A reconfigurable dual output low power digital PWM power converter

This versatile power converter controller provides dual outputs at a fixed switching frequency and can regulate either output voltage or target system delay (using an external L-C filter). In the voltage regulation mode, the output voltage is monitored with an A/D converter, and the feedback compensation network is implemented digitally. The generation of the PWM signal is done with a hybrid delay line/counter approach, which saves power and area relative to previous implementations. Power devices are included on chip to create the two independently regulated output PWM signals. The key features of this design are its low power dissipation, reconfigurability, use of either delay or voltage feedback, and multiple outputs

Towards Very Large Scale Analog (VLSA): Synthesizable Frequency Generation Circuits.

Driven by advancement in integrated circuit design and fabrication technologies, electronic systems have become ubiquitous. This has been enabled powerful digital design tools that continue to shrink the design cost, time-to-market, and the size of digital circuits. Similarly, the manufacturing cost has been constantly declining for the last four decades due to CMOS scaling. However, analog systems have struggled to keep up with the unprecedented scaling of digital circuits. Even today, the majority of the analog circuit blocks are custom designed, do not scale well, and require long design cycles. This thesis analyzes the factors responsible for the slow scaling of analog blocks, and presents a new design methodology that bridges the gap between traditional custom analog design and the modern digital design. The proposed methodology is utilized in implementation of the frequency generation circuits – traditionally considered analog systems. Prototypes covering two different applications were implemented. The first synthesized all-digital phase-locked loop was designed for 400-460 MHz MedRadio applications and was fabricated in a 65 nm CMOS process. The second prototype is an ultra-low power, near-threshold 187-500 kHz clock generator for energy harvesting/autonomous applications. Finally, a digitally-controlled oscillator frequency resolution enhancement technique is presented which allows reduction of quantization noise in ADPLLs without introducing spurs.PhDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/109027/1/mufaisal_1.pd

Power quality disturbance mitigation in grid connected photovoltaic distributed generation with plug-in hybrid electric vehicle

In the last twenty years, electric vehicles have gained significant popularity in domestic transportation. The introduction of fast charging technology forecasts increased the use of plug-in hybrid electric vehicle and electric vehicles (PHEVs). Reduced total harmonic distortion (THD) is essential for a distributed power generation system during the electric vehicle (EV) power penetration. This paper develops a combined controller for synchronizing photovoltaic (PV) to the grid and bidirectional power transfer between EVs and the grid. With grid synchronization of PV power generation, this paper uses two control loops. One controls EV battery charging and the other mitigates power quality disturbances. On the grid connected converter, a multicarrier space vector pulse width modulation approach (12-switch, three-phase inverter) is used to mitigate power quality disturbances. A Simulink model for the PV-EV-grid setup has been developed, for evaluating voltage and current THD percentages under linear and non-linear and PHEV load conditions and finding that the THD values are well within the IEEE 519 standards

Microfluidic platforms for high-throughput mammalian cell printing, transfection, and dosage-dependent studies

With the advent of high-throughput and genome-wide screening initiatives, there is a need for improved methods for cell-based assays. Current approaches require expensive equipment, rely on large-scale culturing formats not suited for small or rare sample types, or involve tedious manual handling. Microfluidic systems could provide a solution to these limitations, since these assays are accessible, miniaturized, and automated. When coupled with high-content analysis, microfluidics has the potential to drastically increase throughput in cell biology and drug discovery. In light of these benefits, we developed 3 microfluidic approaches for mammalian cell-based assays: (1) printing of live mammalian cells into nanowell arrays, (2) a high-throughput transfection device, and (3) a module that generates complex, continuous concentration profiles. Our first technique generates high-density nanowell arrays of live mammalian cells (LMCAs) using a standard contact microarrayer. Both commonly used cell lines and primary cells cultured on the arrays are highly viable and maintain their signature phenotype, making the platform suitable for long-term stem cell differentiation studies. Our 675-well array is ~2.6x more dense than a 1,536-well microtiter plate and can be frozen and thawed, facilitating the handling, storage, and screening of large libraries of cells. LMCAs are also compatible with transfection, a technique that could enable analysis of the entire proteome in the natural cellular context. Transfection is routinely conducted on high-throughput arrays, but this setup requires manual cell culturing and precludes precise control over the cell environment. To this end, we created a microfluidic chip that streamlines cell loading and culturing and implements 280 independent transfections at up to 99% efficiency. The chip can perform co-transfections, in which the number of cells expressing each protein and the average protein expression level can be precisely tuned as a function of input DNA concentration. This platform is well-suited for optimizing synthetic gene circuits; we co-transfected four plasmids to test a histidine kinase signaling pathway and mapped the dose dependence of this network on the level of one of its constituents. The chip is readily integrated with high-content imaging, enabling the evaluation of cellular behavior and protein expression dynamics over time. To complement the biological assays that could be performed on our transfection chip, we lastly generated an accurate and automated method to manipulate molecular concentrations on chip. Our pulse-width modulation (PWM)-based microfluidic module combines up to 6 different inputs and produces arbitrary concentrations with a dynamic range of 3-5 decades. We created complex concentration profiles of 2 molecules, with each concentration independently controllable. The PWM module can execute rapid concentration changes as well as long-timescale pharmacokinetic profiles under a variety of operating conditions, making it ideal for integration with existing devices for advanced cell and pharmacokinetic studies. Taken together, the 3 microtechnologies developed in this work integrate and automate mammalian cell handling, culturing, transfection, imaging, and solution preparation. These features have far-reaching implications in fields such as synthetic biology, stem cell research, and drug development

Multi-Level Medium Voltage Inverter for Dc Distributed Wind Farm to Establish Grid Interface and Provide Ancillary Support

Wind energy has gained in popularity in recent years due to cost, security and environmental concerns associated with conventional energy sources like fossil fuels. However, the utilization of wind energy in power systems creates many technical and non-technical challenges that need to be addressed for successful integrations. The main technical issues related to wind energy are its uncertainty and variability and their impacts on stability, reliability and quality of the electric power. In systems with high wind energy penetrations, unlike conventional generations, sudden changes in active and/or reactive power demand cannot be supported by wind energy. This lack of demand support may create unwanted voltage and frequency variations in the grid. On the hand, the existing AC distributed wind farms have several drawbacks including complexity, higher cost, and lower efficiency. In this dissertation, a medium voltage direct current (MVDC) distribution system for wind farms is investigated. The proposed system offers higher reliability, lower cost, higher efficiency and more importantly grid support. It also allows for easier integration of energy storage systems at DC level. Design, control, implementation, and testing of a three-level medium voltage inverter are presented. The inverter can provide active and reactive power support to the grid in case of frequency and voltage droops. Simulation and experimental results are presented to verify the viability of the proposed system and control techniques

Static reactive power compensator design, based on three-phase voltage converter

At present, electrical network stability is of the utmost importance because of the increase in electric demand and the integration of distributed generation deriving from renewable energy. In this paper, we proposed a static reactive power compensator model with common direct current voltage sources. Converter parameters were calculated and designed to fulfill specifications. In order to ascertain the device response for different operating modes as reactive power consumer and generator, we developed the model’s power and control circuits in Matlab Simulink. Simulations were performed for different conditions, and as a result, the current and voltage waveforms and the circular power chart were obtained. This paper has theoretically proven it is possible to achieve the consumption or generation of purely active or reactive power by implementing a static reactive power compensator with common DC voltage sources. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Design and implementation of the Front End Board for the readout of the ATLAS liquid argon calorimeters

The ATLAS detector has been designed for operation at CERN's Large Hadron Collider. ATLAS includes a complex system of liquid argon calorimeters. The electronics for amplifying, shaping, sampling, pipelining, and digitizing the calorimeter signals is implemented on the Front End Boards (FEBs). This paper describes the design, implementation and production of the FEBs and presents measurement results from testing performed at several stages during the production process

Millimeter-Precision Laser Rangefinder Using a Low-Cost Photon Counter

In this book we successfully demonstrate a millimeter-precision laser rangefinder using a low-cost photon counter. An application-specific integrated circuit (ASIC) comprises timing circuitry and single-photon avalanche diodes (SPADs) as the photodetectors. For the timing circuitry, a novel binning architecture for sampling the received signal is proposed which mitigates non-idealities that are inherent to a system with SPADs and timing circuitry in one chip