Efficiency improvement of LDO ouput based linear regulator with supercapacitor energy recovery - a versatile new technique with an example of a 5v to 1.5 v version

Supercapacitors are used in various industrial applications and the supercapacitors technology is gradually progressing into a mature state. Common applications of supercapacitors are in electric vehicles, hybrid electric vehicles, uninterruptible power supply (UPS) and in portable devices such as cellular phones and laptops. The capacitance values range from fractional Farads to few thousand Farads and their continuos DC voltage ratings are from 2V to 6V. At University of Waikato, a team works on using supercapacitors for improving the efficiency of linear voltage regulators. In particular, this patented technique aims at combining off the shelfs LDO ICs and a supercapacitor array for improving end to end efficiency of linear regulator. My work is aimed at developing the theoretical background and designing prototype circuitry for a voltage regulator for the case of unregulated input supply is more than 3 times of the minimum input voltage requirement of the LDO which is applicable for a 5V to 1.5V regulator. Experimental results are indicated with future suggestions for improvement

Efficiency Improvement of LDO Output Based Linear Regulator With Supercapacitor Energy Recovery – A versatile new technique with an example of a 5V to 1.5V version

Supercapacitors are used in various industrial applications and the supercapacitors technology is gradually progressing into a mature state. Common applications of supercapacitors are in electric vehicles, hybrid electric vehicles, uninterruptible power supply (UPS) and in portable devices such as cellular phones and laptops. The capacitance values range from fractional Farads to few thousand Farads and their continuos DC voltage ratings are from 2V to 6V. At University of Waikato, a team works on using supercapacitors for improving the efficiency of linear voltage regulators. In particular, this patented technique aims at combining off the shelfs LDO ICs and a supercapacitor array for improving end to end efficiency of linear regulator. My work is aimed at developing the theoretical background and designing prototype circuitry for a voltage regulator for the case of unregulated input supply is more than 3 times of the minimum input voltage requirement of the LDO which is applicable for a 5V to 1.5V regulator. Experimental results are indicated with future suggestions for improvement

Analysis on Supercapacitor Assisted Low Dropout (SCALDO) Regulators

State-of-the-art electronic systems employ three fundamental techniques for DC-DC converters: (a) switch-mode power supplies (SMPS); (b) linear power supplies; (c) switched capacitor (charge pump) converters. In practical systems, these three techniques are mixed to provide a complex, but elegant, overall solution, with energy efficiency, effective PCB footprint, noise and transient performance to suit different electronic circuit blocks. Switching regulators have relatively high end-to-end efficiency, in the range of 70 to 93%, but can have issues with output noise and EMI/RFI emissions. Switched capacitor converters use a set of capacitors for energy storage and conversion. In general, linear regulators have low efficiencies in the range 30 to 60%. However, they have outstanding output characteristics such as low noise, excellent transient response to load current fluctuations, design simplicity and low cost design which are far superior to SMPS. Given the complex situation in switch-mode converters, low dropout (LDO) regulators were introduced to address the equirements of noise-sensitive and fast transient loads in portable devices. A typical commercial off-the-shelf LDO has its input voltage slightly higher than the desired regulated output for optimal efficiency. The approximate efficiency of a linear regulator, if the power consumed by the control circuits is negligible, can be expressed by the ratio of Vo/Vin. A very low frequency supercapacitor circulation technique can be combined with commercial low dropout regulator ICs to significantly increase the end-to-end efficiency by a multiplication factor in the range of 1.33 to 3, compared to the efficiency of a linear regulator circuit with the same input-output voltages. In this patented supercapacitor-assisted low dropout (SCALDO) regulator technique developed by a research team at the University of Waikato, supercapacitors are used as lossless voltage droppers, and the energy reuse occurs at very low frequencies in the range of less than ten hertz, eliminating RFI/EMI concerns. This SCALDO technique opens up a new approach to design step-down, DC-DC converters suitable for processor power supplies with very high end-to-end efficiency which is closer to the efficiencies of practical switching regulators, while maintaining the superior output specifications of a linear design. Furthermore, it is important to emphasize that the SCALDO technique is not a variation of well-known switched capacitor DC-DC converters. In this thesis, the basic SCALDO concept is further developed to achieve generalised topologies, with the relevant theory that can be applied to a converter with any input-output step-down voltage combination. For these generalised topologies, some important design parameters, such as the number of supercapacitors, switching matrix details and efficiency improvement factors, are derived to form the basis of designing SCALDO regulators. With the availability of commercial LDO ICs with output current ratings up to 10 A, and thin-prole supercapacitors with DC voltage ratings from 2.3 to 5.5 V, several practically useful, medium-current SCALDO prototypes: 12V-to-5V, 5V-to-2V, 5.5V-to-3.3V have been developed. Experimental studies were carried out on these SCALDO prototypes to quantify performance in terms of line regulation, load regulation, efficiency and transient response. In order to accurately predict the performance and associated waveforms of the individual phases (charge, discharge and transition) of the SCALDO regulator, Laplace transform-based theory for supercapacitor circulation is developed, and analytical predictions are compared with experimental measurements for a 12V-to-5V prototype. The analytical results tallied well with the practical waveforms observed in a 12V-to-5V converter, indicating that the SCALDO technique can be generalized to other versatile configurations, and confirming that the simplified assumptions used to describe the circuit elements are reasonable and justifiable. After analysing the performance of several SCALDO prototypes, some practical issues in designing SCALDO regulators have been identified. These relate to power losses and implications for future development of the SCALDO design

Design and development of auxiliary components for a new two-stroke, stratified-charge, lean-burn gasoline engine

A unique stepped-piston engine was developed by a group of research engineers at Universiti Teknologi Malaysia (UTM), from 2003 to 2005. The development work undertaken by them engulfs design, prototyping and evaluation over a predetermined period of time which was iterative and challenging in nature. The main objective of the program is to demonstrate local R&D capabilities on small engine work that is able to produce mobile powerhouse of comparable output, having low-fuel consumption and acceptable emission than its crankcase counterpart of similar displacement. A two-stroke engine work was selected as it posses a number of technological challenges, increase in its thermal efficiency, which upon successful undertakings will be useful in assisting the group in future powertrain undertakings in UTM. In its carbureted version, the single-cylinder aircooled engine incorporates a three-port transfer system and a dedicated crankcase breather. These features will enable the prototype to have high induction efficiency and to behave very much a two-stroke engine but equipped with a four-stroke crankcase lubrication system. After a series of analytical work the engine was subjected to a series of laboratory trials. It was also tested on a small watercraft platform with promising indication of its flexibility of use as a prime mover in mobile platform. In an effort to further enhance its technology features, the researchers have also embarked on the development of an add-on auxiliary system. The system comprises of an engine control unit (ECU), a directinjector unit, a dedicated lubricant dispenser unit and an embedded common rail fuel unit. This support system was incorporated onto the engine to demonstrate the finer points of environmental-friendly and fuel economy features. The outcome of this complete package is described in the report, covering the methodology and the final characteristics of the mobile power plant

Wireless voice amplification device for weak patients

Abstract – One problem that nurses and doctors face when treating a very weak patient is difficulty of communication. Sometimes patients become so weak that they are barely able to speak above a whisper without completely exerting themselves. Often nurses will have to put their ear directly in front of a patient’s mouth in order to hear what the patient is saying over the ambient noise in a hospital room. This becomes an even bigger problem when several patients are together in a single room and the ambient noise levels rise. One way to solve this problem would be to develop a wireless audio system to amplify the patient’s voice so that the doctors and nurses are able to hear and understand a patient who is speaking just above a whisper. There currently exists no off-the-shelf solution tailored to this specific problem. Most wireless audio systems are designed for public speaking, karaoke, or telephony, and do not work well for the problem described above. There is no self-contained of-the-shelf solution that would solve the problem well enough to be implemented on a large scale. This paper examines the problem of wireless audio amplification in a hospital room setting and proposes a practical solution in the form of a self-contained wireless voice amplification system

Modelling and thermal analysis of a seismic borehole sensor: diploma 2015

Analysis and adaptation of an acquisition system for a seismometer to enable operation at high temperatures (up to 180 [°C]). The simulation software and thermal measurements are used to validate theoretical results

An accurate, trimless, high PSRR, low-voltage, CMOS bandgap reference IC

Bandgap reference circuits are used in a host of analog, digital, and mixed-signal systems to establish an accurate voltage standard for the entire IC. The accuracy of the bandgap reference voltage under steady-state (dc) and transient (ac) conditions is critical to obtain high system performance. In this work, the impact of process, power-supply, load, and temperature variations and package stresses on the dc and ac accuracy of bandgap reference circuits has been analyzed. Based on this analysis, the a bandgap reference that 1. has high dc accuracy despite process and temperature variations and package stresses, without resorting to expensive trimming or noisy switching schemes, 2. has high dc and ac accuracy despite power-supply variations, without using large off-chip capacitors that increase bill-of-material costs, 3. has high dc and ac accuracy despite load variations, without resorting to error-inducing buffers, 4. is capable of producing a sub-bandgap reference voltage with a low power-supply, to enable it to operate in modern, battery-operated portable applications, 5. utilizes a standard CMOS process, to lower manufacturing costs, and 6. is integrated, to consume less board space has been proposed. The functionality of critical components of the system has been verified through prototypes after which the performance of the complete system has been evaluated by integrating all the individual components on an IC. The proposed CMOS bandgap reference can withstand 5mA of load variations while generating a reference voltage of 890mV that is accurate with respect to temperature to the first order. It exhibits a trimless, dc 3-sigma accuracy performance of 0.84% over a temperature range of -40°C to 125°C and has a worst case ac power-supply ripple rejection (PSRR) performance of 30dB up to 50MHz using 60pF of on-chip capacitance. All the proposed techniques lead to the development of a CMOS bandgap reference that meets the low-cost, high-accuracy demands of state-of-the-art System-on-Chip environments.Ph.D.Committee Chair: Rincon-Mora, Gabriel; Committee Member: Ayazi, Farrokh; Committee Member: Bhatti, Pamela; Committee Member: Leach, W. Marshall; Committee Member: Morley, Thoma

USB-C Power Adapter for DC House Project

Despite the importance of electricity and the impact it has on our daily lives, many people around the world still live without this essential utility today. According to the International Energy Agency (IEA), approximately 1.1 billion people in the world did not have access to electricity in 2017. The DC House Project at Cal Poly aims to provide electricity to people living in rural areas by directly utilizing DC energy generated from renewable or human powered sources without the need for DC-AC conversions. However, one significant issue is the lack of a standardized DC wall socket. Standards for AC wall sockets exist in different countries around the world making it simple for consumers to power their appliances and electronics. No such standard currently exist for DC power delivery to consumer devices. This makes DC power within the house inconvenient for consumers as there is no single plug that all their electronic devices can share. In pursuit of the DC House Project’s overall goal, our project is to design and build a USB-C Power Adapter for the DC House Project. The power adapter will interface with the DC House’s existing 48VDC infrastructure to deliver up to 100W at 20V to various electronic loads, such as laptops. Although USBC is a new and emerging technology, it is well placed to become a standard for DC power delivery. IHS technology projects that USB-C will be utilized in nearly five billion devices by 2021. Additionally, Apple vouched for the versatility of USB-C’s power delivery capability by replacing all of the ports on their current laptops, including the charging port, with USB-C ports. Thus, this project aims to standardize the wall socket utilized within the DC House Project and potentially other DC powered homes so that DC power can be as convenient for consumers as AC power

Design of a wireless monitoring system based on the ZigBee protocol for photovoltaic systems

This thesis was submitted for the degree of Master of Philosophy and awarded by Brunel University.This work deals with the possibility of using the promising technology of wireless sensor networks (WSN) in the field of photovoltaic (PV) plant supervising and monitoring. The knowledge of the status and good working condition of each PV module separately as well as of any component of the PV system will guide in a more efficient way of power management. This work will concentrate on monitoring and controlling as well as healthy operation control of PV panels separately. Data logging will be also available and can be used for reference or statistical purposes. The nature of wireless sensor networks (WSN) offers several advantages on monitoring and controlling applications over other traditional technologies including self-healing, self-organization, and flexibility. The versatility, ease of use, and reliability of a mesh network topology offered by the ZigBee technology that is based on the IEEE 802.15.4 standard, are used in this work to offer the maximum of its capabilities on the system being presented. A set of sensors attached on each PV panel are connected to a wireless ZigBee module. Each PV panel has its own ZigBee device located at its back side. All ZigBee devices forms a network with all the necessary devices of the ZigBee protocol included, such as end devises (RFD), a router (FFD), and a coordinator (COO). An extra ZigBee device might optionally be used to serve the whole system as an Ethernet gateway for making the system able to be connected to the internet. The factors that are being monitored are the panel‟s temperature, the output voltage, and output current. At the router device that operates as a parent for all the end devices, extra monitored factors are the air dust concentration, current irradiance and also the angle of the PV array (in the case of tracking system use).Two controlling outputs (relays) are located at the router device offering the capability of controlling the motors or the actuators of a tracking system

IoT on Shared Vehicles

Nowadays the need of people to have the power to control everything is increasing. Due to the technological evolution together with the Internet of things, this is already possible. In this context, the shared vehicles are a good example. With just one click people can use a vehicle from a vehicle sharing eet anywhere, anytime. During the realization of this project the uMDC was developed. It is a small device capable of managing and controlling di erent types of vehicles, with the main focus being the electric bicycles. As a nal conclusion of the project, the results obtained with the uMDC have proved very attractive. During its integration in the electric bicycles, the system was capable of controlling the bicycle's di erent components, as required for the rst prototype.Hoje em dia, a necessidade das pessoas terem controlo sobre tudo está a aumentar. Devido á evolução tecnológica juntamente com a Internet das coisas, isso já é possível. Neste contexto, os veículos partilhados são um bom exemplo disso. Com um simples clique, as pessoas podem usufruir e uma viatura de uma frota de veículos partilhados em qualquer lugar, a qualquer hora. Durante a realização deste projeto, foi desenvolvido o uMDC. Um pequeno ispositivo capaz de gerir e controlar diferentes tipos de veículos, sendo o foco principal as bicicletas elétricas. No nal deste projeto, os resultados obtidos com o uMDC foram bastante satisfatórios. Durante a sua integração nas bicicletas elétricas, o sistema foi capaz de controlar diferentes componentes das mesmas, como requerido para primeiro protótipo