Editorial

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2 pages, 154 KiB

Open AccessEditorial

Current Research on Embedded DC/DC Converters

by Anna Richelli

Energies 2021, 14(19), 6142; https://doi.org/10.3390/en14196142 - 27 Sep 2021

Cited by 1 | Viewed by 1283

Abstract

In several energy applications, DC/DC converters are one of the most important components [...] Full article

(This article belongs to the Special Issue Current Researches on Integrated DC/DC Converters)

Research

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14 pages, 8007 KiB

Open AccessFeature PaperArticle

A PWM/PFM Dual-Mode DC-DC Buck Converter with Load-Dependent Efficiency-Controllable Scheme for Multi-Purpose IoT Applications

by Myeong Woo Kim and Jae Joon Kim

Energies 2021, 14(4), 960; https://doi.org/10.3390/en14040960 - 11 Feb 2021

Cited by 7 | Viewed by 5591

Abstract

This paper presents a dual-mode DC-DC buck converter including a load-dependent, efficiency-controllable scheme to support multi-purpose IoT applications. For light-load applications, a selectable adaptive on-time pulse frequency modulation (PFM) control is proposed to achieve optimum power efficiency by selecting the optimum switching frequency [...] Read more.

This paper presents a dual-mode DC-DC buck converter including a load-dependent, efficiency-controllable scheme to support multi-purpose IoT applications. For light-load applications, a selectable adaptive on-time pulse frequency modulation (PFM) control is proposed to achieve optimum power efficiency by selecting the optimum switching frequency according to the load current, thereby reducing unnecessary switching losses. When the inductor peak current value or converter output voltage ripple are considered in some applications, its on-time can be adjusted further. In heavy-load applications, a conventional pulse width modulation (PWM) control scheme is adopted, and its gate driver is structured to reduce dynamic current, preventing the current from shooting through the power switch. A proposed dual-mode buck converter prototype is fabricated in a 180 nm CMOS process, achieving its measured maximum efficiency of 95.7% and power density of 0.83 W/mm². Full article

(This article belongs to the Special Issue Current Researches on Integrated DC/DC Converters)

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17 pages, 10626 KiB

Open AccessArticle

A Family of High Voltage Gain Three-Level Step-Up Converters for Photovoltaic Module Integration Applications

by Ahmad Alzahrani, Pourya Shamsi and Mehdi Ferdowsi

Energies 2020, 13(22), 6115; https://doi.org/10.3390/en13226115 - 22 Nov 2020

Cited by 2 | Viewed by 1911

Abstract

This paper proposes a family of step-up three-level DC-DC converter topologies suitable for photovoltaic panel integration applications. The proposed family is suitable to convert the 10–30 V from photovoltaic panels to a 150 V direct current distribution bus. The proposed family enhances the [...] Read more.

This paper proposes a family of step-up three-level DC-DC converter topologies suitable for photovoltaic panel integration applications. The proposed family is suitable to convert the 10–30 V from photovoltaic panels to a 150 V direct current distribution bus. The proposed family enhances the three-level topology in terms of the voltage gain, power density, and filtering requirements at the input level. The filtration is reduced by interleaving. The three-level boost converter’s voltage gain is enhanced by utilizing several options such as switched capacitor cells, switched inductor cells, and flyback transformers or coupled inductors. The enhancement techniques are illustrated by providing the circuit diagram and a comparison of the voltage gain and the number of required components. An example converter of a hybrid three-level boost converter with a flyback transformer is presented to convert 20 V from a photovoltaic panel to a 400 V. The theory of operation and steady-state analysis are provided for the example converter operating in the continuous conduction mode. The converter is simulated to extract the power from three PVL-136 photovoltaic (PV) panels by applying a maximum power point tracking algorithm. The theory of operation and simulation are confirmed with an 80 W experimental prototype, which has an efficiency of around

95 %

at 40 W load power. Full article

(This article belongs to the Special Issue Current Researches on Integrated DC/DC Converters)

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13 pages, 6552 KiB

Open AccessArticle

Design and Implementation of Solar OLED Lighting Driver Circuit with Frequency Modulation Control

by Zhong-Rong Lin and Huang-Jen Chiu

Energies 2020, 13(21), 5608; https://doi.org/10.3390/en13215608 - 27 Oct 2020

Cited by 3 | Viewed by 1722

Abstract

This paper proposes a single-stage single-ended primary inductor converter (SEPIC) converter circuit, which is applied to the organic light-emitting diodes (OLED) driver circuit. The circuit proposed in this paper replaces the output Schottky diode from the original SEPIC with a power switch. Deadtime [...] Read more.

This paper proposes a single-stage single-ended primary inductor converter (SEPIC) converter circuit, which is applied to the organic light-emitting diodes (OLED) driver circuit. The circuit proposed in this paper replaces the output Schottky diode from the original SEPIC with a power switch. Deadtime is added to prevent the on-state overlapping of two switches with zero voltage switching (ZVS), and the circuit operates in triangular current mode. The digital control methods are maximum power point tracking and frequency modulation using a battery to supply the converter and illuminate the OLED at night. Finally, a prototype is implemented to show the feasibility under the DC input voltage range of 10–40 V. The DC output is 12 V/1 A/12 W, and the conversion efficiency is up to 96.3%. Full article

(This article belongs to the Special Issue Current Researches on Integrated DC/DC Converters)

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11 pages, 3598 KiB

Open AccessArticle

A Bipolar ±13 mV Self-Starting and 85% Peak Efficiency DC/DC Converter for Thermoelectric Energy Harvesting

by Harald Dillersberger, Bernd Deutschmann and Douglas Tham

Energies 2020, 13(20), 5501; https://doi.org/10.3390/en13205501 - 20 Oct 2020

Cited by 10 | Viewed by 2814

Abstract

This paper presents a novel converter for boosting the low-voltage output of thermoelectric energy harvesters to power standard electronic circuits. The converter can start up from a fully depleted state of the system off a bipolar ±13 mV input and can boost it [...] Read more.

This paper presents a novel converter for boosting the low-voltage output of thermoelectric energy harvesters to power standard electronic circuits. The converter can start up from a fully depleted state of the system off a bipolar ±13 mV input and can boost it to output voltages of up to 5 V. The converter comprises two transformers, one for each polarity that are multiplexed between an oscillator (used during startup) and a flyback converter (used during normal operation). To eliminate leakage currents in the input stage, the unused converter is completely turned off at startup and both converters are automatically shut off if the input power is found to be too low. Measurement results of the converter designed in a 180 nm CMOS process demonstrate a peak end-to-end conversion efficiency of 85% and nearly perfect impedance matching over the full input voltage range. This is the first time that a converter for ultra-low bipolar input voltages achieves the same performance as a unipolar converter. Full article

(This article belongs to the Special Issue Current Researches on Integrated DC/DC Converters)

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21 pages, 6774 KiB

Open AccessArticle

Stability Analysis and Optimal Design for Virtual Impedance of 48 V Server Power System for Data Center Applications

by Chien-Chun Huang, Sheng-Li Yao and Huang-Jen Chiu

Energies 2020, 13(20), 5253; https://doi.org/10.3390/en13205253 - 10 Oct 2020

Cited by 1 | Viewed by 2161

Abstract

In the past literature on virtual impedance to series systems, most of the discussion focused on stability without in-depth research on the system design of the series converter and the overall output impedance. Accordingly, this study takes an open-loop resonant LLC converter series-connected [...] Read more.

In the past literature on virtual impedance to series systems, most of the discussion focused on stability without in-depth research on the system design of the series converter and the overall output impedance. Accordingly, this study takes an open-loop resonant LLC converter series-connected closed-loop Buck converter as an example. First, the conditions required for the direct connection of the small-signal model in the series, the effect of feedback compensation on the input impedance of the load stage, the operating frequency, and passive components of the two-stage converter are discussed in detail―the relationship between the matching and the output impedance. Afterwards, a mathematical model is used to discuss the effect of adding parallel virtual impedance on the output impedance of the overall series converter and then derive an optimized virtual impedance design. Finally, an experimental platform of 48 V to 12 V and maximum wattage of 96 W are implemented. The output impedance of the series converter is measured with an impedance analyzer to verify the theoretical analysis proposed in this paper. Full article

(This article belongs to the Special Issue Current Researches on Integrated DC/DC Converters)

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Review

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22 pages, 9111 KiB

Open AccessReview

A Review of Fully Integrated and Embedded Power Converters for IoT

by Anna Richelli, Mohamed Salem and Luigi Colalongo

Energies 2021, 14(17), 5419; https://doi.org/10.3390/en14175419 - 31 Aug 2021

Cited by 12 | Viewed by 2428

Abstract

The Internet of Things (IoT) has found application in many components of implantable medical devices, wearable smart devices, monitoring systems, etc. The IoT devices are conventionally battery powered, even though, in several low power applications, they can also be powered using energy harvesting [...] Read more.

The Internet of Things (IoT) has found application in many components of implantable medical devices, wearable smart devices, monitoring systems, etc. The IoT devices are conventionally battery powered, even though, in several low power applications, they can also be powered using energy harvesting technology. Independently of the power sources (if batteries or environment), efficient and robust power converters must be designed to provide the small and distributed energy required by such IoT devices. This review paper will first provide an overview about the power consumption in IoT devices; second, it will discuss the most recent research and advance in the field of fully-integrated or embedded DC/DC converters, starting from high-performance integrated charge pumps or embedded inductive boost converters for specific harvesting sources (temperature, solar, and so on), to novel DC/DC converters for multiple energy sources. Full article

(This article belongs to the Special Issue Current Researches on Integrated DC/DC Converters)

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28 pages, 3498 KiB

Open AccessReview

An Overview of Fully Integrated Switching Power Converters Based on Switched-Capacitor versus Inductive Approach and Their Advanced Control Aspects

by G Kiran Kumar, Tarakanath Kobaku, Subham Sahoo, Bidyadhar Subudhi, Devaraj Elangovan and Frede Blaabjerg

Energies 2021, 14(11), 3250; https://doi.org/10.3390/en14113250 - 02 Jun 2021

Cited by 6 | Viewed by 3724

Abstract

This paper reviews and discusses the state of the art of integrated switched-capacitor and integrated inductive power converters and provides a perspective on progress towards the realization of efficient and fully integrated DC–DC power conversion. A comparative assessment has been presented to review [...] Read more.

This paper reviews and discusses the state of the art of integrated switched-capacitor and integrated inductive power converters and provides a perspective on progress towards the realization of efficient and fully integrated DC–DC power conversion. A comparative assessment has been presented to review the salient features in the utilization of transistor technology between the switched-capacitor and switched inductor converter-based approaches. First, applications that drive the need for integrated switching power converters are introduced, and further implementation issues to be addressed also are discussed. Second, different control and modulation strategies applied to integrated switched-capacitor (voltage conversion ratio control, duty cycle control, switching frequency modulation, R_on modulation, and series low drop out) and inductive converters (pulse width modulation and pulse frequency modulation) are then discussed. Finally, a complete set of integrated power converters are related in terms of their conditions and operation metrics, thereby allowing a categorization to provide the suitability of converter technologies. Full article

(This article belongs to the Special Issue Current Researches on Integrated DC/DC Converters)

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23 pages, 2591 KiB

Open AccessEditor’s ChoiceReview

Review of Multilevel Inverters for PV Energy System Applications

by Ali Bughneda, Mohamed Salem, Anna Richelli, Dahaman Ishak and Salah Alatai

Energies 2021, 14(6), 1585; https://doi.org/10.3390/en14061585 - 12 Mar 2021

Cited by 110 | Viewed by 9184

Abstract

Over the last decade, energy demand from the power grid has increased significantly due to the increasing number of users and the emergence of high-power industries. This has led to a significant increase in global emissions with conventional energy generation. Therefore, the penetration [...] Read more.

Over the last decade, energy demand from the power grid has increased significantly due to the increasing number of users and the emergence of high-power industries. This has led to a significant increase in global emissions with conventional energy generation. Therefore, the penetration of renewable energy resources into the power grid has increased significantly. Photovoltaic systems have become the most popular resources as their protentional is enormous, thus, the worldwide installed PV capacity has increased to more than 635 gigawatts (GW), covering approximately 2% of the global electricity demand. Power electronics are an essential part of photovoltaic generation; the drive for efficient power electronic converters is gaining more and more momentum. Presently, multilevel inverters (MLI) have become more attractive to researchers compared to two-level inverters due to their abilities to provide lower electromagnetic interference, higher efficiency, and larger DC link voltages. This paper reviews multilevel inverters based on their classifications, development, and challenges with practical recommendations in utilizing them in renewable energy systems. Moreover, PV systems with various maximum power point tracking (MPPT) methods have been extensively considered in this paper as well. The importance and the development of a modified multilevel inverter are also highlighted in this review. In general, this paper focuses on utilizing multilevel inverters for PV systems to motivate and guide society to focus on inventing an efficient and economical multilevel inverter that has the combined capabilities of these converters reported in the literature. Full article

(This article belongs to the Special Issue Current Researches on Integrated DC/DC Converters)

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