlab/Simulink environment.

High step-up DC-DC converter based on double self-lift switched-coupled-inductor

ABSTRACT This paper presents a novel switched-inductor based DC-DC converter with high step-up capability for interfacing the low voltage input from renewable energy sources to a high voltage DC bus. In the proposed converter, coupled inductors (CIs) are employed in lieu of discrete switched inductors to enhance the voltage gain and reduce the voltage stress on the switches. The number of turns in the CI windings is properly designed and one diode-capacitor multiplier cell (DCM) is connected at each of the two secondary windings to obtain the desired high voltage gain value. Since the required voltage conversion ratio value of 15.833 is obtained by employing CIs, the switches experience only lower voltage stress levels of about 5.79% and 26.3% of output voltage under practical conditions. Experimental results obtained from 24 V-380 V, 175 W prototype converter confirm that it operates at 93.6% full-load efficiency. Further, the supply current drawn by the converter is continuous with 15.4% ripple. Simple closed-loop control is implemented to regulate the converter’s output voltage against variations in line voltage and load current.

An ultra high step‐up DC‐DC converter based on VMC, POSLLC, and boost converter

In this article, an ultra-high step-up DC-DC converter has been proposed. The topology of the converter is a combination of a cascaded boost converter, positive output super lift Luo converter (POS LLC), and a voltage multiplier cell (VMC). The lower values of the duty cycle provide a more than 10 times voltage gain. Consequently, the high voltage gain has been provided beside the lower value of the voltage/current stress of the semiconductor and an acceptable value of the efficiency. With a detailed look, it can be understood the voltage gain and efficiency of the converter have become 12 times and 90.5% based on the experimental results while the percentage of the duty cycle has become 50%. Moreover, by the mentioned percentage of the duty cycle, the normalized value of the voltage/current stress of the semiconductors has become lower than 50% by exception of only 3 semiconductor-based components which have voltage/current stresses more than 50% and lower than the unity. In addition to all the mentioned advantages, the input current has remained continuous which solves the challenges of the input filter's capacitor. Moreover, the voltage/current stresses have been kept low-valued. The ideal mode of the topology has been discussed for both continuous/discontinuous current modes. The non-ideal mode of the topology and its related comparisons have been done. A comparison of the voltage/current stresses of the semiconductor-based components has been done. Moreover, the comparison of the losses and efficiency have been done for the proposed converter and recently suggested topologies. In addition, the efficiency has been discussed for the different values of its effective factors and the resulted behavior has been expressed. Finally, the simulation and experimental outcomes have been extracted for a 120 W output power and compared with the theoretical relations' results.

Online Efficiency Optimization of a Closed-Loop Controlled SiC-Based Bidirectional Boost Converter

This article presents an online efficiency optimization strategy for a digitally controlled, wide operating range silicon carbide based boost converter with bidirectional power flow. The proposed strategy minimizes switching losses at any given operating point by adjusting the converter switching frequency and dead times to optimally set the peak synchronous rectifier turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> current. This results in the converter achieving zero-voltage switching quasi-square wave (ZVS-QSW) operation with minimum inductor current ripple. The optimal timing parameters are determined online by fit functions based on sensed input/output voltages and inductor current, and applied to the converter in a low-bandwidth feed-forward loop operating in conjunction with closed-loop regulation of the converter output voltage. The fit functions are developed from multivariate curve fitting of the analytical solutions of the minimum-conduction ZVS-QSW state plane over the complete range of operation. The proposed approach enables bidirectional operation with efficiencies greater than 97.5% for input voltages ranging from 200 to 400 V, step-up conversion ratios up to 2.5, and power levels between 2 and 8 kW. The converter also achieves efficiencies greater than 99% over wide power levels at boost conversion ratios lower than 2.

A novel dual-leg DC-DC converter for wide range DC-AC conversion

This paper proposes DC–AC Dual-leg dual-stage Conversion (DDC) and DC–AC Direct single-stage conversions (DSC). Conventional energy conversion system has only two-stage conversion, so it has some drawbacks such as huge power loss, less conversion range and lower power rating. So direct conversion, dual-leg step-up and step-up conversions are the solutions to get wide voltage conversion efficiently. The proposed converter can perform the power conversion from battery DC supply into AC with 1:1 ratio, step-up AC, and step-down AC in both directions. Also, it can perform rectifier operation from grid AC supply into DC with 1:1 ratio, step-down DC, and step-up DC. Step-up, step-down and ideal operations are possible within a single circuit; its operation is similar to solid-state DC–AC/AC–DC transformer. The ideal operation, Step-down to Step-up conversion and Step-up to Step-down conversion are possible on both sides, so this converter can handle a wide range of voltage. Power distribution is achieved with voltage regulation between battery/DC-load and AC-load/grid using the proposed control strategy with proper modulation. A prototype model of a 2-kW power rating validates the advantages and feasibility of the proposed methodology.

Presenting of the Magnetic Coupling-Based Transformer-Less High Step-Up DC-DC Converter for Renewable Energy Applications

This study presents a new high step-up converter based on the voltage multiplier cell and coupled inductor for renewable energy applications such as fuel cell and photovoltaic power systems. This converter achieves a high voltage conversion ratio using a coupled inductor and voltage multiplier cell (VMC). The voltage multiplier cell acts as a passive clamp circuit and reduces the maximum voltage across the power switch. The suggested topology has only one power switch in its structure, which leads to low cost and volume. The other benefits of the proposed structure are low components count, low input current ripple, low voltage stress throughout the semiconductors, high efficiency, zero-current switching (ZCS), and zero-voltage switching (ZVS) of diodes. Besides, due to the soft-switching condition of the diodes, the reverse recovery problem can be decreased. To show the effectiveness of the suggested topology, operation survey, steady-state analysis, and efficiency calculation are provided. Additionally, the comparison study with other similar converters illustrates the superiority of the proposed structure. Finally, an experimental prototype with 150 W rated power, 50 kHz switching frequency, and 24 V input voltage is implemented to prove the mathematical analysis and effectiveness of the proposed DC-DC converter.

Analysis of switched impedance source/quasi-impedance source DC-DC converters for photovoltaic system

This paper proposes the switched impedance source converter (SZSC) or switched quasi impedance source DC-DC converter (S-qZSC) based photovoltaic (PV) grid-connected systems. To increase the voltage from low level to high level, all PV grid-connected systems need step-up DC-DC converters. This step-up factor can be increased by connecting the terminals of a traditional quasi impedance source DC-DC converter with an additional diode and a switch. In this proposed converter, the capacitor not only serves as a filter. It is, however, bound in series to the charging loops of the inductors. On the one hand, saturated inductors can trigger instability, which can be avoided. When used for dc-ac conversion, however, the modulation index of the backend H-bridge can be set to a wider range. As compared to existing Z-source-based systems, a shorter duty period results in a higher boost factor.

A General Polynomial Reverse Design of Step-Up Converters for EV Battery Applications

The boom of electric vehicles (EVs) has urged new designs and applications of power conversion technologies. Power converters, as one of the most critical components in EV battery systems, have seen significant developments in recent years. However, thus far forward design approaches for power converter topologies have been widely adopted, which are based on engineers’ empirical knowledge and instinct. This has been deemed having low design efficiency with high randomness and limited applicability, due to the absence of a systematic guideline. This approach, though widely adopted, can no longer meet the increasingly stringent and diverse needs of today’s research and industry, with the emerging trend of renewable energy sources. Aware of these drawbacks, in this study, we propose a novel reverse design approach through establishing general polynomial relations between the topology and voltage gain of high-step-up converters, which are found to be functions of basic boost converters’ voltage gains. With this newly formed polynomial relation, a generalized approach to devising power converters for various industrial needs can be derived, which is baptized the General Polynomial Reverse Design (GPRD) approach. Three polynomial converters are derived as examples to validate the proposed method, whereby their functionality and performances are verified and tested by prototype experiments, which substantiate the proposed design theory.

Design and Implementation of a Modified Boost Topology with High Voltage Ratio and Efficiency Besides the Lower Semiconductors Stresses

This paper has designed an upgraded form of the boost topology. The voltage ratio of the traditional step-up topology has been increased in quadratic form. Moreover, a low value of the duty cycle, number of components, and voltage/current stresses besides a high efficiency are bold features. The different parameters have been extracted for the ideal/non-ideal modes of the components and continuous/discontinuous current modes. In addition, the different features, such as the current/voltage stresses, have been compared. The efficiency of the designed topology has been extracted, and its various kind of power losses have been compared. The small-signal analysis has been done, and the bode diagram of the system has been extracted. Besides the increased voltage ratio of the designed topology compared to the traditional step-up converter, the continuity of the input current has remained a brilliant feature. Moreover, the semiconductors' stresses have been low-value compared to the recently proposed topologies. Moreover, higher efficiency besides higher voltage gain has been achieved. Finally, the experimental results have been compatible with the simulation and theoretical outcomes. The higher voltage gain of the proposed converter has been caused by the lower value of the duty cycle in comparison with the conventional boost converter, besides an acceptable efficiency and semiconductor stresses.

An Integrated Boost-Sepic Higher Static Gain DC-DC Converter for Photovoltaic (PV) Based Micro-Grid Application

A new circuit topology is designed for a DC-DC converter. The proposed converter employs a single power switch which integrates a conventional boost with a single-ended primary inductor converter (SEPIC) for photovoltaic (PV) panels. A prototype is developed and implemented for 105 V DC output from 9 V DC input. The performance of the proposed topology was validated using theoretical and practical verification. The results indicated a higher voltage gain of 11.67, low duty-cycle of 0.82 and reduced voltage stress across the components of about 54 V. The circuit can be used for PV panels and other renewable energy resources that require a DC-DC voltage step-up conversion ratio.

High efficiency step-up converter using single switch with coupled inductors

Due to high demand for voltage boosting in the field of renewable energy sources, a novel topology of step-up converter with single switch is proposed in this paper. The converter uses single switch with coupled inductors architecture. The proposed topology enables to control the stepping-up gain by adjusting the duty cycle and selecting appropriate turn ratio of the coupled inductors. The two coupled inductors in the circuit can act as a step-up transformer. Moreover, the proposed technique aims to harness the turning off voltage stresses across the switching element and suppress the stress by transferring it to the load. The switching induced voltage was reduced by forwarding the power to charge a capacitor then transfer the power through a diode to the output. Circuit configuration, principles of operation and the gain transfer function of the converter are demonstrated. The proposed circuit is verified by comparing the practical results to the theoretical.

Step-Up and Step-Down Converter Integrated With Motor Inverter for Powertrain Applications

Motor inverter high-voltage regulation improves the system efficiency and reduces the dimensions of a permanent magnet synchronous motor (PMSM). This article presents an isolated inverter with step-up and step-down dc-link voltage regulation for an electrical vehicle powertrain system, which will improve the system performance in wide ranges of load and battery levels. Step-up and step-down converter and the motor inverter are merged into a single converter. Bidirectional and galvanically isolated energy transmission between battery and motor with reduced semiconductors number, easy control, and high efficiency are demonstrated. In addition, inverter transistors’ RMS current results lower than in common solutions. Topology waveforms, devices losses, and zero-voltage switching (ZVS) condition are analyzed. Based on this study, a converter design procedure to meet main electrical vehicles requirements is proposed. Converter operation and design procedure are verified by simulation and experiment in two prototypes of 3.3 kW and 300 W.

Investigation of a DC voltage boost converter based on a multifunctional integrated electromagnetic component

The methods of functional integration of discrete electrical and electromagnetic components allow to increase the reliability and efficiency of electrical energy conversion systems, to reduce their weight and dimensions. The authors proposed a solution based on replacing some individual discrete components of a DC voltage boost converter with a multifunctional integrated electromagnetic component (MIEC). The component acts as an inductor and filter capacitor. A computer model of a DC voltage boost converter based on MIEC in the MatLab software package has been developed. The graphs of the output voltage are obtained. The circuits of step-up converters of constant voltage are analyzed. The optimal for the implementation of the replacement of the inductor and the filter capacitor with a multifunctional integrated electromagnetic component has been chosen. A circuit of a DC voltage boost converter based on MIEC is assembled. Oscillograms of the output voltage were taken. The analysis of the computer model and laboratory test sample was carried out.

Resiliency-Driven Approach of DC Microgrid Voltage Regulation Based on Droop Index Control for High Step-Up DC-DC Converter

Regulation of DC microgrid voltage in presence of variable sources and loads is quite challenging. The ability of a microgrid to pay off the critical loads when subjected to disturbances, such as utility grid outage/poor climatic conditions, has gained importance recently. To address the above issues, we propose a resiliency analysis of a DC microgrid interconnected with 400 V and 200 V buses. The interconnected microgrid system is fed with solar PV along with the energy storage system and is integrated with a utility grid. Boost and high step-up DC-DC converters are employed for DC bus voltage regulation with droop index control. Here, the droop coefficient is optimized using particle swarm optimization (PSO) while maintaining uninterrupted service to critical loads and for satisfactory voltage regulation. The effectiveness of the droop index control method is tested in comparison to other optimization techniques and also with the conventional method. The resiliency analysis of the overall system, aiming for continuous power supply to the critical loads while maintaining the grid voltage unaffected, is carried out in grid outage, low solar insolation, and grid restoration conditions. The reliability of the interconnected DC microgrid test system is evaluated using the loss of power supply probability index for normal, grid outage, and grid restoration conditions. The system is implemented using PSCAD/EMTDC platform. Finally, the experimental prototype of a high step-up DC-DC converter is developed and tested to validate the effectiveness of the droop index controller with an optimized droop coefficient.

Design of an Energy Harvesting Interface Circuit Consecutively Powering Two Loads

ABSTRACT This paper presents an energy harvesting interface circuit for a single ambient energy source that consecutively delivers power supply to two loads including one light load and one heavy load. The proposed circuit consists of a step-up converter, a temporary storage element (e.g. supercapacitor), two charge control circuits for the loads, and two power transistors. The converter receives low-voltage from the output of the energy source to charge the supercapacitor at the output of the converter to high voltage levels. The supercapacitor delivers energy to the light load through corresponding control circuit. Due to the light load, the generated energy by the energy source is greater than the required power by the load. This results in accumulating the surplus energy into the supercapacitor. Once the supercapacitor stores sufficient energy, the energy direction from the supercapacitor is shifted from the light load to the heavy load. Once the supercapacitor discharges to a voltage level where the heavy load stops to receive power supply, the energy direction will be toward to the light load again. The same powering pattern will be repeated over the time. As a result, these loads operate in burst mode. The proposed circuit, constructed with off-the-shelf components, regulates outputs to nearly 3.9 V, starts the operation from an input voltage as low as 0.1 V and achieves a peak efficiency of 73.29%. The proposed circuit provides the highest output power of 124.14 mW which is greater than prior IC work supports. Apart from the highest output power, the proposed circuit meets the goal of self-sustainability since there is no need of extra power source (e.g., battery) other than the ambient energy source.

Step-Up DC-DC Switching Converter With Single Switch and Multi-Outputs Based on Luo Topology

In this paper, a step-up DC-DC multi-output converter is introduced by integrating a super-lift Luo converter, flyback topology, and coupled inductor concept. The proposed multi-output converter has positive output super-lift structure while simultaneously generating step-up voltages in its outputs. The proposed step-up converter has two non-isolated and one isolated output with a simple structure using one switch and one magnetic core. There is no voltage spike by the leakage inductance of the coupled inductor across the switch in the proposed converter. Therefore, the switch has low-stress voltage. The energy in the leakage inductor is recycled leading to higher efficiency in comparison to similar converters with the coupled inductor. The operating principles and the characteristics of the proposed converter are analyzed and discussed. The experimental results of 110W prototype verify the theoretical analysis and the benefits of the proposed converter in comparison to similar multi-output converters. The conducted electromagnetic interference evaluation of the proposed converter is presented and it is reduced using a common-mode choke.

Modular Expandable Multiinput Multioutput (MIMO) High Step-Up Transformerless DC–DC Converter

In this paper, a Multi-Input Multi-Output (MIMO) high step-up transformerless DC-DC converter is proposed. The proposed converter can expand the number of ports from both input and output terminals. Also, it has a modular structure using voltage multiplier cells (a switch, two diodes, a capacitor, and an inductor). The proposed converter is useful for a wide range of applications and has the merit of interfacing multiple hybrid voltage sources with each other to supply different loads with various voltage levels. All the output voltages of the output ports can be regulated at the same time by tuning separate controlling parameters. Since digital control has the benefit of (1) enhancing efficiency, (2) higher flexibility than analog electronics, (3) ease of use, (4) improving reliability and stability in hybrid energy conversion applications, this method of controlling implementation is adopted. The key contributions of this article would be 1) expandable modular MIMO converter with high performance for all range of duty cycles; 2) integration of hybrid energy sources and delivering to multiple loads; 3) nonlinear digital controlling approach to achieve fast transient response under the variation of input voltage sources and output loads, and 4) high voltage gain with low normalized power stress on switches. To simplify the analysis, first, single-input, dual-output (SIDO) mother-module, dual-input, three-output (DITO) and three-input, four-output (TIFO) developed modules are carefully analyzed and then, the MIMO structure is explained. To verify the theoretical results, a prototype of SIDO operation of the proposed converter with a digital controlling scheme is implemented for 30V input voltage /150V, 250V output voltages with the total power of 450W. Furthermore, experimental results of DITO operation with 30V and 40V input voltages/150V, 250V, 405V output voltages with the total power of 800W are extracted.