A new Li-ion battery charger with charge mode selection based on 0.18 um CMOS for phone applications

A new architecture of Li-Ion battery charger with charge mode selection is presented in this work. To ensure high efficiency, good accuracy and complete protection mode, we propose an architecture based on variable current source, temperature detector and power control. To avoid the risk of damage, the Li- Ion batteries charging process must change between three modes of current (trickle current (TC), constant current (CC), and constant voltage (CV)) in order to charge the battery with degrading current. However, the interest of this study is to develop a fast battery charger with high accuracy that is able to switch between charging modes without reducing its power efficiency, and to guarantee a complete protection mode. The proposed charger circuit is designed to control the charging process in three modes using the charging mode selection. The obtained results show that the Li-ion batteries can be successfully charged in a short time without reducing their efficiency. The proposed charger is implemented in 180 nm CMOS technology with a maximum charging current equal to 1 A and a maximum battery voltage equal to 4.22 V, (with input range 2.7-4.5 V). The chip area is 1.5 mm2 and the power efficiency is 90.09 %

High Performance Power Management Integrated Circuits for Portable Devices

abstract: Portable devices often require multiple power management IC (PMIC) to power different sub-modules, Li-ion batteries are well suited for portable devices because of its small size, high energy density and long life cycle. Since Li-ion battery is the major power source for portable device, fast and high-efficiency battery charging solution has become a major requirement in portable device application. In the first part of dissertation, a high performance Li-ion switching battery charger is proposed. Cascaded two loop (CTL) control architecture is used for seamless CC-CV transition, time based technique is utilized to minimize controller area and power consumption. Time domain controller is implemented by using voltage controlled oscillator (VCO) and voltage controlled delay line (VCDL). Several efficiency improvement techniques such as segmented power-FET, quasi-zero voltage switching (QZVS) and switching frequency reduction are proposed. The proposed switching battery charger is able to provide maximum 2 A charging current and has an peak efficiency of 93.3%. By configure the charger as boost converter, the charger is able to provide maximum 1.5 A charging current while achieving 96.3% peak efficiency. The second part of dissertation presents a digital low dropout regulator (DLDO) for system on a chip (SoC) in portable devices application. The proposed DLDO achieve fast transient settling time, lower undershoot/overshoot and higher PSR performance compared to state of the art. By having a good PSR performance, the proposed DLDO is able to power mixed signal load. To achieve a fast load transient response, a load transient detector (LTD) enables boost mode operation of the digital PI controller. The boost mode operation achieves sub microsecond settling time, and reduces the settling time by 50% to 250 ns, undershoot/overshoot by 35% to 250 mV and 17% to 125 mV without compromising the system stability.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201

DEVELOPMENT OF A CURRENT CONTROL ULTRACAPACITOR CHARGER BASED ON DIGITAL SIGNAL PROCESSING

Ultracapacitor usually use as a short-term duration electrical energy storage because it has several advantages, like high power density (5kW/kg), long lifecycle and very good charge/discharge efficiency. Unlike batteries, ultracapacitors may be charged and discharged at similar rates. This is very useful in energy recovery systems such as dynamic braking of transport systems.  Here are a few characteristics of ultracapacitors that should be kept in mind when integrating/designing a charging system for the intended application. An ultracapacitor with zero charge looks like a short circuit to the charging source. Most of low cost power supplies fold back the output current in response to a perceived short circuit, making them unsuitable for charging of ultracapacitors. Ultracapacitors have a low series inductance allowing easy stabilizing with switch mode chargers. The RC time constant of passive charging networks is usually too long. Therefore, linear regulators are inefficient components for ultracapacitor charging. In this paper, the development of a current control ultracapacitor charger based on Digital Signal Processing (DSP) is presented.

Review of Electric Vehicle Charging Technologies, Configurations, and Architectures

Electric Vehicles (EVs) are projected to be one of the major contributors to energy transition in the global transportation due to their rapid expansion. The EVs will play a vital role in achieving a sustainable transportation system by reducing fossil fuel dependency and greenhouse gas (GHG) emissions. However, high level of EVs integration into the distribution grid has introduced many challenges for the power grid operation, safety, and network planning due to the increase in load demand, power quality impacts and power losses. An increasing fleet of electric mobility requires the advanced charging systems to enhance charging efficiency and utility grid support. Innovative EV charging technologies are obtaining much attention in recent research studies aimed at strengthening EV adoption while providing ancillary services. Therefore, analysis of the status of EV charging technologies is significant to accelerate EV adoption with advanced control strategies to discover a remedial solution for negative grid impacts, enhance desired charging efficiency and grid support. This paper presents a comprehensive review of the current deployment of EV charging systems, international standards, charging configurations, EV battery technologies, architecture of EV charging stations, and emerging technical challenges. The charging systems require a dedicated converter topology, a control strategy and international standards for charging and grid interconnection to ensure optimum operation and enhance grid support. An overview of different charging systems in terms of onboard and off-board chargers, AC-DC and DC-DC converter topologies, and AC and DC-based charging station architectures are evaluated

Development of a hybrid power management unit for mobile applications: solar energy case study

Applying photovoltaic power to mobile devices has become a hot area of research due to the availability of solar energy. Usage of photovoltaic as the power source for mobile devices will enhance device performance. There are many challenges to interface photovoltaic energy to mobile loads such as variation of power coming out from photovoltaic panels, unregulated voltage and limited power. Maximum power point tracking (MPPT) is used in photovoltaic systems to maximize the photovoltaic array output power under environmental variations such as irradiation and temperature for mobile applications. A power management system is proposed to apply photovoltaic harvested energy effectively to mobile or handheld devices while running workloads. The proposed system mainly consists of a MPPT block and a Power Distribution Control Unit (PDCU). The PDCU allows usage of an AC/DC external in case of insufficient photovoltaic power in order to maintain the load running. Different cases of operation are handled by the PDCU unit depending on the availability of photovoltaic power, load power, battery state of charge and existence of the AC/DC external. In addition, a new MPPT algorithm is proposed to provide fast and accurate tracking. Analysis and simulation results are provided to demonstrate system functionality and performance sensitivity. Moreover, a prototype of the proposed system is still under progress, to verify the possibility of building such system

Design of Power Management Integrated Circuits and High-Performance ADCs

A battery-powered system has widely expanded its applications to implantable medical devices (IMDs) and portable electronic devices. Since portable devices or IMDs operate in the energy-constrained environment, their low-power operations in combination with efficiently sourcing energy to them are key problems to extend device life. This research proposes novel circuit techniques for two essential functions of a power receiving unit (PRU) in the energy-constrained environment, which are power management and signal processing. The first part of this dissertation discusses power management integrated circuits for a PRU. From a power management perspective, the most critical two circuit blocks are a front-end rectifier and a battery charger. The front-end CMOS active rectifier converts transmitted AC power into DC power. High power conversion efficiency (PCE) is required to reduce power loss during the power transfer, and high voltage conversion ratio (VCR) is required for the rectifier to enable low-voltage operations. The proposed 13.56-MHz CMOS active rectifier presents low-power circuit techniques for comparators and controllers to reduce increasing power loss of an active diode with offset/delay calibration. It is implemented with 5-V devices of a 0.35 µm CMOS process to support high voltage. A peak PCE of 89.0%, a peak VCR of 90.1%, and a maximum output power of 126.7 mW are measured for 200Ω loading. The linear battery charger stores the converted DC power into a battery. Since even small power saving can be enough to run the low-power PRU, a battery charger with low IvQ is desirable. The presented battery charger is based on a single amplifier for regulation and the charging phase transition from the constant-current (CC) phase to the constant-voltage (CV) phase. The proposed unified amplifier is based on stacked differential pairs which share the bias current. Its current-steering property removes multiple amplifiers for regulation and the CC-CV transition, and achieves high unity-gain loop bandwidth for fast regulation. The charger with the maximum charging current of 25 mA is implemented in 0.35 µm CMOS. A peak charger efficiency of 94% and average charger efficiency of 88% are achieved with an 80-mAh Li-ion polymer battery. The second part of this dissertation focuses on analog-to-digital converters (ADCs). From a signal processing perspective, an ADC is one of the most important circuit blocks in the PRU. Hence, an energy-efficient ADC is essential in the energy-constrained environment. A pipelined successive approximation register (SAR) ADC has good energy efficiency in a design space of moderate-to-high speeds and resolutions. Process-Voltage-Temperature variations of a dynamic amplifier in the pipelined-SAR ADC is a key design issue. This research presents two dynamic amplifier architectures for temperature compensation. One is based on a voltage-to-time converter (VTC) and a time-to-voltage converter (TVC), and the other is based on a temperature-dependent common-mode detector. The former amplifier is adopted in a 13-bit 10-50 MS/s subranging pipelined-SAR ADC fabricated in 0.13-µm CMOS. The ADC can operate under the power supply voltage of 0.8-1.2 V. Figure-of-Merits (FoMs) of 4-11.3 fJ/conversion-step are achieved. The latter amplifier is also implemented in 0.13-µm CMOS, consuming 0.11 mW at 50 MS/s. Its measured gain variation is 2.1% across the temperature range of -20°C to 85 °C

Hybrid energy storage systems via power electronic converters

In recent years, many research lines have focused their efforts on improving energy efficiency and developing renewable energy sources. In this context, the use of energy storage systems is on the rise, as they can contribute to the integration of renewables to the main electrical grid. However, energy storage systems are divided into high energy or high power devices. Due to the lack of a solution covering both aspects, researchers are forced to find alternatives. The hybridization of different energy storage technologies is presented as a suitable solution for this problem, since it combines high power and high energy within the same system. The main goal of this thesis is the design and implementation of a hybrid energy storage system (HESS), capable of improving the performance provided by a single storage technology. As a first step in this direction, this document reviews and classifies the most relevant HESS topologies found in the literature. This allows a better understanding of the drawbacks and benefits of each configuration. To ensure the optimal use of this HESS, it is essential to design a suitable energy management strategy and a proper power electronic converter control. To this end, the control structure has been analyzed from different approaches. On the one hand there would be the classic multilevel control structure, which usually consists of three levels among which are the operating constraints, the power sharing and at the lowest level the control of the converter. On the other hand there would be the single level control structure in which both, the power distribution and the control of the converter, are integrated within the same level by using modern MPC control algorithms. Finally, three different case studies are presented to show the practical application of the developed control strategies together with the main conclusions of the thesis.Azken urteetan, ikerketa-lerro askok eraginkortasun energetikoa hobetzeko eta energia berriztagarriak garatzeko ahaleginak egin dituzte. Testuinguru honetan, energia metatze sistemen erabilera geroz eta handiagoa da, berriztagarrien integrazioa sare elektrikoarekin erraztu dezaketelako. Hala ere, energia altuko edo potentzia altuko metatze sistemak bakarrik aukeratu daitezke. Horregatik, ikertzaileek alternatiba berriak bilatzera behartuta daude. Energia metatze sistema desberdinen hibridazioa, arazo horri irtenbidea ematen dio. Honekin, potentzia eta energia maila altuak sistema bakar batetan batu daitezke. Tesi honen helburu nagusia, energia metatze sistema hibrido (HESS sigla, ingelesetik Hybrid Energy Storage System) bat diseinatzea eta inplementatzea da. Sistema honek, teknologia bakar batek eskaintzen duen errendimendua hobetzeko gai izan beharko luke. Lehen urratsa bezala, dokumentu honek literaturan aurkitutako topologia hibrido garrantzitsuenak laburbildu eta batzen ditu. Honi esker, konfigurazio bakoitzaren abantaila eta desabantailak hobeto ulertzea ahal da. HESS honen erabilera optimoa bermatzeko, ezinbestekoa da energia kudeatzeko estrategia on bat diseinatzea bihurgailu elektronikoaren kontrol egokiarekin batera. Horretarako, kontrol egitura ikuspegi desberdinetatik aztertuko da. Alde batetik, maila anitzeko kontrol egitura klasikoa egongo litzateke, normalean hiru mailaz osatua dagoena. Goi mailan funtzionamendu eta segurtasun mugak egongo lirateke, erdiko mailan potentzia banaketa, eta azkenik bihurgailuaren maila baxuko kontrola. Bestalde, maila bakarreko kontrol egitura egongo litzateke non mugak, potentzia banaketa eta bihurgailuaren kontrola maila berean integratzen dira kontrol iragarleko algoritmoen bidez (MPC). Azkenik, hiru kasu desberdin aurkezten dira garatutako kontrolen aplikazio praktikoa erakusteko tesiaren ondorio nagusiekin batera.En los últimos años, numerosas líneas de investigación han centrado sus esfuerzos en mejorar la eficiencia energética junto con el desarrollo de fuentes de generación renovables. En este contexto, el uso de sistemas de almacenamiento de energía está al alza, ya que estos pueden contribuir a la integración de las renovables en la red eléctrica convencional. Sin embargo, la necesidad de elegir entre dispositivos de alta energía o alta potencia, obliga a los investigadores a buscar otras alternativas. La hibridación de diferentes sistemas de almacenamiento se presenta como una solución apropiada para este problema, ya que combina alta energía y alta potencia dentro de un mismo sistema. El objetivo principal de esta tesis es el diseño e implementación de un sistema híbrido de almacenamiento de energía (sigla HESS, del inglés Hybrid Energy Storage System), capaz de mejorar las prestaciones que proporcionaría el uso de una única tecnología. Como primer paso en esta dirección, en este documento resume y clasifica las topologías de hibridación más relevantes encontradas en la literatura. Esto permite una mejor comprensión de los beneficios e inconvenientes de cada configuración. Para garantizar el uso óptimo de dicho HESS, es esencial diseñar una estrategia adecuada de gestión de energía junto con un control óptimo del convertidor electrónico de potencia. Para lograr este fin, la estructura de control ha sido analizada desde diferentes enfoques. Por un lado se encontraría la estructura de control multinivel clásica, la cual generalmente consta de tres niveles. En el nivel más alto se encontrarían las restricciones operativas y de seguridad, en el intermedio se encontraría la división de potencia, y por último el control de nivel bajo del convertidor. Por otro lado, se encontraría la estructura de control de un único nivel, en la que tanto las restricciones, el reparto de potencia y el control del convertidor se integran dentro del mismo nivel mediante algoritmos de control predictivo (MPC). Finalmente, se presentan tres casos de estudio para mostrar la aplicación práctica de las estrategias de control desarrolladas junto con las principales conclusiones de la tesis