Direct Current Converter Research Articles

Energy Efficiency Evaluation of HVDC Converter Station Based on Deep Neural Network Model

Abstract This paper introduces a new idea of energy efficiency evaluation of high voltage direct current (HVDC) converter based on deep neural networks. This paper analyzes the leading operating indicators and finds the main influencing factors in constructing the energy-saving hands of each converter table. Then this paper uses the deep neural network method to establish the converter table's energy efficiency model. The deep neural network for energy efficiency evaluation of the converter table is obtained. In this paper, PSCAD/EMTDC was used for simulation to evaluate the energy-saving effect. The research shows that the method of energy efficiency evaluation based on deep neural networks is feasible.

LTCC-Based DC-DC Converter for Reduction of Switching Noise and Radiated Emissions

In this study, a low-temperature co-fired ceramic (LTCC)-based direct current (DC)-DC converter is proposed for reducing stray inductance and mitigating electromagnetic interference. The dominant radiating loop of the proposed LTCC-based DC-DC converter features a multilayer design, which helps suppress noise sources and reduce radiated emissions. The peak voltage of switching noise for the proposed DC-DC converter at the frequency of 500 kHz is approximately 8.98% lower than that of a conventional DC-DC converter. In addition, the radiated emission level of the proposed DC-DC converter is lower than that of the conventional DC-DC converter. In sum, the proposed LTCC-technology-based multilayer design reduces the peak voltage of switching noise and the radiated emission of the DC-DC converter.

Case study on fire resistance of fire stopping system in Ultrahigh-voltage Direct current converter station

In this study, two existing fire stopping systems of the valve hall in the converter station were selected, and the heat transfer process in the key areas was simulated by the ANSYS software under the condition of a hydrocarbon temperature rise curve. The main thermal parameters, such as temperature field, thermal flux, and thermal gradient, were obtained, and the temperature rise characteristics of measuring points were tested through the Fire Test Furnace and the one-dimensional heat conduction model. The simulation results show that Model 2 exhibits superior thermal resistance performance compared to Model 1, and the maximum heat flux density occurs at the square steel (keel) position. During the fire resistance test, it is observed that the fireproof mortar at the connection of Autoclaved Lightweight Concrete board in Model 1 exhibits significant detachment and cracking, accompanied by the emission of white smoke. Compared with the temperature rise of the measuring points in Model 1 and Model 2, the heating rate of measuring points f1 and f2 is 0.0471 °C/s and 0.0159 °C/s, respectively. The temperature value obtained from the fire resistance test exceeds that calculated by the one-dimensional heat conduction model.

Operating characteristics of a linear range extender with different energy consumption topologies

The free-piston linear generator is a new energy transformation technology with compact structure, multi-fuel adaptability, low friction loss, and simple modular configuration. To advance the practical process of the free-piston linear generator, several different topologies of electrical energy consumption are applied to the system, and the generating performance of the system is investigated in three-phase resistive load topology, uncontrolled rectification-resistive load topology, uncontrolled rectification-battery topology, and uncontrolled rectification-direct current to direct current converter -battery topology. The influence of the different topologies on the generator is mainly in the output type and output power (periodic, fluctuating). Furthermore, the impact of the topology on the operating characteristics of the free-piston linear generator, which mainly brings about changes in the characteristics of the current amplitude current fluctuations and generator force near the dead center, is explored. The current amplitude can influence the frequency and damp properties significantly and may cause system shutdown because of the improper matching of the generator and the load terminal. Changes in the generator force in the low-velocity region near the dead center have less impact on the output and thermodynamic processes of the system. The impact on system performance increases as the changes expand to the high-velocity region.

Advanced DC–DC converter topologies for solar energy harvesting applications: a review

Abstract In this study, the advanced topologies of a DC–DC converter for applications involving the harvesting of solar energy are discussed. This work’s primary contribution is a guide for choosing the most effective topology for a DC–DC converter when developing solar energy collection systems. Several topologies of a DC–DC converter for solar energy harvesting applications are compared in terms of the range of power levels they can oversee, the complexity of the underlying hardware, the cost of implementation, the tracking efficiency and the overall efficiency of the converter. This article explains five innovative approaches for adapting boost converters to function as standard DC–DC converters to capture solar energy, consisting of (i) voltage-multiplier cell, (2) coupled inductor, (3) coupled inductor and switch capacitor, (4) cascaded topology and (5) voltage-lift technique. Because of the boost converter’s restrictions, it is necessary to deliver high performance. The comparison findings demonstrate that the voltage-lift-based boost-converter topology performs more effectively than the alternatives. In conclusion, the information presented in this paper can be utilized when developing solar energy collection systems to determine the sort of direct current to direct current converter that will be most effective.

Low-cost portable throttle curve manipulator for smooth initial movement of an electric vehicle

This research aims to develop a low-cost portable throttle curve manipulator for a smooth initial movement of an electric vehicle. The hardware is mostly made up of an Arduino and a pulse width modulation (PWM)-to- direct current (DC) converter, which can be easily installed in electric vehicle. The manipulator produces a throttle output curve based on the current throttle input. The suitable throttle output curve is investigated in two stages. First, the four throttle curve types are compared based on motor vibration change and total energy usage during initial movement. They are none, linear, exponential, and polynomial curve types with a delay of 1 s. Then, in the second stage, the delay is varied from 0.5 to 2.5 s. The result shows that the linear throttle curve output with a delay of 1 s produces is appropriate to refine the initial movement of an electric vehicle compared to the polynomial and exponential curve types. The brushless DC electric (BLDC) motor vibration change decreases from 148.75 Hz to 107.45 Hz and total energy usage decreases from 90.64 joules to 87.23 joules. Therefore, the research concludes that the low-cost portable throttle curve manipulator can be developed using a linear throttle output curve with a delay of 1 s.

A high-efficiency transformer-in-package isolated DC-DC converter using glass-based fan-out wafer-level packaging

A transformer-in-package (TiP) isolated direct current–direct current (DC-DC) converter using glass-based fan-out wafer-level packaging (FOWLP) is proposed. By using 3-layer redistribution layers (RDLs), both the transformer and interconnections are built without an additional transformer chip, and the converter only has 2 dies: a transmitter (TX) chip and a receiver (RX) chip. The proposed solution results in a significant reduction in the cost and makes major improvements in the form factor and power density. Moreover, the transformer built by the RDLs achieves a high quality factor (Q) and high coupling factor (k), and the efficiency of the converter is thus improved. The TX and RX chips were implemented in a 0.18 µm Biopolar CMOS DMOS (BCD) process and embedded in a compact package with a size of 5 mm × 5 mm. With an output capacitance of 10 µF, the converter achieves a peak efficiency of 46.5% at 0.3 W output power and a maximum delivery power of 1.25 W, achieving a maximum power density of 50 mW/mm2.

Comprehensive Analysis and Experiment of Extreme Faults in MMC Based on IGCT

High voltage direct current voltage source converter (HVDC-VSC) technology is one of most important solutions for transmission of large-scale renewable sources. Modular multilevel converter (MMC) is one of the most popular topologies for HVDC-VSC system. The extreme faults affect the safety and reliability of MMC greatly. This paper gives comprehensive analysis and experiment of extreme faults in MMC based on integrated gate commutated thyristor (IGCT). Causes and characterization of the extreme faults are analyzed in detail. A new protection solution based on IGCT with controlled punch-through design (CP-IGCT) and fast recovery diode with high surge current capability (HS-FRD) is proposed. The surge current capability of HS-FRD is validated via experiment successfully. Theoretical calculation shows that the protection solution based on CP-IGCT and HS-FRD can help reduce the maximum fault current below 50% when the anode inductor is 0.8 μH in the extreme shoot-through fault. Test results show that the protection solution can realize the discharge of the DC capacitor below 4.5 kV in the extreme shoot-through fault. The maximum fault current in MMC based on IGCT is only about 600 kA while the maximum fault current in MMC based on insulated gate bipolar transistor (IGBT) is over 1100 kA. Explosion proof of CP-IGCT is validated during the tests, which is similar to that of the protection thyristor. However, IGBT can't guarantee the stability of the package and may cause severe safety problem. The failed CP-IGCT has the short circuit failure mode (SCFM) and can be used for bypass of the faulty MMC sub-module (MMC-SM). Via comparison, the proposed protection solution has lowest cost and complexity, as well as the highest safety.

Reducing heat generation in a boost inductor using a magnetic tape

Increasing the switching frequency of direct current–direct current converters is effective in reducing the size of magnetic components used in converters. However, as the switching frequency increases, the loss and heat generated by the magnetic components increase. Therefore, in this study, a magnetic tape that bypasses the magnetic flux in the windings of magnetic components is proposed to reduce the loss and heat generation of these components. The effect of suppressing the temperature rise of magnetic components with a magnetic tape during the converter drive was investigated. The temperature rise of a 1-MHz 100-V/200-V 800-W boost inductor was reduced by 16.8 K by applying the magnetic tape. Additionally, applying the magnetic tape to the inductor reduced the heat generation.

Design and simulation of Arduino Nano controlled DC-DC converters for low and medium power applications

<p>This paper mainly focuses on the controller of portable direct current to direct current (DC-DC) converter which may be simple, low cost and efficient. Nowadays, proportional integral (PI) controller and opto-isolator based circuits are used for switching control. The switching control through the controller makes the DC-DC converter into larger circuit and less efficient. This problem will be rectified using the Arduino Nano controller which is small and low cost-effective controller. It is useful for low and medium power applications like residential solar power system, electronic gadgets, and academic laboratories. Arduino Nano-based DC chopper has been developed, and the Proteus software used for simulation. The different topologies of DC choppers like buck, boost, and buck-boost converter have been designed with mathematical calculations and simulated.</p>

A novel fuzzy logic control for a zero current switching-based buck converter to mitigate conducted electromagnetic interference

<span lang="EN-US">This research provides a new control technique for mitigating conducted electromagnetic interference (EMI) in a buck converter designed for solar applications. Indeed, hard-switching direct current to direct current (DC-DC) converters, commonly used in industrial applications, pose a significant risk to the surrounding environment regarding electromagnetic compatibility (EMC). Usually, the fast-switching phase induces abrupt changes in current and voltage, which adds to substantial electromagnetic interference in both conducted and radiated modes and excessive auditory noise. An architecture based on the duality of soft-switching topology and fuzzy logic control technology is developed to address these issues. On the one hand, resonant circuit topologies are used to induce switches to achieve soft switching conditions, which subsequently lessen the effects of EMI. On the other hand, the adoption of fuzzy logic control technology is interesting since it can reduce electrical stresses during switching. Furthermore, the simulation results show that zero current switching (ZCS) soft-switching closed-loop fuzzy logic converters outperform typical open-loop converters and soft-switching closed-loop converters with proportional integral (PI) control in terms of EMC requirements.</span>

Fuzzy Control of a High-Performance Boost Converter in Discontinuous Conduction Mode and its Application to a Photovoltaic Pumping System

In this work, a fuzzy voltage controller design of a 1 kW high-gain, high-efficiency direct current converter operating in discontinuous conduction mode is developed. In this condition, the design of a conventional controller is more challenging. This converter is part of an autonomous photovoltaic pumping system without batteries consisting of four photovoltaic modules, a variable frequency inverter and an induction motor coupled to a pump. The boost converter is responsible for the voltage elevation of photovoltaic modules to a 311V direct current bus, which must not have oscillations for a good operation of an algorithm to track the maximum power point of the modules. The fuzzy controller was implemented in a digital signal processor device to control the boost converter, producing a response with an overshoot of 5.78%, settling time of 3.8s and zero error in steady state.

State-of-health diagnosis of lithium-ion batteries using the fractional-order electrochemical impedance model

The rapid growth of the battery industry has encouraged manufacturers to develop suitable materials that provide maximum safety for their products and customers, evaluate the product's shelf life before marketing, and recycle waste products to preserve the environment. This study presented a new aging diagnosis method using harmonic analysis combined with a fractional-order impedance model (FOIM) to monitor the aging and state-of-charge (SoCs) of lithium-ion batteries (LIBs). The proposed model showed reasonably good accuracy with experimental results from the literature, with a mean squared error (MSE) and a mean absolute percentage error (MAPE) of less than 2% and 0.2%, respectively. On the other hand, to understand the aging patterns and to establish the aging laws incorporated into the simulation models, the FOIM of the LIBs was connected in series with both a pulse-width-modulated (PWM)-controlled direct current (DC/DC) converter and the load to monitor the aging of the LIBs. The harmonic analysis of the acquired current signal enabled the measurement of frequency spectrum amplitude (FSA) variations at low (50 Hz) and high (1000 Hz) frequencies in different ages and SoCs of the LIBs operation. Additionally, the proposed diagnostic technique confirmed that the harmonic signatures indicated differences between different ages and the SoCs of the battery.

Two-layer energy management strategy for renewable power-to-gas system-based microgrids

This study proposes a two-layer energy management system for the power-to-gas system-based microgrid. One layer is a supervisory control based on fuzzy logic, which optimally distributes the power among different system components, such as fuel cells and an electrolyzer. The second layer consists of power converters, such as direct current (DC)-DC converters and inverters, which generate power in accordance with the supervisory layer. The main contribution of the present study is to investigate the dynamic performance of the coordinated control between two layers by the proposed control strategy. The proposed controller is validated by hardware-in-the-loop experiments. Results show that the proposed controller is effective in stabilizing the DC bus voltage and ensuring power balance in the microgrid by optimally distributing the power among the fuel cells, electrolyzer, and grid. A comparative analysis between the proposed EMS and other benchmark strategies is also performed. The proposed strategy is found to handle power transients for electrolyzer and fuel cell components better than the rule-based strategy. However, the proposed strategy provides similar performance as compared to model predictive control.

FUZZY LOGIC CONTROL TO PROCESS CHANGE IRRADIATION AND TEMPERATURE IN THE SOLAR CELL BY CONTROLLING FOR MAXIMUM POWER POINT

This paper presents intelligent control methods to get the maximum power point (MPPT) to be a photovoltaic system that operates with high efficiency when weather conditions change as well as fluctuations in temperatures resulting from sunlight. The proposed method of controlling by fuzzy control techniques is applied with a Direct current to Direct current (DC-DC) converter device. The important steps of the control unit for integrated design. The photovoltaic system, which was designed by Matlab / Simulink, was implemented with simulations of autonomous water pumping techniques. Comparison of results with simulations without MPPT control. We have noticed that the system in the case of using the MPPT that was used in the fuzzy logic unit gave high efficiency for the energy production from the solar cell the crucial control unit steps for integrated design. Simulated autonomous water pumping methods were used to implement the Matlab/Simulink-designed photovoltaic system. Results comparison with simulations lacking MPPT control. We have observed that the system provided great efficiency for the energy generation from the solar cell in the event of using the MPPT that was used in the fuzzy logic unit.

DC-Link Capacitor Optimization in AC–DC Converter by Load Current Prediction

Alternating Current–Direct Current (AC–DC) converters require a high value bulk capacitor or a filter capacitor between the DC–DC conversion stages, which in turn causes many problems in the design of a AC–DC converter. The component package size for this capacitor is large due to its high voltage rating and capacitance value. In addition, the high charging current creates more problems during the product compliance testing phase. The shelf life of these specific high value capacitors is less than that of Multilayer Ceramic Capacitors (MLCC), which limits its use for the highly reliable applications. This paper presents a feasibility study to overcome these two problems by adding a few sensing mechanisms to the typical AC–DC converter topology. In majority of the AC–DC converter, Al-Elko capacitor takes approximately 3% to 5% of the converter size. The proposed method reduces this to approximately 50% size and so it effectively approximates 2% to 3% size reduction in converter size. The proposed method basically works based on the load current prediction method and hence it is highly suitable for the constant load application. Moreover, the converter response time increases in this method, which limit its application in high-speed systems. The high temperature application of Al-Elko capacitor is limited because of its poor performance, which is significantly rectified by replacing the Al-Elko with MLCC as it delivers good performance in high temperature.

Deep Learning-Based FOPID Controller for Cascaded DC-DC Converters

Smart grids and their technologies transform the traditional electric grids to assure safe, secure, cost-effective, and reliable power transmission. Non-linear phenomena in power systems, such as voltage collapse and oscillatory phenomena, can be investigated by chaos theory. Recently, renewable energy resources, such as wind turbines, and solar photovoltaic (PV) arrays, have been widely used for electric power generation. The design of the controller for the direct Current (DC) converter in a PV system is performed based on the linearized model at an appropriate operating point. However, these operating points are ever-changing in a PV system, and the design of the controller is usually accomplished based on a low irradiance level. This study designs a fractional-order proportional-integrated-derivative (FOPID) controller using deep learning (DL) with quasi-oppositional Archimedes Optimization algorithm (FOPID-QOAOA) for cascaded DC-DC converters in micro-grid applications. The presented FOPID-QOAOA model is designed to enhance the overall efficiency of the cascaded DC-DC boost converter. In addition, the proposed model develops a FOPID controller using a stacked sparse autoencoder (SSAE) model to regulate the converter output voltage. To tune the hyper-parameters related to the SSAE model, the QOAOA is derived by the including of the quasi-oppositional based learning (QOBL) with traditional AOA. Moreover, an objective function with the including of the integral of time multiplied by squared error (ITSE) is considered in this study. For validating the efficiency of the FOPID-QOAOA method, a sequence of simulations was performed under distinct aspects. A comparative study on cascaded buck and boost converters is carried out to authenticate the effectiveness and performance of the designed techniques.

Fuzzy Based Interleaved Step-up Converter for Electric Vehicle

This work focuses on the fuzzy controller for the proposed three-phase interleaved Step-up converter (ISC). The fuzzy controller for the proposed ISC converters for electric vehicles has been discussed in detail. The proposed ISC direct current (DC-DC) converter could also be used in automobiles, satellites, industries, and propulsion. To enhance voltage gain, the proposed ISC Converter combines boost converter and interleaved converter (IC). This design also reduces the number of switches. As a result, ISC converter switching losses are reduced. The proposed ISC Converter topology can produce a 143 V output voltage and 1 kW of power. Due to the high voltage gain of this converter design, it is suitable for medium and high-power systems. The proposed ISC Converter topology is simulated in MATLAB/Simulink. The simulated output displays a high output voltage. But the output voltage contains maximum ripples. Fuzzy proposes an ISC Converter which makes closed loop responsiveness and reduces the output voltage ripple. The proposed ISC converter has the lowest ripple output voltage, which is less than 2%, because the duty cycle is regulated using the fuzzy logic controller. It offers high voltage gain, minimal ripple, and low switching loss. The performance of the proposed converter is compared to that of the fuzzy and Proportional Integral (PI) controllers implemented in MATLAB.

Space Charge Characteristics of Natural Ester Oil-Impregnated Paper With Different Moisture Contents

Mineral oil is the most common dielectric liquid for high-voltage direct current (HVDC) converter transformers. However, natural ester oil receives much attention as an alternative dielectric liquid due to its environmental friendliness and low fire risk. Moisture is one of the most dangerous substances, which accelerates the degradation of oil-paper insulation systems. Thus, this article investigates the impact of moisture on space charge characteristics of the natural ester oil-impregnated paper by comparing it with the mineral oil-impregnated paper. Space charge accumulation is a typical phenomenon under dc conditions, and its presence can lead to electric field distortion and accelerate insulation aging. The space charge profiles in oil-impregnated papers with different moisture contents are obtained by the pulsed electroacoustic (PEA) method. It has been found that the hydrophilic characteristic of natural ester oil leads to a slow process of forming heterocharges in the natural ester oil-impregnated paper. On the other hand, the hydrophobic characteristic of mineral oil results in faster heterocharge formation in the mineral oil-impregnated paper.

A new high step‐up DC power supply with modular switched capacitor cells

AbstractIn this paper, a novel high step‐up direct current (DC)‐DC converter, using switched‐capacitor (SC) cells, is proposed. Upon turning a set of switches in this converter on/off, the capacitors are connected to each other in a circuit configuration, and charged through the source. Then, the capacitors are reconnected in a different configuration by turning the switches off/on, and generate high output voltage. This modular converter is able to produce flexible, high output voltage from low input voltage sources. The proposed converter is accordingly studied and analysed. To verify the operation of the given converter, it is simulated via the MATLAB‐based Simulink software, and an experimental prototype is subsequently implemented on a laboratory scale.