High Step-up Converter Research Articles

Improved high step-up converter with high efficiency for renewable energy applications

Improved high step-up converter with high efficiency for renewable energy applications

A Review on Coupled Inductor-Based High Step-Up DC-DC Converters for Renewable Energy Sources

Renewable energy sources are increasingly being embraced due to their environmental advantages, characterized by clean energy production, including solar energy, fuel cells, and wind turbines. High step-up DC-DC converters are commonly employed in conjunction with these sources to elevate their unregulated output voltage to a high and regulated level. This is especially true for converters based on coupled inductors, which are able to achieve high voltage with a low duty cycle. This paper provides a comprehensive review on the coupled inductor-based high step-up DC-DC converters. This review involves five widely used topologies, namely stacked converters, cascaded converters, multi-winding converters, interleaved converters, and integrated converters. It is evident that the researchers proposing these converters aim to enhance the overall efficiency of the renewable energy system by achieving a high voltage gain with a low duty cycle, thereby reducing conduction losses, mitigating stress on switches, alleviating voltage spikes across the main switches, and recycling the leakage energy. However, it is noteworthy that some of the proposed circuit designs are complex and involve a high number of components resulting in increase in cost and size of packaging. Additionally, some proposed circuits could not effectively achieve the aforementioned objectives. This paper serves as a valuable resource for researchers, offering an overview of the latest developments in the high step-up converters based on coupled inductor, which may help them to identify potential research gaps.

ANALYSIS OF A HYBRID CURRENT MODULATED DUAL ACTIVE BRIDGE PHOTOVOLTAIC DC/DC CONVERTER FOR UNIFORM IRRADIATION CONDITIONS

The energy of Photovoltaic (PV) modules can be connected to DC grid with high step-up ratio power electronics converters. Generally, two-stage isolated boost-based converters are used for this purpose. However, these types of converters consist of a high number of semiconductors which must withstand high voltage levels, and they utilize input inductance which has high value and large magnetic core size. To solve these problems, single-stage conversion-based Hybrid Current Modulated (HCM) isolated Dual Active Bridge (DAB) converter is proposed in the literature. However, this converter is designed for considering partial shading (PS), and PS rarely occurs in PV farms. In this study, the design methodology of DAB PV DC/DC converter is given for uniform irradiation (UI) conditions that is more suitable for PV farms. In addition, UI and PS designs of HCM DAB PV DC/DC converter are compared to each other. Analyses show that UI-based design has 3.88% smaller RMS2 current, 3.56% smaller peak current and 2.35% smaller core size than the PS-based design. Hence, UI-based design can be more efficient, cheaper, and smaller in size.

Analysis and implementation of a soft-switching high step-up quasi Z-source dc-dc converter with low voltage stress

Analysis and implementation of a soft-switching high step-up quasi Z-source dc-dc converter with low voltage stress

A Stacked Symmetrical Non-Isolated High Step-Up Voltage Gain Converter with High Efficiency and Low Voltage Stress on Components

This paper introduces a cascaded symmetrical non-isolated high step-up voltage gain converter with high efficiency and low voltage stress on components combining a non-isolated buck-boost converter and voltage doubler structure. In the proposed converter, the input source is connected in series to the output load; hence, a part of the source energy is directly delivered from source to load, not through the switching branch, improving efficiency. Furthermore, the appropriately stacked voltage doubler stage not only amplifies the high step-up voltage gain ratio but also considerably diminishes the voltage stress on all semiconductor devices and capacitors. As a result, the costless low internal resistance and low voltage components can be employed for higher efficiency, higher power density, and lower cost. To demonstrate the practicality of the proposed topology, the operating principle is outlined, and the steady-state characteristics are thoroughly analyzed. Furthermore, a 360 W prototype converter has been fabricated to confirm the efficiency of the proposed converter.

Implementation of high step-up power converter for fuel cell application with hybrid MPPT controller

As of now, there are multiple types of renewable energy sources available in nature which are hydro, wind, tidal, and solar. Among all of that the solar energy source is used in many applications because of its features are low maitainence cost, less human power for handling, a clean source, more availability in nature, and reduced carbon emissions. However, the disadvantages of solar networks are continuously depending on the weather conditions, high complexity of the solar energy storage, and lots of installation place is required. So, in this work, the Proton Exchange Membrane Fuel Stack (PEMFS) is utilized for supplying the power to the local consumers. The merits of this fuel stack are high power density, ability to work at very less temperature values, efficient heat maintenance, and water management. Also, this fuel stack gives a quick startup response. The only demerit of PEMFS is excessive current production, plus very less output voltage. To optimize the current supply of the fuel stack, a Wide Input Operation Single Switch Boost Converter (WIOSSBC) circuit is placed across the fuel stack output to improve the load voltage profile. The advantages of the WIOSSBC are less current ripples, uniform voltage supply, plus good voltage conversion ratio. Another issue of the fuel stack is nonlinear power production. To linearize the issue of fuel stack, the Grey Wolf Algorithm Dependent Fuzzy Logic Methodology (GWADFLM) is introduced in this article for maintaining the operating point of the fuel cell near to Maximum Power Point (MPP) place. The entire system is investigated by utilizing the MATLAB software.

Design and Analysis of a New High Step-Up Converter Using Switched-Inductor-Capacitor Voltage Multiplier Cells for Photovoltaic Application

Design and Analysis of a New High Step-Up Converter Using Switched-Inductor-Capacitor Voltage Multiplier Cells for Photovoltaic Application

A non-isolated high step-up converter with TID controller for solar photovoltaic integrated with EV

A non-isolated high step-up converter with TID controller for solar photovoltaic integrated with EV

Analysis and Design of Switched LC Converter With Reduced Voltage Stress for Photovoltaic Applications

High step-up voltage conversion is required in renewable energy systems. This paper presents a non-isolated high step-up DC-DC converter based on active switched-inductors (ASL) with switched capacitor cells (SCC). The unique selling proposition of the proposed converter is division of input current which reduces the inductor size. In the proposed topology, the capacitor and diode are arranged in such a way that they interconnect the input to the load side for obtaining high step-up ratio. The main advantages of the converter are high step-up ratio at a low duty cycle with low switch stress and low component count. Operating principles, design equations, and device stress are included in this paper. Moreover, small-signal analysis and its bode plots are presented here. In addition, the loss distribution is critically investigated. Finally, to verify the theoretical study, a laboratory prototype is built and tested at different operating points in continuous conduction mode (CCM).

Extendable Multiport High Step-Up DC–DC Converter for Photovoltaic-Battery Systems With Reduced Voltage Stress on Switches/Diodes

In the standalone photovoltaic (PV)-battery power system, a multiport converter is more desirable than several single-input converters as it has advantages of the simpler circuit, higher efficiency, and lower cost. In this paper, a novel structure based on a non-isolated high step-up multi-port converter (MPC) is proposed. The proposed MPC has the capability of providing high voltage gain and low normalized peak inverse voltage (NPIV) across semiconductor devices. Maximum power point tracking (MPPT) algorithm can be applied for each PV input source, which is an effective method to prevent mismatches among PV modules. Different from the existing extendable MPCs, the proposed MPC can extend both unidirectional input ports and bidirectional ports to involve more types of renewable energy sources and energy storage devices. Continuous input currents and modularity are the other profits of the proposed MPC. Various operating modes, steady-state analysis, and design considerations have been discussed. Comparison results verify the above advantage of the proposed MPC. Finally, a 240W laboratory prototype is designed to validate the performance of the proposed MPC.

A Novel Three-Winding Coupled Inductor-Based High Step-Up DC-DC Converter for Renewable Energy Application

This paper presents a novel nonisolated high step-up dc-dc converter for renewable energy generation system. The converter combines a three-winding coupled inductor, voltage multiplier cells, and two power switches with simultaneous operation. Compared with existing high step-up converters, the proposed converter can achieve high voltage gain under a low number of turns ratio while avoiding a large duty cycle. Moreover, the passive clamp circuit recycles leakage inductor energy and reduces the voltage spike of switches. Continuity of input current and existence of a common ground between the input energy source and load make the converter suitable for renewable energy applications. Also, the proposed converter shares high voltage gain with low voltage stress on semiconductors (switches/diodes), improved compactness and high efficiency. The operating principles and steady-state analysis of the proposed converter are illustrated. Then the theoretical efficiency analysis, and performance comparison with other converters are discussed. Finally, a 200 W prototype with 380 V output voltage is established based on the design guidelines, and experimental results verify the accuracy of the theoretical analysis.

High Step-Up Current-Fed Diode-Clamped Resonant Converter for Overloaded Fuel-Cell Vehicles

We propose a high step-up current-fed diode-clamped resonant converter for overloaded fuel-cell vehicles. The electric motor is able to demand short-time peak torque during sudden acceleration phase or long-time excessive torque when the fuel-cell vehicles are overloaded. Then, the conventional converter suffers from a high current spike at the secondary-side switches. The proposed converter incorporates diode-clamped cell on the secondary side, and therefore does not have the high current spike, but retains the benefits of the conventional converter such as high step-up function, ripple-free characteristic, and soft switching capability. When the output power is over its maximum nominal value, the secondary-side switches are switched off with complete zero-voltage-switching (ZVS) and the secondary-side diodes are off with zero-current-switching (ZCS). As a result, the proposed converter exhibits high efficiency and long-term operation under the nominal power and even at peak power. Furthermore, we have analyzed voltage gain, ZVS/ZCS region, and current/voltage stress on the active power components when the output power is over its maximum nominal value, which is different from those when the output power is in its nominal range. The theoretical analysis of the proposed converter is presented, then validated using a laboratory-built prototype.

Micro High Step-Up Converters for Energy Conversion of Ion Engines

Micro High Step-Up Converters for Energy Conversion of Ion Engines

Tri-State Coupled Inductor Based High Step-Up Gain Converter Without Right Hand Plane Zero

This brief proposes a novel tri-state Coupled Inductor (CI) based high step-up gain converter without Right Half Plane (RHP) zero. The basic Coupled Inductor based Boost Converter (CIBC) can achieve high step-up gain by changing the turn ratio of CI and duty cycle. However, the control to output voltage transfer function of basic CIBC converter in CCM has RHP zero hence non-minimum phase behavior with limited bandwidth and unstable operation of the converter when step changes in duty cycle. RHP zero can be eliminated from the basic CIBC by providing freewheeling period in converter operation hence additional degree of freedom to control energy transfer to output capacitor. Thus, the converter achieves stable operation and improves the bandwidth. The small-signal model of the proposed converter is derived to verify the claim. All theoretical findings are verified by experimental results. Experimental results are provided from implemented laboratory prototype of input voltage of 24 V to output voltage of 100 V and 200 W power.

Analysis and Design of a New High Voltage Gain Interleaved DC–DC Converter with Three-Winding Coupled Inductors for Renewable Energy Systems

In this article, a new non-isolated interleaved DC–DC converter is proposed to provide a high voltage conversion ratio in renewable energy systems. The converter configuration is composed of a two-phase interleaved boost converter integrating a voltage-lift capacitor and three-winding coupled inductor-based voltage multiplier modules to achieve high step-up voltage conversion and reduce voltage stresses on the semiconductors (switches and diodes). The converter can achieve a high voltage conversion ratio when working at a proper duty ratio. The voltage stresses on the switches are significantly lower than the output voltage, which enables engineers to adopt low-voltage-rating MOSFETs with low on-state resistance. The switches can turn on under zero-current switching (ZCS) conditions because of the leakage inductor series reducing switching losses. Some diodes can naturally turn off under ZCS conditions to alleviate the reverse–recovery issue and to reduce reverse–recovery losses. The input current has small ripples due to the interleaved operation. The leakage inductor energy is recycled and voltage spikes on the switches are avoided. The proposed converter is suitable for applications in which high voltage gain, high efficiency and high power are required. The principle of operation, steady-state analysis and design considerations of the proposed converter are described in detail. In addition, a closed-loop controller is designed to reduce the effect of input voltage fluctuation and load change on the output voltage. Finally, a 1000 W laboratory prototype is built and tested. The theoretical analysis and the performance of the proposed converter were validated by the experimental results.

Applying a Multiple-Input Single-Output Interleaved High Step-Up Converter with a Current-Sharing Device Having Different Input Currents to Harvest Energy from Multiple Heat Sources

In this paper, a thermoelectric conversion system for multiple heat sources is proposed. For design convenience, the overall system employs only a single-stage converter. Such a converter uses coupling inductors and switched capacitors to increase the voltage gain. In order to reduce the high-frequency voltage oscillation of the turn-off of the main switches created from leakage inductors, two active clamp circuits with zero voltage switching (ZVS) turn-on are employed. By doing so, although the current-sharing device with interleave control is embedded in the proposed converter, the input currents can be unequal. Therefore, the inputs of the converter can operate under individual maximum power points and transfer the energy from different thermoelectric generators (TGs) to a single load. Furthermore, the main switches have low voltage stress during the turn-off period. As for the maximum power point tracking (MPPT) method, it utilizes a three-point-weighting method to improve the tracking stability. In addition, the number of inputs of this converter can be extended. The MPPT simulation is presented to verify the feasibility as well as several experimental waveforms to demonstrate the effectiveness. The field programmable gate array (FPGA) is used as a digital control kernel to control the thermoelectric conversion system.

High Step-Up Gain Converter Based on Two-Phase Interleaved Coupled Inductor Without Right-Hand Plane Zero

This paper proposed a novel two-phase interleaved Coupled Inductor (CI) based high step-up gain converter without Right Half Plane (RHP) zeros for a wide operating range of duty cycle. A coupled inductor between input and output is used in the proposed converter to eliminate RHP zero. The energy of CI is transferred to output capacitor when switch is ON to eliminate RHP zero. Furthermore, the converter has a wide operating range to eliminate RHP zero with a coefficient coupling of CI near one. Thus, the converter achieves higher bandwidth and a wide range of control over output voltage. The small-signal model of proposed converter is derived to verify the proposed claim. The single loop voltage control is sufficient to regulate output voltage of the converter with a good stability margin and faster dynamic response for a wide range of load changes. In addition, proposed converter has a high voltage step-up gain and low voltage stress on switching devices compared to the boost converter. Moreover, interleaved operation at input side reduces ripple and increases power density. All theoretical findings are verified by simulation and experimental results. Experimental results are provided from implemented laboratory prototype of input voltage of 24 V to output voltage of 100 V and 200 W power.

High-Frequency Characteristics Analysis of Transformer-Based Voltage Multiplier in Lightweight Process of Unidirectional High Step-up Converters for Offshore Wind Farms

To realize the lightweight of unidirectional high step-up converters for offshore wind farms, it is necessary to increase the switching frequency. However, there is a gap in the analysis of the switching frequency effect, the frequency characteristics of the converter are not clear enough to provide theoretical guidance for the high-frequency design. To address this problem, the effect of switching frequency on the voltage conversion ratio (VCR) and maximum output power (MOP) of the widely used transformer-based voltage multiplier (TBVM) in unidirectional high step-up converters is discussed in this paper. More accurate mathematical models for two types of TBVMs, pulse-width-modulation TBVM (PTBVM) and resonant TBVM (RTBVM) are established. The effect of frequency on VCR, MOP, stresses together with losses is analyzed in detail accordingly. Theoretical analysis and comparison show that, in PTBVM, the increase in switching frequency decreases MOP and enlarges the VCR sensitivity to the load, and power switches suffer from large current stresses due to circulating power. In contrast, RTBVM is more suitable for high-frequency applications for the following advantages: duty cycle independent characteristics, higher maximum output power, higher efficiency, and load-insensitive VCR. Finally, experiments at 100 kHz switching frequency verified the theoretical analysis.

An Interleaved High Step-Up DC/DC Converter-Based Three-Winding Coupled Inductors With Symmetrical Structure

This paper proposes an interleaved high step-up converter based on three-winding coupled inductor (TW-CI) with symmetrical structure. By utilizing the TW-CI along with a voltage multiplier cell, the proposed converter achieves high power transfer ability as well as minimized voltage stress across power switches and diodes. The converter has significantly improved the voltage gain by integrating two TW-CIs with the passive clamp circuit. The leakage inductor energy of the TW-CI is recycled to improve the voltage gain and efficiency while facilitating the soft switching condition for the power switches. Additionally, the voltage stress across the power switches is decreased with the help of the clamping capacitors. Therefore, low-voltage-rated semiconductors with small on-resistance can be chosen which reduce conduction losses and improve the overall performance. Moreover, two series-connected capacitors of the primary side are introduced, which effectively balance the voltage between the power switches and the capacitors during steady and dynamic states. Finally, a 400W experimental prototype with 24V-400V is built to is verify the accuracy of proposed converter.

Rigdelet Neural Networks-based Maximum Power Point Tracking for a PEMFC connected to the network with Interleaved Boost Converter optimized by Improved Satin Bowerbird Optimization

This paper proposes a new control policy for optimal control of the 3-phase system of PEMFC connected to the grid. This also includes a 3-phase high step-up Interleaved Boost Converter (IBC) to amplify the PEMFC outputted voltage. To control the PEMFC system, Maximum Power Point Tracking (MPPT) based on Rigdelet Neural Networks (RNN) has been utilized, and to improve this controller, an improved version of the Satin Bowerbird Optimization (ISBO) algorithm has been utilized. The main advantage of the proposed improved version is modifying the convergence weakness and fixing convergence in chaos theory. The method is then validated by performing it one time on a standalone PEMFC system and another time on a grid-connected PEMFC system. Simulation results indicate that based o the IBC converter, better results with lower current ripples can be achieved. Also, the method has the ability to feed to both active and reactive powers by keeping stable the sudden temperatures. Final results have been also put in comparison with two different latest techniques to indicate the technique proficiency.