Measuring the flow rate and direction of gas flow in natural gas pipelines is of interest to both the management of gas delivery systems and the determination of consumer usage and payment. To improve on methods for measuring gas-flow rate and direction, researchers at UC Berkeley have developed microfabricated, ultrasonic gas-flow sensors. These innovative sensors are inexpensive, small and have modest power requirements -- making them suitable for wireless implementation. Moreover, these sensors can be mounted so that they don't intrude within the inner surface of a pipe, and therefore don't impede the conventional use of pipe cleaning (pigs) that fill the diameter of pipes.  (more...)

Power companies have expressed an opportunity for massive numbers of voltage sensors for monitoring high-voltage transmission and distribution lines as well as high-voltage equipment. In addition to monitoring operating status, these massive networks of high-voltage sensors could be used for a variety of novel applications such as monitoring sag as power lines heat-up and monitoring vegetation growth that could lead to arcing fires. However, to implement this vision, the voltage sensors need to be very inexpensive to make, deploy, maintain and operate. To address this opportunity, researchers at UC Berkeley have developed AC sensor solutions for high-voltage applications. These Berkeley AC voltage sensor solutions are MEMS-based for low-cost manufacturing, self-powered for low-cost maintenance, wirelessly networked for easy operation, package for all-weather environments, and they operate by proximity not galvanic coupling -- so they are easy to install. (more...)

There is strong commercial potential in the use of piezoelectric crystals for AC electricity sensors and in energy scavenging from nearby energized conductors. However, the widespread adoption of piezoelectrics in these applications is predicated on low cost of ownership including long lifecycles that don't require maintenance -- such as replacing batteries or failed parts. Therefore, improving the duration of the no-maintenance lifecycle of this technology strengthens its market potential for broad commercial penetration. To address this opportunity, researchers at UC Berkeley have developed a means of dynamically adjusting the operating properties of piezoelectric crystals used in AC electricity sensing and energy scavenging applications. This dynamic adjustment reduces the fatigue of piezoelectric crystals thereby promoting a longer lifecyle. In addition, the dynamic adjustments are implemented via circuit means -- instead of mechanical means that require relatively substantial power. (more...)

University researchers have designed topologies and control schemes that further simplify three-phase rectification circuits, demonstrating that the unified three-phase constant vector controller can be decoupled into two single-phase PFC controllers for two special groups of topologies. Therefore, the design of a three-phase PFC is dramatically simplified, furthermore all techniques and experiences used in single-phase PFC rectifier can be easily adopted by three-phase applications. (more...)

Without a distributed amplifier, most broadband amplifier bandwidths can be achieved around 1/10 to 1/3 of their fT only. Therefore, a high bandwidth amplifier requires high fT (at least 3-10 times of the amplifier bandwidth) transistors in order to achieve high bandwidth. Unfortunately, the current device technology is limited and in very high fT transistors, yield is still low. This leads to high cost and low yield.Even if high gain-bandwidth product could be achieved by a distributed amplifier, the major disadvantages of the distributed amplifier are large area, and high dc power consumption. Transistors were operated with high current density for high fT in order to achieve high bandwidth amplification. However, the transistors would become highly stressed resulting in reliability problems and short lifetimes. 50 ohm terminations are currently employed at the input and output of broadband amplifiers in order to obtain desirable input and output broadband impedance matches (low S11 and S22). However, the disadvantage is 3-dB losses at theirs inputs and outputs. (more...)

In order to improve energy efficiency and correspondingly lower energy use and cost, there is growing interest in improving the intelligence of electricity usage across the grid – including down to the level of common electronic devices that use single wire or two-wire “zip-cord”. To enable this ubiquitous level of intelligent electricity usage, AC current sensors will be needed that are inexpensive to make, simple to install, and easy to maintain. However AC current sensors with these attributes have not been developed. To address this challenge, researchers at UC Berkeley have developed an integrated sensor device that can measure AC electric current in a wire or wires that are operating in proximity to the device without requiring (1) electrical contact with, or physical encirclement of the conductors, or (2) precise spatial orientation or precise physical mounting/placement of the sensor device relative to the conductors. These attributes make the sensor inexpensive to manufacture, easy to install and simple to maintain. (more...)