Pushing the Boundary of the 48 V Data Center Power Conversion in the AI and IoT Era

openThe increasing interest in cloud-based services, the Internet-of-Things and the take-over of artificial intelligence computing require constant improvement of the power distribution network. Electricity consumption of data centers, which drains a consistent slice of modern world energy production, is projected to increase tremendously during the next decade. Data centers are the backbone of modern economy; as a consequence, energy-aware resource allocation heuristics are constantly researched, leading the major IT services providers to develop new power conversion architectures to increase the overall webfarm distribution efficiency, together reducing the resulting carbon footprint and maximizing their investments. As higher voltage distribution yields lower conduction losses, vendors are moving from the 12 V rack bus to 48 V solutions together with research centers and especially data center developers. As mentioned, efficiency is crucial to address in this scenario and the whole conversion chain, i.e. from the 48 V bus to the CPU/GPU/ASIC voltage, must be optimized to decrease wasted energy inside the server rack. Power density for this converters family is also paramount to consider, as the overall system must occupy as less area and volume as possible. LLC resonant converters are commonly used as IBCs (intermediate bus converters), together with their GaN implementations because of their multiple advantages in efficiency and size, while multiphase-buck-derived topologies are the most common solution to step-down-to and regulate the final processor voltage as they're well-know, easy to scale and design. This dissertation proposes a family of non-isolated, innovative converters capable of increasing the power density and the efficiency of the state-of-the-art 48 V to 1.8/0.9 V conversion. In this work three solutions are proposed, which can be combined or used as stand-alone converters: an ASIC on-chip switched-capacitor resonant voltage divider, two unregulated Google-STC-derived topologies for the IBC stage (48 V to 12 V and 48 V to 4.8 V + 10.6 V dual-output) and a complete 48 V to 1.8 V ultra-dense PoL converter. Each block has been thoroughly tested and researched, therefore mathematical and experimental results are provided for each solution, together with state-of-the-art comparisons and contextualization.The increasing interest in cloud-based services, the Internet-of-Things and the take-over of artificial intelligence computing require constant improvement of the power distribution network. Electricity consumption of data centers, which drains a consistent slice of modern world energy production, is projected to increase tremendously during the next decade. Data centers are the backbone of modern economy; as a consequence, energy-aware resource allocation heuristics are constantly researched, leading the major IT services providers to develop new power conversion architectures to increase the overall webfarm distribution efficiency, together reducing the resulting carbon footprint and maximizing their investments. As higher voltage distribution yields lower conduction losses, vendors are moving from the 12 V rack bus to 48 V solutions together with research centers and especially data center developers. As mentioned, efficiency is crucial to address in this scenario and the whole conversion chain, i.e. from the 48 V bus to the CPU/GPU/ASIC voltage, must be optimized to decrease wasted energy inside the server rack. Power density for this converters family is also paramount to consider, as the overall system must occupy as less area and volume as possible. LLC resonant converters are commonly used as IBCs (intermediate bus converters), together with their GaN implementations because of their multiple advantages in efficiency and size, while multiphase-buck-derived topologies are the most common solution to step-down-to and regulate the final processor voltage as they're well-know, easy to scale and design. This dissertation proposes a family of non-isolated, innovative converters capable of increasing the power density and the efficiency of the state-of-the-art 48 V to 1.8/0.9 V conversion. In this work three solutions are proposed, which can be combined or used as stand-alone converters: an ASIC on-chip switched-capacitor resonant voltage divider, two unregulated Google-STC-derived topologies for the IBC stage (48 V to 12 V and 48 V to 4.8 V + 10.6 V dual-output) and a complete 48 V to 1.8 V ultra-dense PoL converter. Each block has been thoroughly tested and researched, therefore mathematical and experimental results are provided for each solution, together with state-of-the-art comparisons and contextualization.Dottorato di ricerca in Ingegneria industriale e dell'informazioneopenUrsino, Mari

A review on power electronics technologies for electric mobility

Concerns about greenhouse gas emissions are a key topic addressed by modern societies worldwide. As a contribution to mitigate such effects caused by the transportation sector, the full adoption of electric mobility is increasingly being seen as the main alternative to conventional internal combustion engine (ICE) vehicles, which is supported by positive industry indicators, despite some identified hurdles. For such objective, power electronics technologies play an essential role and can be contextualized in different purposes to support the full adoption of electric mobility, including on-board and off-board battery charging systems, inductive wireless charging systems, unified traction and charging systems, new topologies with innovative operation modes for supporting the electrical power grid, and innovative solutions for electrified railways. Embracing all of these aspects, this paper presents a review on power electronics technologies for electric mobility where some of the main technologies and power electronics topologies are presented and explained. In order to address a broad scope of technologies, this paper covers road vehicles, lightweight vehicles and railway vehicles, among other electric vehicles.This work has been supported by FCT – Fundação para a Ciência e Tecnologia with-in the Project Scope: UID/CEC/00319/2020. This work has been supported by the FCT Project DAIPESEV PTDC/EEI-EEE/30382/2017, and by the FCT Project new ERA4GRIDs PTDC/EEI-EEE/30283/2017. Tiago Sousa is supported by the doctoral scholarship SFRH/BD/134353/2017 granted by FCT

Development of a boost-inverter converter under electromagnetic compatibility stress equipping a photovoltaic generator

Introduction. Static converters are among the most widely used equipment in several applications, for example, electric power transmission, motor speed variation, photovoltaic panels, which constitute the electronic components. The design of a power electronics device is done without any real means of predicting electromagnetic disturbances during the product development phase. This case-by-case development process is repeated until a solution is found that best respects all the electromagnetic compatibility constraints. The purpose is the development of a boost-inverter converter under electromagnetic compatibility constraints. The improvements made to the inverter are mainly in the control, the choice of power switches and the electromagnetic compatibility solutions brought to the device. The quality of the wave is improved by acting on the type of control and the choice of switches. Methods. In the first time, we have highlighted a comparison between two most frequently used power components (MOSFET and IGBT) in the inverter and the boost by simulation using ISIS and LT-spice softwares. The sinusoidal voltage with modulation circuit is greatly simplified by the use of the PIC16F876A microcontroller. In a second step, we validate the obtained results with experimental measurements. We start with the boost, then the inverter. In addition, the circuits made are housed in boxes to avoid accidental contact for people. The equipment is designed to isolate the load from the power supply in case of: over voltages, under voltages, high and low battery level and short circuits. Results. All the simulations were performed using the ISIS and LT-spice softwares. The obtained results are validated by experimental measurements performed in the ICEPS Laboratory at the University of Sidi Bel-Abbes in Algeria. The realization of a single-phase inverter with a pulse width modulation control, associated with a boost chopper and the waveforms of the current and voltage across each static converter its opening are presented. The sources of disturbances in power devices are at the origin of the temporal and frequency characteristics of the signals coming from the hot spots of the power switches and the resonances created during the switching of these elements.Вступ. Статичні перетворювачі відносяться до обладнання, що найбільш широко використовується в декількох застосуваннях, наприклад, для передачі електроенергії, зміни швидкості двигуна, у фотогальванічних панелях, які складають електронні компоненти. Проєкт устрою силової електроніки виконується без будь-яких реальних засобів прогнозування електромагнітних перешкод на етапі розробки продукту. Цей процес індивідуальної розробки повторюється доти, доки знайдено рішення, яке найкраще враховує всі обмеження електромагнітної сумісності. Метою є розробка підвищувально-інверторного перетворювача при обмеженнях за електромагнітною сумісністю. Удосконалення, внесені в інвертор, в основному стосуються управління, вибору силових вимикачів та рішень щодо електромагнітної сумісності, реалізованих у пристрої. Якість хвилі покращується за рахунок впливу на тип керування та вибір перемикачів. Методи. Вперше ми підкреслили порівняння між двома найбільш часто використовуваними силовими компонентами (MOSFET та IGBT) в інверторі та підвищенням шляхом моделювання з використанням програмного забезпечення ISIS та LT-spice. Синусоїдальна напруга зі схемою модуляції значно спрощується за рахунок використання мікроконтролера PIC16F876A. На другому етапі ми підтверджуємо отримані результати експериментальними вимірами. Починаємо з Boost, потім з інвертора. Крім того, виготовлені схеми розміщені в коробках, щоб уникнути випадкового дотику людей. Устаткування призначене для відключення навантаження від джерела живлення у разі: перенапруги, зниженої напруги, високого та низького рівня заряду батареї та короткого замикання. Результати. Усі розрахунки проводилися з використанням програм ISIS та LT-spice. Отримані результати підтверджені експериментальними вимірами, проведеними в лабораторії ICEPS Університету Сіді-Бель-Аббес в Алжирі. Представлено реалізацію однофазного інвертора з керуванням на базі широтно-імпульсної модуляції, пов'язаного з підвищуючим переривником, а також осцилограми струму та напруги на кожному відкритті його статичного перетворювача. Джерелами збурень у силових пристроях є часові та частотні характеристики сигналів, що надходять від гарячих точок силових ключів, та резонанси, що створюються при комутації цих елементів

Design Space Evaluation for Resonant and Hard-charged Switched Capacitor Converters

USB Power Delivery enables a fixed ratio converter to operate over a wider range of output voltages by varying the input voltage. Of the DC/DC step-down converters powered from this type of USB, the hard-charged Switched Capacitor circuit is of interest to industry for its potential high power density. However implementation can be limited by circuit efficiency. In fully resonant mode, the efficiency can be improved while also enabling current regulation. This expands the possible applications into battery chargers and eliminates the need for a two-stage converter.In this work, the trade-off in power loss and area between the hard-charged and fully resonant switched capacitor circuit is explored using a technique that remains agnostic to inductor technology. The loss model for each converter is presented as well as discussion on the restrained design space due to parasitics in the passive components. The results are validated experimentally using GaN-based prototype converters and the respective design spaces are analyzed

A Novel Electric Insulation String Structure With High-Voltage Insulation and Wireless Power Transfer Capabilities

High-voltage insulation (HVI) strings are commonly used to hold high-voltage electric cables and electrically isolate them from the grounded transmission tower. In this paper, a novel concept of an electric insulation string with HVI and wireless power transfer (WPT) capabilities is presented. Based on the concept of the domino-resonator WPT system, this new structure consists of coil resonators embedded inside totally sealed insulation discs, which are then connected in series to form the new insulation string structure with the simultaneous HVI and WPT functions. This structure allows energy harvested from the ac magnetic field around the high-voltage cable to be transmitted wirelessly to power an online monitoring system in high-voltage transmission tower continuously, thereby reducing the storage requirements of the battery. The design and analysis of this new WPT structure based on the dimensions of commercially available HVI rod are included. Practical measurements obtained from a hardware prototype of about 25 W have been obtained to confirm the WPT capability of the proposal. An energy efficiency of more than 60% has been achieved for a transmission distance of 1.1 m over a wide range of load

Reducing switching losses of resonant inverter

This thesis report is submitted in partial fulfillment of the requirements for the degree of Bachelor of Science in Electrical and Electronic Engineering, 2015.Inverter is used in different purposes of lives. Inverters are required in a variety of applications including electronic ballasts for gas discharge lamps, induction heating and electrosurgical generators. These applications usually require a sinusoid of tens or hundreds of kHz having moderate or low harmonic distortion. Induction heater is another field where inverter is needed. It is one of the popular techniques of producing high temperature. Since the inverter has been invented long ago now different types of topologies came to light. Resonant inverter is one of them. Voltage and current source inverter was invented before resonant inverter, but resonant inverter has brought something new in engineering society. Now here is a point why resonant inverter is more important than voltage and current source inverter especially for those applications where output power control is needed. A very common term in electrical field is switching loss. In normal inverter circuits when the switches swap their positions they consume some powers, as they conduct their activities when both current and voltage are nonzero. As a result of imperfect switching causes power loss which is strongly unexpected. Moreover with the increase of switching frequencies power loss increases. As expected smaller size filter components needed higher frequencies. So the invented solution for avoiding the power loss is using a new type of inverter which is known as resonant inverter. The most significant part of resonant inverter is, here switching takes place when voltage and current are zero which is known as ‗soft switching‘. Since switching takes place in zero voltage and current stage there is no possibility of power loss in resonant inverter

High Frequency Power Converter with ZVT for Variable DC-link in Electric Vehicles

abstract: The most important metrics considered for electric vehicles are power density, efficiency, and reliability of the powertrain modules. The powertrain comprises of an Electric Machine (EM), power electronic converters, an Energy Management System (EMS), and an Energy Storage System (ESS). The power electronic converters are used to couple the motor with the battery stack. Including a DC/DC converter in the powertrain module is favored as it adds an additional degree of freedom to achieve flexibility in optimizing the battery module and inverter independently. However, it is essential that the converter is rated for high peak power and can maintain high efficiency while operating over a wide range of load conditions to not compromise on system efficiency. Additionally, the converter must strictly adhere to all automotive standards. Currently, several hard-switching topologies have been employed such as conventional boost DC/DC, interleaved step-up DC/DC, and full-bridge DC/DC converter. These converters face respective limitations in achieving high step-up conversion ratio, size and weight issues, or high component count. In this work, a bi-directional synchronous boost DC/DC converter with easy interleaving capability is proposed with a novel ZVT mechanism. This converter steps up the EV battery voltage of 200V-300V to a wide range of variable output voltages ranging from 310V-800V. High power density and efficiency are achieved through high switching frequency of 250kHz for each phase with effective frequency doubling through interleaving. Also, use of wide bandgap high voltage SiC switches allows high efficiency operation even at high temperatures. Comprehensive analysis, design details and extensive simulation results are presented. Incorporating ZVT branch with adaptive time delay results in converter efficiency close to 98%. Experimental results from a 2.5kW hardware prototype validate the performance of the proposed approach. A peak efficiency of 98.17% has been observed in hardware in the boost or motoring mode.Dissertation/ThesisMasters Thesis Electrical Engineering 201