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DC Circuit Breaker for Emerging Power Systems

Many non-traditional energy sources, such as solar panels, fuel cells, and batteries, supply direct-current (DC) power. This has led to development of DC power systems for a number of applications since conversion to alternating-current (AC) can be eliminated. For example, DC distribution is now used for computer data centers, office buildings, and ship power and propulsion. Though the source, loads, and other components in a DC power system are well understood, there may be interest in innovation with respect to protection schemes since DC systems do not have a zero crossing in its current, and circuit breakers are unable to open up a faulted component without sustaining an arc.

Biomimetic Chemical Compounds for Capturing Carbon Dioxide from Power Plant Stacks and the Atmosphere

Researchers at the University of California, Davis have developed synthetic biochemical compounds that capture carbon dioxide from the atmosphere or sources such as power plants. These new derivatives mimic how some plants capture carbon dioxide from the air and use it for photosynthesis.

Efficient Boost/Step-Up Direct Current-Direct Current (DC-DC) Converter

Renewable energy sources such as solar photovoltaics (PV) and wind turbines are used for clean power generation to address the ever-increasing energy consumption. With large-scale integration of renewables, battery storage becomes essential in the grid to meet supply-demand volatility. In these scenarios, direct current (DC) grids offer multiple benefits over alternating current (AC) grids such as, improved efficiency, controllability, reliability and reduced cost. Isolated voltage boost/step-up DC-DC converters are used for interfacing PV and wind energy sources with DC grids and DC-DC converters serve such applications and environments. Existing DC-DC converter designs have known weaknesses. For example, shunt-resonant converter capacitors require a dedicated charging interval in every switching half-cycle, which does not contribute towards energy transfer and results in duty-cycle loss. Since the shunt-resonant capacitor is designed to hold resonant energy sufficient for a rated current condition, resonant energy is fixed for all loading conditions. At reduced loading, reduced resonant energy is sufficient but shunt-configuration has no means to achieve this control. Although this may be mitigated by using two additional switches, this arrangement leads to increased losses and cost. At reduced loading, duty-cycle loss increases significantly because the reduced current results in longer capacitor charging time. This severely restricts the operation range of converter. Smooth current commutation and zero-current-switching (ZCS) are also lost at overload conditions since the capacitor is designed for rated-current condition. The shunt-resonant capacitor is expected to hold its voltage/energy during the operating mode when input inductor charges. However, a leakage path exists through the transformer winding parasitics, which results in capacitor discharge. As a result, the capacitor energy must be overrated to compensate for this loss, which further aggravates all of the aforementioned issues. In another example, series-resonant capacitors must also be charged to a voltage higher than the reflected voltage across the transformer-primary. Peak voltage-rating of primary-side components (e.g., switches and input inductor) is also increased. Series-resonant capacitor also transfers energy to the output during the time interval when resonant current commutation occurs, which requires using capacitors having a higher rating. At reduced loading, the series-resonant capacitor does not have enough voltage to satisfy the resonant condition. Switching frequency may be used as an additional control parameter without using extra switches. Reduction in switching frequency results in increased charging time and hence, higher voltage, while ripple content increases and requires larger filters due to varying switching frequency. Overall, while traditional DC-DC converters like the aforementioned meets some requirements, it may be desirable to have new DC-DC converter approaches to smoothly onboard and operate PV and wind energy production with DC grids.

(SD2020-249) Adaptive Bias Circuits For CMOS Millimeter-Wave Power Amplifiers: state-of-the-art back-off efficiency for silicon Ka-band Doherty PAs using single inputs and without digital predistortion

Power amplifier performance for emerging 5G mm-wave systems poses significant challenges for output power, efficiency and linearity. Efficiency in backoff is a key concern, given the peak-to-average power ratio of order 6-9dB for 5G signals. As a result, considerable attention has been given to composite amplifiers featuring backoff efficiency enhancement, particularly Doherty amplifiers. Adaptive bias circuits have been previously developed for use with power amplifiers at low microwave frequencies (for example, 1-2GHz as applied in 2G, 3G and 4G cellular networks).  Direct application of these techniques is not straightforward at higher frequencies, such as 28GHz as used for 5G wireless communications, because the transistors have less gain at the high frequencies. 

Scalable High Intensity Ultrashort Pulse Compressor And Cleaner

This invention is a high intensity ultrashort pulse compressor that filters out low intensity artifacts and is made with commercially available low-cost components. This integrated system also provides scalability and can therefore be used for a range of laser intensities.

Thin-Film Optical Voltage Sensor For Voltage Sensing

Researchers at UC Berkeley have developed techniques for optical voltage sensing of power grids as well voltage sensing within a human or animal subject. The safe, accurate and economical measurement of time-varying voltages in electric power systems poses a significant challenge. Current systems for measuring power grid voltages typically involve instrument transformers. Although these systems are accurate and robust to environmental conditions, they are bulky, heavy, and expensive, thus limiting their use in microgrids and sensing applications. An additional drawback is that some designs explode when they fail. Optical methods for direct measurement of high voltages have gained attention in recent years, mainly due to the high available bandwidth, intrinsic electrical isolation, and the potential for low cost and remote monitoring. Stage of Research The inventors have developed a low-Q resonant optical cavity-based voltage sensor based on a piezoelectric AIN thin film that transduces a voltage applied across the piezo terminals into a change in the resonant frequency of the cavity. This sensor can be fabricated with high yield and low cost (<$1), which makes it uniquely well-suited to reduce the cost of grid voltage measurement.

Spin-orbit Rectifier for Weak RF Energy Harvesting

The invention is a new rectifier/detector concept, simultaneously utilizing the Hall effect and spin-orbit torque. Both phenomena scales with the current density and improves inversely with the device cross-sectional area, providing the largest signals at the nanoscale. The invention injects RF current in a Hall material to generate a Hall voltage, and use the same RF current in a spin-orbit material to control a magnet, which then applies a magnetic field to the Hall material leading to a rectification of the Hall voltage. A magnet with low anisotropy energy is used to make it sensitive to low RF currents. The device and corresponding circuits in HSPICE use materials parameter for InAs as the Hall layer, Bi2Se3 as the spin-orbit (SO) layer, and a soft ferrite as the magnet, we calculate the DC voltage from a 200 nm thin device to be ~100 μV from a ~500 nW RF power. A series array of such devices that can improve the DC voltage to ~100 mV from the same RF power, while matching the receiver antenna impedance.

A Battery-Less Wirelessly Powered Frequency-Swept Spectroscopy Sensor

UCLA researchers in the Department of Electrical and Computer Engineering have developed a wirelessly powered frequency-swept spectroscopy sensor.

Scalable Manufacturing of Copper Nanocomposites with Tunable Properties

UCLA researchers in the Department of Mechanical and Aerospace Engineering have developed a cost-effective method to produce copper-based nanocomposites with excellent mechanical, electrical and thermal properties.

A Family Of Hybrid Boosting Voltage Converters

Many industries, such as solar cells and energy storage, will be greatly benefited by high-gain step-up/step-down converters.UCI researchers have developed a family of hybrid boosting converters (HBC) that combine a base bipolar voltage multiplier (BVM) and one of several possible inductive switching cores to address various converter functionalities.

A Family Of Two-Switch Boosting Switched-Capacitor Converters (TBSC)

Switched capacitor converters, which provide high-gain voltage conversion, have drawbacks that have limited their use to specific applications. UCI researchers have developed a family of two-switch boosting switched-capacitor converters (TBSC) that enables the use of switched-capacitor converters in low cost and small-size applications as well as on-chip integration.

Combination Of Air Lubrication And Super Hydrophobic Frictional Drag Reduction

This technology combines air layer frictional drag reduction (ALDR) with super hydrophobic surfaces (SHS) to achieve frictional drag reduction of ALDR with significantly reduced gas flux. Thus, enabling increased net energy savings. The stable air layer is achieved with lesser gas flux when utilizing a SHS.Periodic air layers may replenish SHS, enabling drag reduction with reduced energy cost. Combinations of SHS and regular or other non-SHS surface may be used to control spreading of gas, thus facilitating formation of ALDR using discrete gas injection points better than previously achievable. Such surface variations could also be used to preferentially guide gas towards or away from propulsion, depending on desired outcome. By controlling ALDR regionally or globally on a surface, with or without SHS, this technology modifies flow around a hull. This mediates forces on partially or fully submerged objects, enabling control of flow patterns, resistance, steering, and/or dynamics.

Half-Virtual-Half-Physical Microactuator

Researchers at the University of California, Davis have developed a half-virtual-half-physical microactuator that utilizes a combination of computational models and microelectromechanical systems for use in medical devices and mechanical systems.

Method Of Localizing Breakdown In High Power Rf Network

Researchers in the Department of Physics have developed a method for detecting localized electrical breakdowns in high power RF networks.

Clock Power Reduction Utilizing Adiabatic Charging Method Via a Switched-Capacitor Circuit

Normally, charging a capacitive load from a voltage source invokes a ½ CV2 energy penalty. The concept of adiabatic charging, where the capacitor is charged more slowly than nominally afforded by the natural RC time constant of the charging circuit in the pursuit of reducing energy dissipation to below ½ CV2, has been around for decades. However, there has not been any solution to enabling this slow charging phenomenon in a practical, low-overhead embodiment. For example, prior work used separate DC-DC converters to provide multiple voltage levels, or used resonant inductors, both of which invoke significant area overhead.

A CMOS Compatible Fully-Integrated Switched-Domain Power Inverter Circuit

Modern mobile applications strive for the complete integration of all communication systems in CMOS. Unfortunately, it is conventionally difficult to efficiently generate high levels of RF power in scaled CMOS largely due to the inherently low voltage ratings of core transistors. To realize high output power with ~1V transistors, power combining techniques have been proposed whereby the output of several low-voltage power amplifier (PA) cells are combined via inductive transformers. However, power combining relies on ultra-thick metal that still carries large ohmic and substrate losses. These AC-AC losses, combined with the DC-AC losses of the PAs themselves, and the DC-DC losses of the battery-connected power converters, result in limited total transmitter efficiencies. Even modern digital PA techniques such as RF-DACs, digital Doherty, and digital out-phasing, which have been proposed to leverage the excellent switch performance of scaled transistors and offer reconfigurable operation, still require battery-connected DC-DC converters and RF transformers/power combiners, both of which result in cascaded losses.

Operation Frequency Band Customizable and Frequency Tunable Filters with EBG substrate

The technology relates to cavity resonators and filters for improved processing of electromagnetic signals. Specifically, the invention is a cavity resonator or filter that is constructed on electromagnetic bandgap substrate that includes an external controlling assemble can change the work frequency of the cavity resonator or filter. This enables device access to frequencies with a very broad range.

Improved Energy Harvesting for Current-Carrying Conductors

There are an estimated 130 million wooden poles that support overhead power lines in the US.  Extreme weather, aging, storms or sabotage can all lead to potential damage of these poles and power lines, which can leave large areas without basic necessities.  Due to this risk, it’s anticipated that power utility companies will deploy sensors and corresponding energy harvesters to better respond to potential damage of this critical electricity grid infrastructure. To address this anticipated mass deployment of sensors and harvesters, researchers at UC Berkeley have developed technology improvements to harvesting of electrical energy from energized conductors carrying alternating currents, such as those on overhead and underground power lines (as well as power-supplying conductors in offices and dwellings).  These enhanced harvesters would improve the economics of deploying sensors across a national power grid.  The Berkeley harvesters can readily provide enough power to supply wireless communication devices, energy storage batteries and capacitors, as well as sensors such as accelerometers, particulate matter measuring devices, and atmospheric sensors.

A Highly-Efficient Near-Field Wireless Power Transfer System That Is Immune To Distance And/Or Coupling-Coefficient Variations

UCLA researchers in the Department of Electrical Engineering have developed a novel design for a wireless power transfer system. This new design is optimized to function stably over a greater and variable distance than current systems and to function with a higher efficiency.

Signal Statistics Compression-Based Quantization Method in an ADC

The technology is a new architecture for analog-to-digital converters (ADCs).Its properties include the use of unique signal statistics compression quantization technique, lower power than other ADC techniques, no degradation of effective number of bits and conversion rate, and automatic adaption to power-optimized state of input signal.With this technology, users will be able to produce more power efficient ADCs

Methods for Fabrication of Electric Propulsion Tips

The technology is a method for fabrication of silicon microfabricated emitter tips.This process has two-step etching process which utilizes field emission electric propulsion (FEEP) and indium propellant.

Silicon On Sapphire Based Plasmonic And Metasuraface Design For Optical Light Manipulation

The technology is a high contrast optical grating.It features patterned silicon on sapphire and is designed for a broad range of optical frequencies: from visible to far infrared with ultra-high reflectivity.The technology can be tailored to mimic mirrors and other optical components.

GaN-based Vertical Metal Oxide Semiconductor and Junction Field Effect Transistors

The first true vertical GaN-based transistors, where gating is also performed on electrons traveling perpendicular to the surface in a vertical channel.

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