Novel Solutions to Mitigate the Switching Noise in Power Circuit Applications

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An Adaptive Method to Reduce Undershoots and Overshoots in Power Switching Transistors Through a Low Complexity Active Gate Driver

Active gate drivers lend themselves well to reducing over- and under- voltages during the commutations of hard switched power transistors, as well as to damping resonances. However, their control strategy is a major challenge, as it should account for variations of operating condition, parameter spread, and non linearities of the driven transistor. This paper proposes an effective control method to reduce overshoots and undershoots in a power transistor driven by an active gate driver. The modulation pattern is modified on-the-fly and none a-priori characterization is required. The presented method modifies the timing parameter to attain almost zero over- and under- voltages with the lowest power losses. This is achieved by combining a low complexity active gate driver with the measurements of peak values of the drain-source voltage. The technique was experimentally assessed for a 48-12 V DC-DC converter, and resulted in better switching performance than standard solutions and open loop control

Investigations on the Use of the Power Transistor Source Inductance to Mitigate the Electromagnetic Emission of Switching Power Circuits

With power designers always demanding for faster power switches, electromagnetic interference has become an issue of primary concern. As known, the commutation of power transistors is the main cause of the electromagnetic noise, which can be worsened by the presence of unwanted oscillations superimposed onto the switching waveforms. This work proposes a solution to mitigate the oscillations caused by the turn-on of a power transistor by exploiting its source inductance plus an external one. In this context, an optimization method is proposed to find the optimal value of the source inductance as a trade-off between oscillation damping and power dissipation. The experimental results performed on a prototyped power converter assess the proposed technique as the spectrum of the conducted emission is attenuated by 20 dB at the oscillation frequency. With respect to traditional solution based on snubbers, the proposed solution results in a similar oscillation damping, but with a 0.5% higher power efficiency

A Wireless Communication System for Urban Water Supply Networks Based on Guided Acoustic Waves

The structural complexity of real-world pipeline networks makes it difficult to derive physics-based models of acoustic propagation. This work deals with the design of a communication system based on the propagation of acoustic waves in water-filled pipes. A method based on the experimental characterization of the communication channel is proposed. This approach is applied to an urban water distribution pipeline, and a black-box model representing its frequency response is obtained. The derived two-port model is used for the simulation of a complete communication system, comprising transmitter and receiver models, with the aim of using the water pipe as a wireless communication channel. It is shown that the choice of modulation parameters is critical in order to deal with issues such as the frequency selectivity of the channel and multipath wave propagation. A communication system is presented and the experimental results of the communicated data are provided

From Radio to In-Pipe Acoustic Communication for Smart Water Networks in Urban Environments: Design Challenges and Future Trends

The smart management of water resources is an increasingly important topic in today’s society. In this context, the paradigm of Smart Water Grids (SWGs) aims at a constant monitoring through a network of smart nodes deployed over the water distribution infrastructure. This facilitates a continuous assessment of water quality and the state of health of the pipeline infrastructure, enabling early detection of leaks and water contamination. Acoustic-wave-based technology has arisen as a viable communication technique among the nodes of the network. Such technology can be suitable for replacing traditional wireless networks in SWGs, as the acoustic channel is intrinsically embedded in the water supply network. However, the fluid-filled pipe is one of the most challenging media for data communication. Existing works proposing in-pipe acoustic communication systems are romising, but a comparison between the different implementations and their performance has not yet been reported. This paper reviews existing works dealing with acoustic-based ommunication networks in real large-scale urban water supply networks. For this purpose, an overview of the characteristics, trends and design challenges of existing works is provided in he present work as a guideline for future research

A Baseband Wireless VNA for the Characterization of Multi-Port Distributed Systems

Frequency characterization of spatially-large structures has become increasingly required, mostly in the fields of Structural Health Monitoring and Communication Systems based on non conventional media. When the ports of the system under measurement are far apart, methods based on traditional wired instruments become unattractive for field applications, due to the increased complexity, cost and signal integrity related issues. Aiming towards removing the wired connection from the ports of the system under test and the elaboration unit, the main issue to be dealt with is the time-synchronization of measurements at the ports. This contribution proposes a solution to such an issue by presenting a Wireless Vector Network Analyzer, suitable for the characterization of distributed systems. For this purpose, a wireless synchronization scheme is proposed, which is based on the disciplining of the signal sampling clock from the 1-Pulse-Per-Second reference signal. The proposed synchronization method reduces clock jitter at different ports at 1.13 μs over a 300 s observation interval. The hardware and software implementation of the system are detailed and experimental results proving its operation are provided

PROMET&O: A Multidisciplinary Approach to Monitor Indoor Environmental Quality

Recent studies have explored the influence of Indoor Environmental Quality (IEQ) on the occupants’ perception, behavior and productivity at work [1]. Also, it has been proved that a poor IEQ may turn in negative further consequences on occupants also affecting mental comfort and health [2]. The assessment of IEQ is thus a complex task due to its nature that considers the thermal, air quality, lighting and acoustics domains at the same time. Alongside with these aspects, there is no evidence of the extent to which exposure to day-to-day low-frequency electromagnetic fields may arise long term health issues, although international guidelines specify exposure limits for work places. Recent works, such as [3], have also investigated the use of Wireless Sensor Networks (WNSs) for air pollution monitoring, however, they typically refer to urban environment. To sum up, multi-domain investigations are therefore needed, and the use of accurate devices for the acquisition of objective IEQ metrics is mandatory. This research aims at developing an innovative, accurate and low-cost system for the in-field monitoring of IEQ, i.e., the so called PROMET&O system. With respect to the current state of the art, PROMET&O will provide the integration of the measured IEQ metrics with feedback of the perceived Indoor Environmental Comfort (IEC) from occupants, encouraging best practices for energy saving. The proposed system architecture is shown in Fig. 1 and consists in several Multi-Sensors (MSs) collecting data related to the IEQ metrics to be monitored, which are sent to an open-access platform for further processing. Each MS is provided with a set of sensors, whose outputs are periodically sampled by a controller, shown in Fig. 2. Sensors have been selected being low-cost, low-power and small-sized. The respective measurement range and accuracy are reported in Tab. 1 and agree with the specific IEQ standards. To avoid self-heating or cross-sensitivity issues, a first placement of the MS layout is proposed as shown in Fig. 3. Based on the sampled data, statistics of the measured quantities are evaluated and transferred to the server to be stored in a database. Future work will focus on further development and experimental validation of such system in an open space offices to correlate IEQ measured metrics with occupants’ feedback

Development and Metrological Characterization of a Multi-sensor Device for Indoor Environmental Quality (IEQ) monitoring

Indoor Environmental Quality (IEQ), which affects people's health, comfort, well-being and productivity, combines thermal, visual, acoustic and air quality conditions. This work deals with design, development and metrological characterization of a low-cost multi-sensor device that is able to detect the quality conditions of indoor environments for IEQ purposes. The device, hereafter referred as PROMET&O (PROactive Monitoring for indoor EnvironmenTal quality & cOmfort) embeds a set of low-cost sensors that measure air temperature and relative humidity, illuminance, sound pressure level, carbon monoxide, carbon dioxide, particulate matter, formaldehyde, and nitrogen dioxide. The basic architecture of the device is described and the design criteria that are related to the measurement requirements are highlighted. Particular attention has been paid towards the traceability assurance of the measurements provided by PROMET&O by means of specifically conceived calibration procedures, which have been tailored to the requirements of each measurement quantity. The calibration is based on the comparison to reference standards following commonly employed or ad-hoc developed technical procedures. The defined calibration procedures can be applied both for the single sensors and for the set of sensors integrated in the multi-sensor case. For the latter, the effects of the percentage of permeable case surface and the sensors allocation are also investigated. A preliminary uncertainty evaluation of the proposed multi-sensor device is reported for the carbon dioxide and the illuminance sensors taking the defined calibration procedures into account

A Low-Cost, Small-Size, and Bluetooth-Connected Module to Detect Faults in Rolling Bearings

Condition monitoring techniques have been successfully applied to detect damaged bearings. However, the signal acquisition and the subsequent processing are typically outsourced to expensive data acquisition boards and complex software, resulting in expensive solutions. As a side effect, the integration of condition monitoring systems in wireless sensor networks can be tough to achieve. Aiming to overcome such issues, a low-cost and small-size electronic module to be placed in the proximity of the bearing to be monitored was developed. The acoustic signal delivered by the bearing is acquired, and the corresponding frequency spectrum is evaluated on-board. Based on that, the developed module automatically detects the presence of defects and notifies the remote controller via a wireless connection only when a fault is detected, thus avoiding the use of data cables whilst minimizing the amount of transferred data. Experimental tests carried out on the proposed system assessed the accuracy of the evaluated frequency spectrum, resulting in an amplitude error within ±0.6%, as well as the fault detection capability in the presence of environmental acoustic noise

A Low Complexity Active Gate Driver to Damp the Oscillations Caused by Switching Power Transistors

The reduction of overshoots/undershoots and oscillations affecting the switching waveforms in hard-switched power circuits can be achieved by exploiting Active Gate Drivers (AGDs). The ones proposed so far are featured by a large number of driving levels and time intervals, resulting in time consuming optimization procedures. In this work, an AGD featuring two degrees of freedom is proposed and its effectiveness is experimentally validated. To this purpose, the undershoot affecting the drain-source voltage is considered as an indirect measure of oscillation damping at the power transistor turn-on