Step-down DC-DC Converter Research Articles

A wide-output buck DC-DC power management IC

-This article designs and develops a wide-input voltage, high-efficiency, small-size, and peak current-mode control step-down DC-DC converter. The Cadence Spectre simulation tool is used for system simulation to verify the performance of the chip. The overall research content of the article includes the function of the output under heavy load, light load and the stability of the output under transient load changes. The specific content of the research is buck synchronous step-down DC-DC converter chip with pulse modulated. It is provided with an input-voltage range of 6 V–80 V and maximum output-voltage range 72 V. The chip possesses wide operating temperature range of −20 °C to 130 °C. The 92 % high-efficiency can be achieved by using a PWM/PFM hybrid modulation method. When achieving transient load jump, the output voltage change shall not exceed 150 mV. The maximum load current of the chip is 1 A. Furthermore, the chip is packaged and samples can be obtained, and the output light load/heavy load, and other functions are tested through the circuit board. In addition, the chip achieved tape out by using 0.18 μm CMOS process with size of 2027 μm × 2020 μm. The converter features current mode control to simplify external compensation and optimize transient response through a wide range of inductors and output capacitors. It can be adopted user-programmable soft-start time to prevent inrush current during startup. It also includes thermal shutdown protection to provide safe and smooth operation in operating conditions.

Resonant step-down DC-DC converter based on GaN power integrated circuits and SiC diodes

In the paper results of the operation and efficiency of a DC-DC resonant converter with a switched capacitor topology, equipped with GaN transistors and SiC diodes are presented. Investigated problems are related to the optimization of the DC- DC power electronic converter in order to achieve miniaturization, a simplified design and high efficiency. The proposed system operates at a high frequency with low switching losses. The proposed design helps to achieve uniform heating of the transistors and diodes, as demonstrated by the results of the thermal imaging measurements. The GaN transistors are integrated in one package with dedicated gate drivers and used to simplify the drivers circuitry and increase the power density factor of the proposed device. In the high-frequency design presented in the paper, the converter is implemented without electrolytic capacitors. The results included in the paper contain waveforms recorded in the power circuit at ZVS operation when switching on the transistors. It occurs when the system operates above the frequency of current oscillations in the resonant circuit of the switched capacitor. Efficiency characteristics and a voltage gain curve of the converter versus its output power are presented as well. Results of efficiency and quality of waveforms are important because they allow to characterize the tested system for the implementation using WBG devices. The use of integrated GaN modules to minimize elements in the physical system is also unique to this model and it allows for very short dead-time use, operation in ZVS mode at low reverse-conduction losses.

Design Considerations of Multi-Phase Buck DC-DC Converter

The main objective of this article is to propose a rational methodology for designing multi-phase step-down DC-DC converters, which can find applications both in engineering practice and in power electronics education. This study discusses the main types of losses in the multi-phase synchronous buck converter circuit (transistors’ conduction losses, high-side MOSFET’s switching losses, reverse recovery losses in the body diode, dead time losses, output capacitance losses in the MOSFETs, gate charge losses in MOSFETs, conduction losses in the inductor, and losses in the input and output capacitors) and provides analytical dependencies for their calculation. Based on the control examples for applications characterized by low voltage and high output current, the multi-phase buck converter’s output and input current ripples are analyzed and compared analytically and graphically (3D plots). Furthermore, graphical results of the converter efficiency at different numbers of phases (N = 2, 4, 6, 8, and 12) are presented. An analysis of the impact of various parameters on power losses is conducted. Thus, a discussion on assessing the factors influencing the selection of the number of phases in the multi-phase synchronous buck converter is presented. The proposed systematized approach, which offers a fast and accurate method for calculating power losses and overall converter efficiency, reduces the need for extensive preliminary computational procedures and achieves optimized solutions. Simulation results for investigating power losses in 8-phase multi-phase synchronous buck converters are also presented. The relative error between analytical and simulation results does not exceed 4%.

Conducted EMI Simulation for a DC-DC Converter: a DC Brush Motor System Considering Showering Arc at Mechanical Contacts

This paper provides an overview of a circuit analysis model for a DC brush motor, taking into consideration showering arc events. A mechanical contacts model that reproduces showering arc behavior is developed by combining new variable resistors with the steady arc model. As a result, spike surge waveforms can now be simulated via circuit analysis. It is also become clear that spike surges with continuous showering arcs constitute the maximum condition of conducted EMI. The measured and simulated conducted EMI show good agreement within 9 dB up to 108 MHz, in accordance with the CISPR 25 standard. Moreover, it is now possible to quantitatively predict the amount of conducted EMI in a system comprising a step-down DC-DC converter and a DC brush motor, by considering a dominant magnetic coupling and parasitic impedances.

Comparison of Control Method System by Using Perturbation and Observation Algorithms and Fuzzy Logic for the Maximum Power Point Control in Photovoltaic Systems

Currently, photovoltaic energy conversion has developed tremendously in the global energy industry. The enormous capacity of solar power plants generates electricity all over the world. Hundreds of gigawatts of electrical energy are supplied to the networks of various countries around the globe. In addition, up to hundreds of gigawatts of installed capacity of solar power plants are commissioned every year in all countries of the world. And this has been the trend for the past few decades. The main problem of solar photovoltaic conversion is the instability of the solar radiation flux associated with the climatic conditions in the regions where photovoltaic plants are operated. This problem can be solved by using highly efficient methods to control the generation of solar power plants, in particular, such as the use of information control systems for a particular PV system to increase the final generation of electrical energy supplied to the consumer. The photovoltaic (PV) conversion of solar radiation flux is an important renewable energy source. Due to the varying intensity of the sun, the electricity generated by PV directly from the radiation flux is not constant. The photovoltaic system currently uses maximum power point (PMP) tracking in perturbation and observation (P&O) mode to increase the final output power of the photovoltaic panels. A step-down DC-DC converter allows PMP to change the PV operating voltage and determine the maximum power output of the PV panel. This study proposes a fuzzy logic implementation. The magnitude of the perturbed voltage is determined by the change in power dq and the change in power relative to the change in voltage dq/dv is fuzzy. The performance of fuzzy logic is investigated in this work in order to optimize MPM. Fuzzy logic can simplify maximum power tracking and reduce voltage instability. According to the simulation results, the MPM method based on fuzzy computation performs better than the traditional P&O method. By using the proposed methods, we can significantly improve electric power generation and increase the efficiency of photovoltaic conversion.

A Dual-Mode Step-Down Converter with Automatic Mode Switch Circuit for System-on-Chip Applications

In this paper, a dual-mode step-down DC-DC converter with an automatic mode-switching circuit is implemented in a 28 nm digital CMOS process and embedded in an RF transceiver chip to power the digital part. The proposed automatic mode-switching circuit includes a frequency-voltage conversion circuit that is designed according to the principle of charge redistribution on capacitance. The converter can switch modes according to the load without external intervention. This converter, along with a PMU sequencer, can also provide a solution for low-power design for system-on-chip applications. The IC occupies a total die area of 0.378 mm2. The input voltage of the converter is 3.3 V, the output voltage is 1.05 V, and the maximum load current can reach 1 A. The converter shows a conversion efficiency of not less than 81% at a full load range and can achieve a peak conversion efficiency of 91% when the load current is 100 mA. The load range of the PWM mode is 1 A to 50 mA, and that of the PFM mode is 100 mA to 1 mA. The combination of zero-crossing detection circuitry and freewheel switches can reduce energy loss and eliminate additional electromagnetic interference.

A Coupled Inductor-Based Bidirectional DC-DC Converter with Step-Up Step-Down Operation for Electric Vehicle Applications

A coupled-inductor-based high step-up high step-down DC-DC converter with bidirectional capability suitable for electric vehicle (EV) applications is proposed in this paper. The voltage gain in both step-up and step-down operations is increased by a two-winding coupled inductor. The current ripple in the low-voltage port is low making it suitable for renewable energy sources. In addition, the low number of components causes the efficiency of the proposed converter to be competitive with similar topologies in the literature. Due to the use of only three bidirectional switches with low voltage stress, the cost and volume of the converter are reduced. To demonstrate the performance of the proposed bidirectional converter, an analysis of the operation modes in the steady state is presented. Also, a comparison between the suggested converter and other similar converters in the literature is provided. The results of these comparisons show that the proposed converter has a lower number of components and higher efficiency than the others. In addition, lower voltage stress and noticeable voltage gain in comparison with others are further results of these comparisons. Eventually, the experimental results in step-up and step-down operations are presented. In step-up operation, the experimental prototype is tested under fs = 50 kHz, VLow = 20 V, VHigh = 110 V, rated power = 120 W, with 94.60% efficiency. Furthermore, VHigh is considered 100 V with VLow = 33 V and 94.43% efficiency at 50 W rated power in step-down mode operation.

Development of Automatic Fish Feeding Machine for Integrated Floating Cage Aquageoponic System

Aims: The objective of this work was to develop and evaluate the performance of an automatic fish feeder- to enhance aquacultural practices and farmponds
 Place and Duration of Study: The research study was conducted at Madakasira, (Latitude: 13°56ʹ55.96″ N and Longitude: 77°18ʹ45.38″ E) which is located in Anantapur district of Andhra Pradesh, India. The mean annual temperature and annual rainfall of the study area are 27.6°C and 532 mm, respectively. Most of the rainfall (~80%) is received during South-West monsoon. The experiment study was conducted from March‒June, 2018.
 Methodology: Automatic fish feeder includes both electrical and mechanical mechanism. The materials includes for the development of the feeder was cone shape hopper, top covering lid, base, 12V DC motor, 12V 7Ah Rechargeable Lead Acid Battery, Arduino Uno, Bluetooth HC-05 module, 5v Relay, DC-DC step-down converter. The developed feeder was operated with the help of mobile app by using Bluetooth HC-05 module. The spreading distance and amount of feed spread, opening angles of the feeder were evaluated during the research period.
 Results: Our results showed that the amount of feed spread was maximum (140 g m-1) with 1.0 m height and was minimum (101 g m-1) at 0.2 m height. This results clearly shows that the fish feeder has to be kept at maximum height so that it covers maximum spreading distance with minimum loss of fish feed by drift. With increase in height of the machine from ground surface, the spreading distance of the fish feed from the feeding machine was also increased.
 Conclusion: Farmers were satisfied with this new technology which helps to avoid manual feeding and provides the clean environment.

A V2G Enabled Bidirectional Single/Three-Phase EV Charging Interface Using Modular Multilevel Buck PFC Rectifier

The battery charging power electronics interface of an electric vehicle (EV) must be capable of bidirectional power flow to enable both grid-to-vehicle (G2V) and vehicle-to-grid (V2G) operations. In the presence of a single/three-phase AC supply, the front-end of the EV charger employs a power factor correction (PFC) rectifier, which should have the bidirectional capability to facilitate V2G mode. A conventional active rectifier functions in boost mode while performing PFC and voltage regulation. In most of the currently available EVs, however, the battery nominal voltage is low and, hence, a downstream high step-down DC-DC converter and high voltage DC bus capacitor are required in the charging interface. To overcome these issues, this work proposes a bidirectional AC-to-DC buck rectifier topology that can operate in G2V and V2G modes, both in single- and three-phase versions. The proposed topology utilizes the switched capacitors principle to achieve self-balancing of voltages in the capacitors. In addition, it is highly modular in structure. This paper describes the proposed topology, its working and modulation and its applications. The hardware proto model is used to validate the proposed power converter and the control approach to achieve PFC and voltage regulation. In addition, a comparison with other topologies is presented to demonstrate its competence.

Maximum Power Point Tracking of an Off-Grid Photovoltaic System Consisting of a Series Connected Supercapacitor with a Step-Down Converter

An off-grid photovoltaic (PV) system's PV array is connected with a charge controller as the first power conversion stage. The average efficiency of the power stage of charge controllers is around 90%. Supercapacitor (SC) battery hybrid PV system is a novel PV system that utilizes some of the wasted energy of a typical system and enhances the system's efficiency up to 98%. However, the feasibility of maximum power point tracking (MPPT) for this system is yet to be validated. This paper presents a comparative study to adapt MPPT for the proposed system consisting of a series-connected SC bank with PV array and step-down DC-DC converter. The step-down converter is used as the impedance matching network. Different solar irradiance profiles were emulated to check the feasibility and efficiency of MPPT. Experimentally, it was shown that the typical MPPT could be adapted to the proposed PV system with very high MPPT efficiency.

Design and Simulation of Synchronous Buck Converter in Comparison with Regular Buck Converter

In a variety of low-power applications, a step-down dc-dc converter is used to reduce the voltage from a higher level. The two types of dc-dc converters are a regular buck and synchronous buck. The synchronous buck utilizes two switches and one diode, whereas the regular buck uses one switch and one diode. Many converters rely on the power components' switching qualities to work. A second MOSFET is required due to the diode's higher conduction losses. Because of the diode's conduction losses, the converter's efficiency may be reduced. The use of a synchronous buck converter improves efficiency by reducing diode losses. The main goal of this study is to compare and contrast these two low-power step-down converters. The simulation in this work was performed using the LTSPICE program.

Some Remarks on the Design of Robust PIR Controllers for Step-Down DC-DC Converters

In this paper, we consider the problem of regulating the output voltage of a Direct-Current-to-Direct-Current (DC-DC) buck converter when the input source is partially known, and the parameters of the converter are uncertain. Our objectives are: (i) to render the system with improved speed of response in spite of high-frequency measurement noise and, (ii) to guarantee robustness against uncertainties and disturbance attenuation in the face of unknown input signals. To fulfill objective (i), we utilize a Proportional-Integral-Retarded (PIR) controller to mitigate high-frequency measurement noise without compromising the system's bandwidth. This is accomplished by placing the rightmost poles of the closed-loop system at an appropriate locus in the complex plane. To fulfill objective (ii), we first keep the controller design in (i) and then, we derive sufficient stability conditions via a rigorous L2-gain analysis. To our knowledge, these results are novel and further equip PIR controllers with much-needed, but previously missing, robust and H∞ properties. Numerical examples testify to the feasibility of the proposed approach on a low-power DC-DC buck converter.

48-V Input DC-DC High Step-Down Converter in GaN-Based Design

This paper presents a novel high step-down DC-DC converter based on a switched-capacitor resonant topology. It is presented in a 48/8 V version, which was verified by simulations and experiments. The most notable features specific to this converter are an almost non-iductive design and relatively low voltage stress across switching devices. The proposed topology allows for zero-current-switching (ZCS) and zero-voltage-switching (ZVS). Experimental tests confirm that ZVS operation brings a significant increase in the efficiency of the proposed device. Taking into account all the advantages of the suggested converter, it can be concluded that this device is suitable for any application where a high step-down voltage conversion is required. In a prospective application, the proposed converter can be utilized as a part of the power supply unit for data centers.

Стабилизация напряжения шины постоянного тока автономного инвертора в составе частотноуправляемого электропривода с накопителем энергии на суперконденсаторах

Рассмотрена проблема поддержания напряжения на шине постоянного тока преобразователя частоты с автономным инвертором, входящим в состав электропривода переменного тока с частотным способом регулирования скорости. Электропривод снабжен накопителем энергии на суперконденсаторах, сопряженных с шиной постоянного тока через реверсивный повышающе-понижающий преобразователь постоянного тока в постоянный ток. При решении проблемы использована концепция поддержания напряжения шины постоянного тока на заданном уровне путем компенсации тока нагрузки автономного инвертора внешним током накопителя энергии. Накопитель энергии снабжен одноконтурной следящей системой регулирования тока. Представлены несколько вариантов систем регулирования тока, построенных по принципу комбинированного управления. Цель работы - оценка точности стабилизации напряжения на шине постоянного тока автономного инвертора. Выполнен теоретический анализ коэффициентов ошибок систем регулирования тока. Проведено моделирование электропривода без учета и с учетом дискретности преобразователя накопителя энергии. Результаты исследования могут быть полезны при разработке систем регулирования накопителей энергии на суперконденсаторах для различных приложений.

Step-Down DC-DC Converter for Solid-State Marx Generator

A compact step-down dc-dc converter has been developed for applications to solid-state Marx generator. The purpose is to allow Marx switches to be able to operate without direct power supply from the ground level circuits. The main voltage across the switch is used as the power source which is converted to a dc voltage that can be used to power the drivers of the solid-state switches. Experiments have been carried out to demonstrate the ability and the performance of the dc-dc converter, as well as its effectiveness in a four-stage Marx generator.

Design of Transformerless Single Stage Double Switch Step Down PLL Derived Inverter using Single Phase Grid Connected PV Module with MPP Tracking

Here we propose a single stage double switch (SSDS) converter for single phase grid connected photo voltaic inverter step-down module, the structure is designed and modelled to a highly reliable step-down buck DC-DC converter and robust from the input derived from the PV module. The proposed PV module uses perturb and observe algorithm reference voltage to gain the maximum power in different changing climatic conditions. The grid is designed for 110 V/50 Hz, since it’s a low frequency, the utilization of heavy and expensive transformer is avoided, In a grid connected systems usually transformer is employed in the power conversion stage to provide sudden isolation between the PV system and the grid, and also ensures that no continuous current is injected into the grid by avoiding leakage currents between the PV module and the ground. As a choice to the grid connected module with line transformer, a transformer less inverter topology is discussed, to avoid the leakage currents possibly occurring due to the capacitance between the PV array and ground, an inverter topology with PLL is proposed to avoid common mode voltage and the increase in electromagnetic emissions. This paper provides a highly efficient transformer less photovoltaic grid topology with reduced switches and has been validated by simulation.

Design and Implementation of Improved High Step-Down DC-DC Converter for Electric Vehicles

An improved high step-down DC-DC converter for charging the batteries in an electric vehicle application is proposed in this paper. It adopts the topology of the conventional full-bridge converter, which has a coupled inductor current-doubler rectifier as the secondary side of the transformer. In addition, four power switches are driven using a phase-shifting technique. The proposed converter can achieve a high step-down voltage with low-voltage stress on the rectifier diodes. In addition, the coupled inductor current-doubler rectifier of the secondary side can reduce the ripple current and losses of the secondary side to achieve high efficiency. Furthermore, the proposed converter can overcome the drawbacks of the conventional full-bridge converter, such as switching loss caused by high switching frequency, duty-cycle loss, voltage stress, and numerous components, and can increase the efficiency with the soft-switching technique. A 600 W laboratory prototype of the proposed converter was manufactured. The results of the experiments performed with the prototype proved the effectiveness and validated the use of the proposed converter for better charging of electric vehicles.

A new soft‐switching high step‐down DC‐DC converter for voltage regular module application

This study proposes a high step-down DC-DC converter with minimum elements. In the proposed converter, soft switching condition is provided with only one auxiliary switch, which simplifies the structure of the converter. Leakage inductor energy is used to create a zero voltage condition; so the mutations created by this inductor are neutralised. The control of the auxiliary switch is complementary to the main switch, which does not require a new and complex control circuit. Due to low voltage gain, the proposed converter is suitable for use in voltage regulator modules. The proposed converter is completely analysed. To confirm the theoretical analysis, an experimental sample is made and tested at 15 W and the results are presented. Also, the efficiency of the proposed converter at full load is 97.5%.

Implementation of Fuzzy Logic Controller for DC DC step Down Converter

This paper presents the design of a Fuzzy logic controller for a DC-DC step-down converter. Buck converters are step-down regulated converters which convert the DC voltage into a lower level standardized DC voltage. The buck converters are used in solar chargers, battery chargers, quadcopters, industrial and traction motor controllers in automobile industries etc. The major drawback in buck converter is that when input voltage and load change, the output voltage also changes which reduces the overall efficiency of the Buck converter. So here we are using a fuzzy logic controller which responds quickly for perturbations, compared to a linear controllers like P, PI, PID controllers. The Fuzzy logic controllers have become popular in designing control application like washing machine, transmission control, because of their simplicity, low cost and adaptability to complex systems without mathematical modeling So we are implementing a fuzzy logic controller for buck converter which maintains fixed output voltage even when there are fluctuations in supply voltage and load. The fuzzy logic controller for the DC-DC Buck converter is simulated using MATLAB SIMULINK. The proposed approach is implemented on DC-DC step down converter for an input of 230V and we get the desired output for variations in load or references. This proposed system increases the overall efficiency of the buck converter.

On optimization of manufacturing of a step-down DC-DC converter to increase integration density of elements

<p>We consider possibility to increase field-effect transistor's density in a switched-capacitor step-down DC-DC converter. Based on this approach we analyzed manufacturing of the converter in a heterostructure with special structure. Some specific sections of the heterostructure must be doped by ion implantation or by diffusion. After this procedure optimized annealing has been done. We also obtained conditions for decreasing of mismatch-induced stress value in this heterostructure. An analytical approach for analysis of heat and mass transport in multilayer structures has been introduced. The approach gives a possibility without crosslinking of solutionson interfaces between layers, take into account (i) spatial variation of parameters of considered processes; (ii) temporal variation of parameters of considered processes; (iii) nonlinearity of considered processes; (iv) mismatch-induced stress.</p>