High Voltage Ratio Research Articles

A Hybrid RBFNN-SPOA Technique for Multi-Source EV Power System with Single-Switch DC-DC Converter

With a single-switched DC-DC converter, a hybrid approach is proposed for a fast-charging (FC) dc to dc converter with the controller for an electric vehicle charging station (EVCS) that combines solar photovoltaic (PV), fuel cells (FC), and a battery energy storage system (BESS). The proposed hybrid technique integrates a radial-basis-function-neural-network (RBFNN) and a student-psychology-optimization-algorithm (SPOA); commonly known as the RBFNN-SPOA technique. The PV-FC hybrid electric vehicle systems, like controllers, electric vehicle, and the vehicle’s power source, are displayed. The proposed converter architectures have less voltage waveform changes, a low voltage stress on semiconductor power sources, and a high-voltage ratio of conversion. The proposed method is to use FC successfully at battery charge states and varied radiation levels. The FC in the controller of SPOA may change the inputs and outputs depending on the battery state of charge (SoC) and PV irradiation. Similarly, the needed input-torque for the motor is forecasted by the recalling recurrent neural network controller using several manually produced torque signals. The performance of the proposed technique is evaluated in MATLAB and is compared to ant colony optimization (ACO), crow optimization algorithm (COA), and fuzzy logic controller (FLC) approaches. According to the results, the efficiency of the proposed technique is 99.17%.

High ratio DC-DC converter based on cascade modified Cuk converter topology

The proposal of a modified Cuk converter as the basic cell in the cascade topology, namely the cascade modified Cuk converter, has been conducted. A scheme for increasing the high voltage ratio using a cascade topology with 3 cells has been obtained, namely by increasing the source voltage to the total output voltage which includes the 3 cells. This will provide a higher voltage ratio than DC-DC converters that do not use cascade topology. In this study, a drop voltage expression due to non-idealities is derived. The voltage losses in the cascade condition will be high if there is an increase in the number of levels. Calculations and simulations on the proposed converter have also been conducted where the optimal duty cycle value is obtained in ideal and non-ideal conditions and the output voltage in both conditions. Experimental results have been given where non-ideal conditions give output voltage results close to the calculation and simulation values so that the duty cycle value becomes a reference in the design of the closed loop control system. Power loss fraction and efficiency have also been given so that efficiency optimization in the cascade modified Cuk circuit can be done to get high efficiency. The proposed closed loop control system has also been given where the control system uses a double-loop control scheme, namely the inner circle for current control and the outer circle for voltage control. Simulations and experiments have been given on the closed loop control system. It is found that the closed loop control system is fast, adaptive, and responsive. The contributions in this paper are to provide the results of simulation and experimental calculations, perform power loss analysis, propose a closed loop control system on the cascade topology, and provide expected results.

Dual-Coupled-Inductor-Based High-Step-Up Boost Converter with Active-Clamping and Zero-Voltage Switching

Many applications, such as photovoltaic systems, uninterruptible power supplies, and automobile headlamps, need a high step-up DC–DC converter without isolation. The conventional boost converter has the advantages of simple topology and easy control. However, it has some shortcomings, such as insufficient step-up voltage ratio and poor efficiency when operating at large duty-cycle conditions. One of the popular topologies used to overcome these problems is the coupled-inductor boost converter. It utilizes the turn ratio of the coupled inductor to realize a higher step-up voltage ratio. The drawback is that the leakage inductance of the coupled inductor causes a huge voltage spike when the power switches are turned off. Moreover, because coupled inductors are characterized by their large volume and high profile, a conventional coupled-inductor boost converter is unsuited for photovoltaic systems, such as the solar microinverter. This study proposes a novel high-step-up boost converter to solve these problems. This proposed converter uses dual coupled inductors instead of the conventional coupled-inductor boost converter. The secondary side of the coupled inductor is connected in series to increase the step-up voltage ratio. The proposed converter utilizes active clamping to achieve zero-voltage switching (ZVS) for suppressing voltage spike and improving conversion efficiency. In addition, low-profile designs can be fulfilled easily for solar microinverters. The proposed converter and its control method are introduced. The operation principle, circuit characteristics, and circuit analysis are presented. A prototype converter with 300 W output power 25–40 VDC input voltage and 200 VDC output voltage was tested. All functions, including high step-up voltage ratio, ZVS, and active clamping, were achieved, and the highest efficiency was around at 94.7%.

Switched-Capacitor Enhanced Circuits for Voltage-Boosting DC-DC Converters: Principles and Applications

With rapid advancement of DC-DC converter, the non-isolated dc-dc converters has caught much attention from academia and industry, owing to its advantages including low cost and compacted structure. Especially, the non-isolated dc-dc converters have taken the dominant position in topology design of power source. This paper introduces the concept of output section evolution in non-isolated dc-dc converters, with the aim of integrating high ratio voltage boosting capacity. To achieve this, a series of novel output enhanced circuits are proposed and discussed in detail. These circuits are structured using capacitors and diodes, making them applicable to various positive output dc-dc converters. Notably, the derived topologies in this paper eliminate the need for additional power switches and transformers. The effectiveness of the proposed approach is demonstrated through application cases based on both the classical boost converter and the developed voltage-lift SEPIC converters. These cases showcase the practical application and benefits of the proposed method. By following the topology construction method outlined in the paper, engineers can gain valuable insights and guidelines for designing circuits in the field of power electronics. Theoretical analysis has been verified in experimental prototype and the provided resources also serve as an educational tool for those studying power electronics engineering.

Improved Sliding Mode-Based Controller of a High Voltage Ratio DC–DC Converter for Electrolyzers Supplied by Renewable Energy

Improved Sliding Mode-Based Controller of a High Voltage Ratio DC–DC Converter for Electrolyzers Supplied by Renewable Energy

Characteristics of high-repetition-rate bipolar pulse DBD under various electrical conditions in atmospheric-pressure air

Numerous studies have been conducted on pulse dielectric barrier discharge (DBD) because it can produce powerful discharges uniformly at atmospheric pressure with a fast rise time. Although much research has been conducted on pulse DBD below 10 kHz, relatively little has been conducted on pulse DBD at high pulse repetition rates (PRRs). Therefore, in this study, the ozone generation and discharge characteristics of bipolar pulse DBD in atmospheric-pressure air at a high PRR of 10 kHz or above were investigated. According to the results of this study, with the exception of electron temperature, most discharge characteristics need for practical applications—like transfer charge, electron density, and discharge uniformity—improved as the voltage and duty ratio increased at high PRR. On the contrary, increasing the PRR exhibited trade-off features like low electron temperature, low discharge uniformity, and a high number of discharges per unit time. Ozone generation demonstrated good results at high voltage, appropriate PRR, and low duty ratio, but applying suitable electrical conditions is crucial considering ozone generation speed and power consumption. The findings of this study will be very beneficial for high-PRR pulse DBD applications that require quick and effective processing. Additionally, they will be useful for researching the characteristics of pulse DBD at high PRR.

A bidirectional high voltage ratio DC–DC topology for energy storage systems in microgrid

AbstractThis study proposes a bidirectional DC–DC converter with low voltage stress on its semiconductor elements and high voltage gain. Bidirectional DC–DC converters play a crucial role in DC microgrid systems, and they have been used for many applications such as power flow management, battery storage systems, voltage regulation, and electric vehicle (EV) charging systems. This paper proposes a novel non‐isolated, bidirectional DC–DC converter with an improved voltage gain conversion ratio. In the structure of the proposed converter, the coupled inductor provides high voltage gain and is employed to reduce the overall voltage stress across the main switches. Additionally, a filter inductor on the input‐low voltage side of the converter reduces current ripple. In addition, a single switch is used in boost mode, which simplifies control of the converter. Furthermore, two power switches receive simultaneous pulses for adjusting the buck stage voltage gain. Also, in the following, the mathematical calculations and the small signal analysis for the proposed converter are provided. Furthermore, a 200 W prototype is finally implemented, and its results are validated by the theoretical analysis.

Torque ripples enhancement of a PMBLDC motor propelled through quadratic DC–DC boost converter at varying load

The characteristic effects of a permanent magnet brushless dc (PMBLDC) motor which is propelled by a quadratic DC–DC boost converter was investigated in this paper. The boost converter applied inductor coupling with semi-conductor switches which operate concurrently to produce a high conversion voltage ratio. Modeling of the PMBLDC motor was presented while simulation was performed using a closed loop control system with different controllers for the enhancement of torque–speed performance at varied load. Simulation results show that an optimum voltage gain with minimum voltage stress was achieved at 0.9 duty cycle while varying the inductor turns ratio (n) from 1 to 6 and inductor coupling coefficient (K) from 0.1 to 1.0 so as to ensure that the entire flux generated in one coil is fully linked to the other. A simplified PI controller was designed and experimented through simulation for excellent drive performance at varying load. The results from the spectral display show that the usual speed oscillation and torque ripples produced by the machine were attenuated using different speed controllers. The Total Harmonic Distortion (THD) values indicate that the PID controller achieved a minimal value of 24.06% for speed and 23.16% for torque as compared to 28.73% and 29.82% obtained from the PI controller, while the P controller achieved 41.88% and 35.67% as shown in the graphical abstract.

Design of a bidirectional converter for charging/discharging a supercapacitor

This article presents the analysis and design of a new converter that combines the current doubler topology and the parallel converter to achieve greater stability and effective reduction of ripple in both voltage and current parameters. Basically, the DC-DC (Direct Current to Direct Current) converter operates with pulse modulators to control the current in the desired charging or discharging direction. Extensive simulations were carried out at nominal values of 48 V and 8.5 A of output, and 100 V of input to confirm the performance of this converter. The approach used has benefits in terms of safety, reduced electrical noise, practical implementation for interconnecting energy sources with high voltage ratios, and increased lifespan of supercapacitors as well as batteries. Simulation results are presented and the advantages and applications of this new configuration are discussed.

Design and prototyping of transformerless DC-DC converter with high voltage ratio for MVDC applications

Power boost DC-DC voltage converters have become a key element for medium-voltage DC (MVDC) applications as a link between generation and distribution grids, it is possible to classify the DC-DC converters into four families, depending on their characteristics, as well, one of the actual principal needs is to reduce the number of passive and active components needed for voltage conversions. This article presents a novel transformerles DC-DC boost-resonant converter, which is destined for the interconnection of medium and high voltage DC smart grids. The proposed DC-DC converter is composed of two inductors, a capacitor, and five IGBTs interrupters, which are responsible for the interaction between resonant and boost converters, in the same way, the resonant converter is composed of one resonant inductor and one resonant capacitor while the boost converter is composed by one boost inductor. This paper also presents the operation principle of the proposed converter, as well as its control, modular connection, and simulation to probe the behavior of the converter and an experimental 100 W prototype with 9.5 gain.

Non-Isolated Power Factor Corrected AC/DC Converter with High Step-Down Voltage Ratio for Low-Power Applications

This paper proposes a high step-down ratio AC-DC converter employing a quadratic buck converter with power factor correction. Conventional active power factor correction topologies employ boost-based correction schemes for unity power factor operation. This will require a steeper step-down ratio and higher switch voltage stress apart from complexity in the control scheme with sensors. The structure of the proposed topology is developed by combining the power factor correction stage with a high step-down stage. The passive input filter is split up into two for the purpose of reducing the thermal heating apart from offering a higher power factor. A single switch operation reduces the complexity of the control scheme. In addition, the number of conducting devices during the current path is also the same as the conventional buck converter due to cascading and hence offers lower conduction losses. The need for the converter to operate at an extremely low duty cycle is reduced due to the quadratic stage structure. The proposed converter operates at a moderate duty cycle, offering higher step-down voltage apart from reducing filtering requirements. MATLAB R2020b is used for carrying out simulation studies. Xilinx FPGA-based controller using system generator is implemented for the generation of pulses of appropriate duty cycle. Simulation and experimental results for a 150 W prototype are presented. An investigation and comparative evaluation of the conventional bridgeless buck system with the quadratic buck converter are carried out. The proposed structure offers the benefit of a higher step-down voltage ratio incorporating an inherent power factor correction stage along with the AC/DC stage.

Two-Stage Step-up Converter with Different Voltage TransformationRatios depending on the Duty Cycle

A two-stage converter with high output voltage ratio and reduced current stress of the inductors and partly reduced voltage stress is discussed. The function is explained with the help of voltage and current diagrams. The voltage transformation ratio changes between a quadratic step-up for duty cycles lower 0.5 and a double Boost converter for duty cycles higher than 0.5. Dimensioning hints, the control law for feed-forward controls, the transient when the supply is turned on is discussed and some simulations are given. A comparison to other two-stage converters is also treated.

Design and Optimization of a Wireless Power Transfer System with a High Voltage Transfer Ratio

With the development of the logistics industry, low-voltage systems, such as intelligent logistics vehicles, have also started to propose application scenarios for wireless power transfer systems. As most logistics vehicles use lithium batteries for energy supply, the wireless charging system has to adapt to the charging characteristic curve of lithium batteries. In this paper, a dual-transmitter single-receiver compound resonant compensation topology with a high voltage ratio is proposed, and a corresponding magnetic coupler is designed and optimized through finite element analysis, which guarantees adaptive output curves according to the working state. A 1 kW experimental platform is established to verify the theoretical analysis, which realizes a high voltage transformation ratio with 90.3% efficiency. Throughout the whole charging process, the output curve agrees with the charging profile of the lithium battery, which can greatly extend the service life of lithium batteries.

A New FL-MPPT High Voltage DC-DC Converter for PV Solar Application

To reduce the effects of global warming, there is an increasing need for renewable energy sources. Several studies have been carried out on photovoltaic (PV) systems to maximize their potential as an alternative electricity generator. However, various power converters for high voltage ratio applications have multiple drawbacks. This research was carried out to develop a power converter topology connected between the PV and the load for the need. In this research, the high step-up DC-DC converter for high-voltage gain conversion ratio and high efficiency is proposed. Furthermore, the fuzzy logic-based Maximum Power Point Tracking (MPPT) technique connected to the power converter was used to maximize the power converted from PV in changing atmospheric conditions. The MPPT control with fuzzy logic controller (FLC) was analysed and compared with the perturb and observe (P&O) algorithm. The results showed that the FLC algorithm could control the high step-up (HSU) DC-DC converter with an output voltage of 29% higher than the P&O algorithm.

Study of the front-end signal for the 3-inch PMTs instrumentation in JUNO

A total of 25,600 3-inch PMTs will be installed in Jiangmen Underground Neutrino Observatory (JUNO) to achieve more precise energy calibration and to extend the physics detection potential. Performances of all bare PMTs have been characterized and these PMTs are being instrumented with the high voltage divider, underwater front-end cable, and connector. In this paper, we present a dedicated study on signal quality at different stages of the instrumentation. An optimized high voltage ratio was confirmed and finalized which improved the PMT transit time spread by 25%. The signal charge was attenuated by 22.5% (13.0%) in the 10 m (5 m) cable and it required the addition of 45 V (23 V) to compensate for the loss of PMT gain. There was a 1% overshoot following the PMT signal and no sign of reflection in the connector. A group of 16 3-inch PMTs with the full instrumentation was installed in the JUNO prototype detector together with a few 8-inch and 20-inch PMTs, which showed good stability and demonstrated a photon detection system with multiple types of PMTs.

Analysis and implementation of an interleaved high step‐up converter with reduced voltage stress an interleaved high step‐up DC‐DC converter with ZVS

AbstractA new symmetrical structure of the interleaved converter type is proposed in this paper to obtain high voltage gain. The proposed converter delivers a very high voltage ratio using the coupled inductor technique and switched capacitor, and all this happens at a moderate duty cycle. Furthermore, the MOSFETs have low voltage stresses. Therefore, MOSFETs with low conductivity resistance can be used to reduce the conduction losses. The input current has a small ripple because the input side uses the interleaved operation. Furthermore, zero‐current‐switching (ZCS) is obtained for MOSFETs, and the problem of reverse‐recovery for diodes is confined. Moreover, the passive clamp circuit recycles the energy of the leakage inductances which avoids high voltage spikes across the switches. Performance of the proposed converter along with the small‐signal analysis is discussed in detail. Finally, a laboratory prototype is developed with 30 V input and 400 V output to verify the proposed converter.

Comparative study of the design and simulation of an AC to high DC voltage generation circuit

Decades after the invention of the Cockcroft–Walton voltage multiplier, it is still being used in broad range of high voltage and ac to dc applications. High voltage ratio and high efficiency are its main features. Due to the limitations of original circuit, reducing the output ripple and increasing the accessible voltage level motivated scientists to propose new topologies. However, over the worldwide bibliography, most of Cockcroft-Walton voltage designers persist in using equal capacitances in every stage without considering an optimal design. The aim of this paper is to do a comparative study of the design and simulation of a fixed model (conventional model used by most authors) and a variable model (new design) of generating High Voltage Direct Current (HVDC) based on Cockcroft–Walton voltage multiplier that stresses on the choice of the adequate capacitance values to reduce the output voltage drop, produce less ripple and the calculations of the optimal number of stages that is necessary to produce the desired output voltage with a better performance. The generation of HVDC based on Cockcroft–Walton voltage multiplier and an eight stage was used for simulations and theoretical analysis which yielded up to 4.4 kV DC from an input voltage of 230 V, 50 Hz ac supply. The results are compiled from the simulations done on MATLAB/SIMULINK, by the designs and simulations characteristics of the models the performances, output voltages and ripple voltages per stage have been compared.

Dual Active Bridge Based Reduced Stage Multiport DC/AC Converter for PV-Battery Systems

Standalone power systems are significant for electrifying the remote areas where extending the grid connectivity is not feasible, either economically or logistically. Solar Photovoltaic (PV) systems with battery backup are among the most popular candidates to serve as an energy source in standalone systems. This article presents a novel multiport converter (MPC) for PV-battery systems powering standalone loads. The proposed converter is a reduced stage power converter based on current fed dual active bridge (CF-DAB) topology. CF-DAB offers galvanic isolation and a high voltage ratio without sacrificing efficiency. Switching losses are further reduced by a modified modulation scheme that reduces the average switching frequency of some of the switches. The proposed converter performs the functions of tracking maximum power point of the solar panel and regulating the load voltage while using fewer power conversion stages. This is done by sharing components among the various stages performing maximum power point tracking, voltage boosting, and dc/ac conversion. A small-signal model of the proposed MPC required for its closed-loop control is also proposed, which can also be utilized for other CF-DAB-based converters. A lab prototype of the proposed MPC has been fabricated and its operation has been validated under various static and dynamic conditions.

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.

Photovoltaic Power Plant Collection and Connection to HVDC Grid with High Voltage DC/DC Converter

Photovoltaic (PV) power plant collection and connection to a high voltage direct current (HVDC) grid has many advantages. Compared with the traditional AC collection and grid-connection scheme, it can reduce the power conversion links and improve the system efficiency. As one of the most important devices in the application of a PV HVDC collection and grid-connection system, a high voltage, large capacity, high step-up ratio DC/DC converter is the critical technology. A DC/DC converter scheme based on a boost full bridge isolated power module cascaded in input parallel output series (IPOS) structure is proposed to meet the technical requirements of PV power conversion with high voltage, large capacity, and high step-up ratio. The operation mode of the power module is analyzed, the soft switching method is proposed, and the constraint to realize the soft switching of the power module is deduced. Aiming to resolve the problem of multi-module voltage and current equalization in a cascaded DC/DC converter, a distributed module equalization control strategy is proposed to realize the reliable operation of a power module and converter. A 5 kV/80 kW standard power module is developed, the DC/DC converter experimental platform is built, and the proposed system scheme and control strategy are verified by experiments. Based on a 14-power module input parallel output series connection, a ±30 kV/1 MW PV DC/DC converter is developed, a ±30 kV PV HVDC collection and grid-connection demonstration system is established, and the experimental test is completed to realize the stable operation of the system.