High Voltage Conversion Ratio Research Articles

A high step‐up high step‐down coupled inductor based bidirectional DC–DC converter with low voltage stress on switches

AbstractThis paper proposes, a novel soft‐switching bidirectional direct current to direct current (DC–DC) converter based on switched‐capacitor and coupled‐inductor. The proposed converter has a simple structure and utilizes four switches and a three‐winding coupled inductor and can achieve a high voltage conversion ratio in both step‐up/step‐down operations. By employing the switched‐capacitor technique, voltage stress across the power switches is low and therefore low voltage rating switches can be adopted to reduce the losses of their conduction. Soft‐switching characteristic of the proposed converter reduces the switching loss of active power switches and raises the conversion efficiency. This paper presents theoretical analysis for all operating modes of the converter, voltage conversion ratio, voltage and current stresses of all power switches. Finally, to test the validity of theoretical results and demonstrate the performance of the converter, experimental results are provided.

Enhanced Control of Polymer Electrolyte Membrane Fuel Cell Fed Basic Series Positive Super Voltage Lift Luo Converter Using Interval Type-2 Fuzzy Logic

An eco-friendly and renewable energy source, Polymer Electrolyte Membrane (PEM) fuel cells offer various advantages such as stability and efficiency. The present study designs a basic series positive super voltage lift Luo (PSVLL) converter which, to produce a PEM fuel cell with a low output voltage, yields a low input current ripple and a high voltage conversion ratio. Additionally, it proposes an interval type-2 fuzzy logic (IT2FL) controller to maintain the output voltage of the proposed converter at a specified value. The model, which consists of a fuel cell and a basic series PSVLL converter, was designed in Matlab/Simulink simulation environment. The enhanced control of the proposed converter output voltage was performed using an IT2FL controller. The simulation results demonstrated that using the proposed controller, the PEM fuel cell fed basic series PSVLL converter reached the specified boundary current and voltage variation ratios under nominal operating conditions and at different reference voltage ranges within a short duration.

A Novel Hybrid MPPT Controller for PEMFC Fed High Step-Up Single Switch DC-DC Converter

At present, there are different types of Renewable Energy Resources (RESs) available in nature which are wind, tidal, fuel cell, and solar. The wind, tidal, and solar power systems give discontinuous power supply which is not suitable for the present automotive systems. Here, the Proton Exchange Membrane Fuel Stack (PEMFS) is used for supplying the power to the electrical vehicle systems. The features of fuel stack networks are very quick static response, plus low atmospheric pollution. Also, this type of power supply system consists of high flexibility and more reliability. However, the fuel stack drawback is a nonlinear power supply nature. As a result, the functioning point of the fuel stack varies from one position to another position on the V-I curve of the fuel stack. Here, the first objective of the work is the development of the Grey Wolf Optimization Technique (GWOT) involving a Fuzzy Logic Controller (FLC) for finding the Maximum Power Point (MPP) of the fuel stack. This hybrid GWOT-FLC controller stabilizes the source power under various operating temperature conditions of the fuel stack. However, the fuel stack supplies very little output voltage which is improved by introducing the Single Switch Universal Supply Voltage Boost Converter (SSUSVBC) in the second objective. The features of this proposed DC-DC converter are fewer voltage distortions of the fuel stack output voltage, high voltage conversion ratio, and low-level voltage stress on switches. The fuel stack integrated SSUSVBC is analyzed by selecting the MATLAB/Simulink window. Also, the proposed DC-DC converter is tested by utilizing the programmable DC source.

Non-Isolated High Gain Interleaved DC–DC Converter with Voltage Multiplier and Switched Capacitor for Renewable Energy Systems

A novel non-isolated high-gain DC–DC converter for green energy employment is presented and analyzed. The proposed converter comprises a switched capacitor cell, passive clamp circuit, coupled inductors, and voltage multiplier unit. An interleaved boost converter (IBC) is placed on the input side of the proposed design. The voltage multiplier unit (VMU) with the secondary windings of the coupled inductors is located on the load side. It is used to accomplish interleaved power storage. The leakage energy of coupled inductor is recirculated to the load side, and the reverse recovery problem of diodes is effectively suppressed. As a result, a low-on-state resistance power switch with a low voltage rating is employed and minimizing conduction losses. The presented topology is suitable for sustainable energy applications due to its low operating duty cycle, high voltage conversion ratio, and higher efficiency. The output voltage causes substantially low voltage stress on semiconductor switches and passive elements. This proposed paper deals with simulation, parameter selection, experimental design, results and discussion. The simulation is verified using MATLAB/Simulink with a DC voltage of 30–517[Formula: see text]V. To validate the design analysis, a 1.5-kW experimental prototype is designed with a switching frequency of 10[Formula: see text]kHz and attained an efficiency of 96.07%.

A single switch high gain multilevel boost converter with switched inductor topology for photovoltaic applications

This paper proposes a new transformer-less single-switch high-gain dc-dc converter for solar power systems. The suggested converter is created by supplementing the conventional boost converter with a switched inductor cell plus a voltage multiplier stage. The converter has several benefits, including a high voltage conversion ratio, reduced voltage stress on semiconducting switches and diodes, a reduction in the need for gate drivers because only one switch is used, as well as constant input current to prolong the lifespan of the photovoltaic cell. The analytical waveforms of the recommended converter can be seen in the continuous conduction mode (CCM). The analysis of voltage stress is done. In the presence of parasitic components, increased voltage gain and efficiency were also obtained.The proposed high-gain converter topology is compared to recently published high-gain converter topologies in terms of performance. Using PSIM, a high-gain dc-dc converter's performance is studied and analysed with regard to its low switching voltage stress. The suggested converter is successful in stepping up 20V to 400V at 160W power capacity, while offering a continuous input source current at 95% efficiency.

Double‐input triple‐output non‐isolated DC–DC converter based on coupled inductor with high step‐up output voltages

SummaryThis paper introduces a new non‐isolated double‐input triple‐output (DITO) high voltage gain DC–DC converter with a wide range of applications, including hybrid voltage source systems, solar home appliances, DC‐bus power distribution systems, and electrical vehicles (EVs). The proposed DITO converter interfaces two hybrid voltage sources to supply three different output loads with varying voltage and power levels. Compared to conventional converters of the same type, the proposed DITO converter offers several advantages, including operation for all duty cycles, integration of hybrid energy sources to transfer power to multiple loads, high voltage conversion ratio for all three‐output ports, a higher ratio of total voltage gain to total components number, common grounded input and output DC ports, simultaneous DC voltage regulation of three‐output ports by tuning separate controlling parameters of duty cycles, an additional turns ratio of coupled inductors to increase the voltage gain of output ports, and medium voltage stress on switches. The proposed DITO converter utilizes a new single‐switch single‐coupled‐inductor DC–DC structure, which is analyzed and verified through a prototype implementation for 25 and 30 V input voltages and 210, 330, and 400 V output voltages with a total power of 480 W. The experimental results confirm the simulation results and theoretical analysis.

A novel bidirectional DC–DC converter with high voltage conversion ratio and capability of cancelling input current ripple

AbstractThis paper proposes a novel bidirectional DC–DC converter with high voltage conversion ratio and capability of cancelling input current ripple. The proposed converter uses two coupled inductors and switched‐capacitor circuit to increase the voltage conversion ratio. The input current ripple at low voltage side can be eliminated for a pre‐selected duty cycle by adjusting special values of magnetizing inductances of coupled inductors. The input current is divided into two paths of the primary winding of coupled inductors that causes the decrease in the current stresses of switches. The proposed converter has five switches that consist the internal diodes of switches to bring about bidirectional power flow and have boost and buck operations. Here, the proposed topology is analysed in all operating modes and the current and voltage stresses of switches, input current ripple cancelling condition and voltage conversion ratio are calculated. Finally, the accuracy performance of the proposed converter is reconfirmed through EMTDC/PSCAD simulation and experimental results for boost operations.

Analysis and small‐signal modelling technique for support bus DC‐link of front‐end coupling inductance high step‐up single switch boost converter in low voltage renewable source

AbstractThis study proposes a non‐isolated DC converter, which is connected in series with an inverter, with a high output voltage conversion ratio for application in electricity generation systems to upgrade low‐voltage to high‐voltage DC. The topology of the proposed converter is based on a boost converter, which has the limitation of a low voltage conversion ratio. The converter is developed and connected using a coupling inductance technique by adding a second winding L2 coupled with the prototype winding and diode D2. This technique increases the voltage ratio via the ratio operator (N) of both the induction coils by operating a single switch at a constant frequency of 60 kHz. The working principle of the proposed converter is based on pulse width modulation with a duty cycle ≤40%. When the converter receives a low voltage DC input of 36 V, it converts the input to a high output voltage of 325 V at an output power 125 W, showing a circuit efficiency of 92.48% at full load. The synthesis and design of the controller include a linear approach to represent the parameters using the small signal methodology, which is employed to establish a transfer function. Furthermore, the proposed converter is capable of effectively regulating the output voltage, even when subjected to variations in the output load by employing a proportional–integral control mechanism. The close loop results obtained from simulations and practical implementation verified the proposed circuit design, as both results agreed with the theoretical analysis.

A novel on high voltage conversion ratio DC‐DC converter for EV‐fed fuel cell application with hybrid MPPT controller

SummaryAs of now, nonrenewable energy sources are not used for automotive industrial applications because their disadvantages are high installation costs, more maintenance costs, and less adaptability all over the places in the world. Also, these sources produce highly flammable gasses in the environment. So, in this work, a Proton Exchange Membrane Fuel Stack (PEMFS) is used as an input source for the proposed system. The PEMFS generated voltage value is very low which is improved by integrating the proposed Single Switch High Voltage Conversion Ratio (SSHVCR) DC‐DC converter. The properties of this SSHVCR converter are less component utilization for reducing the ripple ratio, more flexibility, less voltage stress, and high voltage conversion ratio. In the second objective, a Differential Step‐Grey Wolf Optimization (DSGWO) with Adaptive Fuzzy Logic (AFL) controller is used for generating switching pulses to the DC‐DC converter. The merits of DSGWO‐AFL controller are quick dynamic response, moderate design complexity, good adaptability, and needed few number iterations for identifying the MPP of PEMFS. The overall proposed system is studied by applying the MATLAB/Simulink tool at rapid changes in the operating temperature of the fuel cell stack.

Design and implementation of hybrid MPPT controller for FC based EV system with boost DC-DC converter

The fuel cell-dependent electric vehicle systems are giving an important role in the present automotive systems because their features are less air pollution, high flexibility, reduced oil dependency, and more reliability. However, the fuel stack delivers nonlinear output V-I characteristics. So, the extraction of peak power from the fuel source is very difficult. In this work, a Variable Step Size Radial Basis Functional Network-based Adaptive Fuzzy Logic Controller (VSSDE-AFLC) is proposed for tracking the peak power point of the fuel cell system. The merits of the proposed Maximum Power Point Tracking (MPPT) controller are high tracing speed of functioning point of the fuel cell, more flexibility, high abundant, acceptable oscillations across MPP, and less dependency on modeling of the fuel stack. Also, the single switch converter is utilized for increasing the voltage supply of the fuel cell. The features of the proposed converter are wide input operation, less voltage stress, high supply voltage conversion ratio, and good dynamic response. The proposed fuel cell-dependent boost converter is implemented by utilizing the MATLAB/Simulink software, and the converter is tested successfully by using the desired programmable DC supply.

Ripple-Free Bidirectional DC–DC Converter With Wide ZVS Range for Battery Charging/Discharging System

A ripple-free bidirectional dc-dc converter (BDC) with wide soft-switching range is proposed for battery charging/discharging application in this paper. On battery side, the current ripple can maintain zero by two-phase interleaving technology in spite of the battery voltage and transfer power variation. Through series connection, high voltage conversion ratio and reduced voltage stresses of switches can be achieved effectively. The built-in transformer technology allows for a small magnetic component size, due to its inherent saturation avoidance. With the proposed control law, the control variables can be decoupled. The duty cycle is fixed by battery side voltage while the transfer power can be regulated monotonously by phase-shift angle. Theoretical derivation illustrates that soft switching can be obtained in all switches by adopting proper parameter design. Furthermore, comparative analysis shows the proposed converter is suitable for battery charging/discharging applications. The experimental verification proves the merits of the proposed converter by a 40-60V/400V 1 kW prototype.

Bridgeless Modified High-Step-Up Gain SEPIC PFC Converter Based Charger for Light EVs Battery

This study presents a two-stage on-board charger for light electric vehicles (LEVs) with low voltage battery (24-72V). The front-end of the charger has characteristics of high voltage conversion ratio and unity power factor operation achieved by a bridgeless high gain modified SEPIC converter. The high voltage conversion ratio enables the front-end to operate over a wide range of input voltages. At the back-end of the charger, an isolated positive output Luo DC-DC converter is employed to regulate the charging profile of the LEV battery under constant current (CC) and constant voltage (CV) charging modes. The presented charger operates in discontinuous conduction mode (DCM), which has dual advantages of having inherent feature of power factor correction (PFC) at the supply end along with significantly reducing the complexity of control mechanism, thereby reducing the cost and effort of control implementation. The operational analysis and design of the presented charger in DCM are covered in detail in this study and the same are further validated by means of simulations. A 650 W test bench setup is developed to authenticate the theoretical performance by means of experimental results. The experimental performance of the front-end is finally compared with other PFC topologies to highlight the merits and demerits of the presented charger.

Design and Control of Two Stage Battery Charger for Low Voltage Electric Vehicles Using High Gain Buck-Boost PFC AC-DC Converter

The design and control of a two-stage onboard battery charger (OBC) for the low-voltage electric vehicle (LVEVs) are presented in this study. The presented charger operates over a wide range of AC input voltage at high power factor. The presented charger utilizes a bridgeless high gain high power factor AC-DC converter with continuous input current characteristics at its front end. At the back end of the charger, an isolated Cuk DC-DC converter is employed to control and implement different battery charging modes, viz. constant current (CC) and constant voltage (CV) charging profiles. The presented AC-DC converter operates under discontinuous current mode (DCM) operation and achieves minimum control complexity at the AC-DC stage. The DCM design and high voltage conversion ratio allow it to function reliably over a comprehensive range of input and intermediate DC link voltage. This study covers the charger's design for a power rating of 650 W and output battery voltage of 24 to 72 V. The overall operational analysis and effectiveness of the design are verified through both simulations and experimental implementation and the performance is compared with other contemporary power factor correction (PFC) topologies on various parameters.

A Novel Non-Isolated Dual-Input Single-Output High Step-Up DC/DC Converter With Coupled Inductors

This paper proposes a novel non-isolated dual-input single-output high step-up DC/DC converter with coupled inductor (NI-DISO-CI) for the distributed sources. The coupled inductor along with the passive clamp circuits is employed to the NI-DISO-CI, which can achieve the high voltage conversion ratio without operating at an extremely duty cycle. The energy stored in leakage inductor is recycled by the passive clamp circuits, which can minimize the voltage spikes across power switches. Therefore, the power switches with low parasitic parameters can be selected. And the power switches can achieve the zero current switching (ZCS) performance by utilizing the leakage inductor from coupled inductor. The operating principle, steady-state analysis, design and performance of the NI-DISO-CI are described in detail. Finally, the experimental prototype with the switching frequency of 100 kHz and the power rating of 400W is built to verify the accuracy of the theoretical analysis.

An improved coupled inductor‐based quadratic step‐up DC–DC converter with a high step‐up factor and reduced voltage overshoot on the power switch

AbstractMost coupled inductor‐based step‐up DC–DC converters encounter a significant voltage overshoot on their power switch due to the leakage inductance of the coupled inductor. So, they need additional bulky snubber circuits or a sophisticated procedure for coupled inductor design to reduce that effect. This paper proposes an improved coupled inductor‐based DC–DC converter, which provides a high quadratic voltage conversion ratio without excessive voltage stresses on the power switch. An active clamp circuit that operates with the zero‐voltage switching (ZVS) feature has been utilized for this aim. This feature allows the main power switch to be selected from low voltage ratings and low on‐resistance MOSFETs, which reduces conduction loss. The topology also benefits from continuous input current, high gain, high efficiency, and an appropriate number of components compared with the produced gain. In this article, the theory and operation of this converter are described by proposing the dc and small‐signal models, loss model, and continuous and discontinuous current modes (CCM and DCM) relations. Experimental results are represented to evaluate the performance of the proposed topology. For this purpose, a 240 V/240 W prototype has been designed and fabricated. Results confirm the above claims.

A non‐isolated DC‐DC topology with high voltage rate based on magnetic coupling and voltage multiplier method

SummaryIn this study, a novel non‐isolated DC‐DC converter based on magnetic coupling and voltage multiplier technique has been proposed. The output voltage of the suggested converter can be enhanced by selecting the appropriate turn ratio of the coupled inductor. To further improve the voltage gain, a voltage multiplier circuit including the capacitors and diodes has been utilized in this converter. The main features of the proposed converter are a high voltage conversion ratio, high efficiency, and lower peak voltage throughout the semiconductor devices. Besides, there are soft switching conditions throughout the diodes of the presented topology, which leads to reducing the reverse recovery losses of the diodes and subsequently improving the overall efficiency of the system. Also, only one insulated‐gate field‐effect transistor (MOSFET) has been used in the structure of the converter. Thus, the switch with lower on‐state resistance can be selected for the suggested converter that decreases the conduction losses. To prove the performance of the suggested structure, the operational analysis, mathematical descriptions, efficiency analysis, and comparison survey with similar structures in the literature have been described. Finally, a laboratory prototype with 200 W output power with 95.14% load efficiency, 20 V input voltage, and 260 V output voltage at 50 kHz switching frequency has been provided.

Design and Analysis of a Non-Isolated DC-DC Converter With a High-Voltage Conversion Ratio

In this letter, a new non-isolated high gain DC-DC converter topology is proposed to attain the high-voltage conversion ratio. The high-voltage conversion ratio is achieved without utilizing the coupled inductors and any transformers. The proposed topology utilizes a single power semiconductor switch and its operation is examined under continuous conduction mode (CCM), discontinuous conduction mode (DCM) and boundary conduction mode (BCM). The theoretical analysis and design procedure for passive components are provided with mathematical expressions. The validity of the theoretical analysis is examined by using a laboratory prototype of the proposed converter with a power rating of 200 W. The experimental results are taken under CCM with a 60% duty cycle. The proposed topology is also examined with dynamic changes in duty cycle value and load values. The efficiency and power density of the proposed converter are 90% and 1.03kW/L.

H5-CFDAB: A Current-Fed Dual-Active-Bridge Converter for Application in Modular DC Solid-State Transformer

Isolated DC-DC converters in DC Solid-State Transformers (DCSSTs) must conform to stringent requirements such as high voltage conversion ratio, high efficiency, and reliable operation with grid fault handling capabilities. This paper proposes a novel current-fed Dual-Active-Bridge (CFDAB) converter, named H5-CFDAB, for modular DCSST application. Compared to the existing topologies, the proposed converter provides a single-stage power conversion with reduced component count and semiconductor Volt-Ampere (VA) rating. The proposed modulation scheme makes the pulse widths of the transformer winding voltages independent of the duty ratio. This allows further optimization of the high-frequency-link (HFL) characteristics like minimized HFL conduction losses and full range Zero-Voltage-Switching (ZVS) at turn ON for the switches, further increasing the converter efficiency. Several modules of the proposed H5-CFDAB converter connected in Input-Series-Output-Parallel (ISOP) configuration makes the system suitable for Medium-Voltage (MV) high-power applications. The operation of the proposed converter is analyzed in detail, including the HFL characteristics and derivation of the ZVS conditions for the switches. In addition, a closed-loop control scheme is proposed for achieving tight regulation of the converter outputs during transients. A 1.2 kW laboratory prototype is built to verify the effectiveness of the proposed converter, along with the control scheme.

A Novel High-Voltage-Gain Quasi-Resonant DC–DC Converter With Active-Clamp and Switched-Capacitor Techniques

We propose an isolated high-voltage-gain quasi-resonant dc-dc converter with a bi-functional circuit for the renewable energy applications. The proposed converter adopts an interleaved connection in the primary side, reducing input current ripple, and includes the bi-functional circuit operating as the switched-capacitor cells and two active-clamped circuits simultaneously. The converter realizes high voltage conversion ratio without using extreme duty ratio, and the voltage spike due to the leakage inductance of the isolation transformer is clamped. In addition, an output voltage doubler in the secondary side comprises a series resonant circuit and then obtains zero current switching (ZCS) turn-off of rectifying diodes; the diode reverse recovery problems are also alleviated. A 320W laboratory prototype that operates at input of 26 V-34 V and output of 400 V is fabricated to verify the effectiveness of the proposed converter.

SVPWM control strategy for Novel Interleaved High Gain DC converter fed 3-level NPC Inverter for Renewable Energy Applications

The high-gain DC converter is a crucial step in the conversion process for raising the voltage from PV panels to the desired voltage level in renewable energy applications. This article proposes a three-phase grid connected PV system with a novel interleaved high gain DC converter fed 3-level Neutral-Point-Clamped (NPC) Inverter. The novel high-gain DC converter consists of an interleaved boost converter (IBC) at its input side, a switched capacitor cell, a passive clamp circuit, and a voltage multiplier unit (VMU). The interleaved arrangement eliminates the input current ripple, and the VMU is utilized to improve the overall voltage gain besides the reverse recovery problem of diodes. The proposed converter is operated at a duty cycle D = 0.6 and a high voltage conversion ratio of 17.5 which is ideal for sustainable energy applications. This paper uses the proposed converter for a grid-connected solar PV system with an NPC inverter controlled using Space Vector Pulse Width Modulation (SVPWM) technique. The SVPWM strategic approach is a prevalent modulation technique for NPC inverter due to its extensibility in choosing the ideal voltage vectors. It uses an active filter, which is more dependable, dynamically better behaved, and capable of operating accurately under distorted grid voltages under varying load conditions. The proposed grid-associated PV system with a novel interleaved converter and 3-level NPC inverter is employed in Matlab/SimPower System and experimentally verified. Power loss and efficiency calculations were performed on the DC converter side, and the efficiency was 96.07%. NPC inverters have a THD of 22.2%. Results from simulations and experiments indicate that the suggested topology can efficiently extricate the maximal amount of power from PV modules and inject energy into the grid system with excellent steady-state and dynamic performance.