High Voltage Conversion Research Articles

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%.

Reactive power capacity allocation technology of shore‐based power supply system of offshore oil production platform under different network topology reliability measures

AbstractTo improve the economy of offshore oil production platform shore‐based power transmission mode, the reactive power capacity allocation technology of offshore oil production platform shore‐based power supply system based on different network topology reliability measures was proposed. The optimization model of power supply system network topology and the structure model of voltage source converter high voltage direct current transmission system were established, the start and stop control scheme of flexible direct current (DC) transmission system was designed, and the operation parameters of converter station and DC line were monitored in real time. The topological structure of offshore oil production platform shore‐based power supply system is constructed, the mathematical model of flexible DC transmission system is established when the alternating current side voltage is balanced, the reactive power capacity configuration of offshore oil production platform shore‐based power supply system is optimized, and the life cycle cost results are calculated. The experimental results show that the algorithm proposed in this paper can obtain the optimal solution only after 26 calculations, with high optimization efficiency and good convergence effect. Reactive capacity configuration of shore‐based power supply system for offshore production platform can reduce failure rate and life cycle cost.

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.

Review of Modulation Algorithms for Neutral-Point-Clamped Multilevel Converter

Many modulation techniques have been developed along the years to provide in medium and high-voltage converters a high power quality and minimum switching frequency. This paper introduces some popular modulation techniques for multilevel converters, whose major challenges are obtain the previous two features. The modulation strategies that are presented are specially focused in the three-phase three-level Neutral-Point-Clamped convert (NPC), which is one of the most used topology in industry and in renewable applications.

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.

An Intelligence-Based Controller for Improved Frequency Regulation in Deregulated Power Environment

A methodology for designing and assessing an optimal controller to regulate frequency in a two-area interconnected power system with Renewable Energy Sources (RES) is demonstrated in this paper. The Load Frequency Control (LFC) system makes it possible to restore both system frequency and scheduled tie-line power to their nominal values in a deregulated environment. The introduction of an advanced controller has the potential to improve the LFC mechanism's performance. The present article employs the Inertia Emulation Technique (IET) to demonstrate the potential influence of the novel High Voltage Direct Current (HVDC) tie-line model and converter capacitors. The Integral Time-weighted Absolute Error (ITAE) has been taken as an objective function for the proposed controller. This investigation proposes a novel adaptive control strategy i.e., ANN-based (PIλf + PIλDN) controller for the anticipated LFC mechanism. The modified Quasi-Opposition-learning-based Volleyball Premier League (QOVPL) method is utilized to assess the optimal control parameters with the highest efficacy. The effectiveness of the proposed LFC framework has been evaluated through the implementation of established methodologies for managing step and random load perturbations. The supremacy and effectiveness of the proposed control scheme are validated over recently published work.

Fault Location in Hybrid AC/DC Transmission Grids Containing DERs and HVDC Lines

This paper introduces a new fault location method for hybrid AC/DC complex transmission grids containing Distributed Energy Resources (DERs) and Modular Multilevel Converter-High Voltage Direct Current (HVDC) lines. Digital Fault Recorders (DFR) in the DC grid cannot observe faults occurring in the AC network and vice-versa. The proposed algorithm accurately locates faults irrespective of their location using a subset of DFRs selected by a K-means clustering method. The algorithm is tested using an AC/DC complex transmission network formed by merging the modified IEEE 39 bus transmission system and the CIGRE B4 DC grid test systems under several fault conditions using EMTP-RV and MATLAB as simulation tools.

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.

Defect Passivation and Lithium Ion Coordination Via Hole Transporting Layer Modification for High Performance Inorganic Perovskite Solar Cells.

Metal halide inorganic perovskite solar cells (PSCs) have great potential to achieve high efficiency with excellent thermal stability. However, the surface defect traps restrain the achievement of high open circuit voltage (VOC ) and power conversion efficiency (PCE) of the devices due to the severe nonradiative charge recombination. Moreover, the state-of-the-art hole transporting layer (HTL) significantly hampers device moisture stability, even though it renders the highest solar cell efficiency. Herein, a one-stone-two-birds strategy is proposed using a biocompatible material tryptamine (TA) as an additive in HTL. First, TA bearing electron rich moieties can favorably passivate the surface defects of inorganic perovskite films, significantly reducing trap density and prolonging charge lifetime. It results in a drastic improvement of VOC from 1.192 to 1.251V, with a VOC loss of 0.48V. The corresponding PSCs achieve a 21.8% PCE under 100mW cm-2 illumination. Second, TA in HTL can coordinate with lithium cations, retarding their reaction with moisture and increasing the moisture stability of HTL. Consequently, the black phase of inorganic perovskite films is well preserved, and the corresponding PSCs maintain 90% of the initial PCE after 800h storage at relative humidity of 25-35%, much higher than the control devices.

Reduced switch cascaded asymmetrical 27 level inverter-STATCOMwith fuzzy logic controller

<p>In this study, a 27-levelinverter with a reduced switch asymmetrical cascaded H-bridge (CHB) with fuzzy logic controller (FLC) is proposed. With series connections, a low voltage converter, a middle level voltage converter, and a high voltage converter make up the static synchronous compensator (STATCOM). The configuration of the asymmetrical inverter uses trinary DCsources. To acquire switching signals for the trinary inverter-based STATCOM to compensate for real power, load voltage, reactive power, load current, and power factor under load changing conditions, FLC is constructed. With fewer switches, the suggested arrangement produces greater voltage levels. The performance of the reduced switch asymmetrical cascaded H-bridge inverter-STATCOM with FLCis simulated using the MATLAB Simulink platform under both static and dynamic load conditions. When compared to reduced switch asymmetrical cascaded H-bridge inverter-STATCOM with traditional proportional integral (PI) controller, the FLC result demonstrates efficient unbalanced load compensation. The FLC in the proposed inverter also lowers the total harmonic distortion.</p>

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.

HEG-T2F: Hybrid Ebola Gannet-Based Type 2 Fuzzy-Based Controller for Modular Multilevel Converter

Modular multilevel converter (MMC) plays a significant part in high voltage power electronic industries due to its wide range of benefits such as modularity and reliability. The circulating component exists between three-phase half-bridge MMC causing certain issues in the design of MMC such as system loss, voltage instability, current disturbance, etc. To handle such problematical factors, a novel circulating current control mechanism named ‘hybrid ebola gannet based generalized type 2 fuzzy controller (HEG-GT2FC)’ is proposed in this paper. Here, the main controlling parameters of MMC namely harmonic distortion, current ripple, and circulating current settling time are adjusted or minimized using the generalized type 2 fuzzy controller. The hybrid ebola gannet algorithm solves the high voltage conversion problem by determining the optimal solution. The proposed HEG-GT2FC mechanism is evaluated using the MATLAB/Simulink tool. The performance of the proposed HEG-GT2FC mechanism is investigated in terms of measures such as current ripple, total harmonic distortion, and circulating current settling time. The simulation results illustrate that the proposed HEG-GT2FC mechanism achieves a very low percentage of current ripple (0.09%), total harmonic distortion (4.98%), and circulating current settling time (0.8 sec) than other compared state of art techniques.

Analysis of the sudden increase in dissolved acetylene content in oil of ultra high voltage converter transformer

Analysis of the sudden increase in dissolved acetylene content in oil of ultra high voltage converter transformer

Adaptive Active Inertia Control Strategy of MMC-HVDC Systems for Flexible Frequency Support

The Modular Multilevel Converter High Voltage Direct Current Transmission (MMC-HVDC) technology is considered to be the most feasible choice for high-voltage and high-power transmission systems, and its flexibility and high controllability provide a new solution for renewable energy grid integration. The MMC topology contains a large number of capacitors, which enables it to provide a certain active inertia support for the connected AC system. Different from a synchronous machine, the active inertia control of an MMC can flexibly adjust a system’s inertia-supporting power by changing the control parameters. By introducing a variation of the Sigmoid function with amplitude-limiting capability, this paper proposes an adaptive active inertia control strategy for the MMC-HVDC system. The proposed scheme adjusts the inertia constant adaptively according to the frequency change rate of the AC system, which can better respond to the frequency recovery performance. Finally, the MMC-HVDC simulation model is established in PSCAD/EMTDC to verify the effectiveness of the proposed control strategy.

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.

Switched inductor super boost converter with auxiliary charging mode for low duty operation in a DC microgrid

For a number of applications including the power processing of low voltage renewable sources such as solar PV in grid connected systems, high gain voltage conversion is a basic requisite. A conventional boost converter will have diode recovery issues, increased current ripples, poor transient response, and low efficiency if it is being operated at high duty ratio beyond certain permissible limit. This paper discusses a new converter suitable for the mentioned application that uses three double-duty regulated switches, switched inductor–capacitor to deliver the required high voltage at a low duty cycle. This converter’s basic topology does not include complex circuitry such as transformers, coupled inductors, and cascaded/interleaved configurations. In addition, the proposed converter can operate in auxiliary charging mode, which improves the voltage gain and control flexibility while also expanding the duty ratio range. The converter in discussion has a high voltage gain, a low total voltage standing, a continuous input current, a wide range of duty ratios, and the ability to select the duty cycle as needed. The boundary conditions, as well as the CCM and DCM investigations of the proposed converter are explored. The experiment findings are used to validate the claims made in the theoretical analysis. A comparison with the available high gain DC–DC converters is made to justify the superior performance. A 200 W prototype of the converter is developed and tested in laboratory to validate its feasibility and behavior for the renewable based applications.

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).

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.