An FPGA-Based Software Defined Radio Platform for the 2.4GHz ISM Band

A prototype of a Software Defined Radio (SDR) platform has been successfully designed and tested implementing a reconfigurable IEEE 802.11 and ZigBee receiver. The system exploits the reconfiguration capability of an FPGA for implementing a number of receiver configurations that share the same RF front-end. Configurations can be switched at run time, or can share the available logic and radio resource

An embedded diagnostic system for wheelchairs brushless drives monitoring

The implementation of a microcontroller based monitoring system for the diagnosis of a brushless synchronous motor drives is presented. It finds its primarily interest on motorized wheelchair for disabled people. The embedded system mainly controls all the principal parameters of the electrical drives together with the power supply system. Pre-failure and failure conditions are routinely logged and, depending on the malfunction severity, alarm messages are created and sent to a remote base station by using the GSM wireless network

GaN and SiC Device Characterization by a Dedicated Embedded Measurement System

This work proposes a comparison among GaN and SiC device main parameters measured with a dedicated and low-cost embedded system, employing an STM32 microcontroller designed to the purpose. The system has the advantage to avoid the use of expensive laboratory measurement equipment to test the devices, allowing to obtain their behavior in operating conditions. The following KPIs (Key Performance Indicators) are measured and critically compared: threshold voltage, on-resistance and input capacitance. All the measurements are carried out in a short time interval and on a wide range of switching frequencies, ranging from 10 kHz to 1 MHz. This investigation is focused on the deviation of the figures of merit when the switching frequency changes, since it is crucial for wide-bandgap devices. The devised, low-cost, microcontroller unit allows high flexibility and system portability, while the employed equivalent-time sampling technique overcomes some issues related to the need of high sampling frequency. It allows good performances with common microcontroller embedded AD converters. To validate the proposed system, the obtained results have been compared with the time-domain waveforms acquired with a traditional laboratory oscilloscope and a study of the system’s measurement errors has been carried out. Results show that GaN devices achieve a higher efficiency with respect to SiC devices in the considered range of switching frequencies. The on-resistance exhibited by GaN devices shows, as expected, an increase with frequency, which happens to switching losses, too. On the other hand, GaN devices are more sensitive to parasitic effects and the high dV/dt, due to the reduced switching times, can excite unwanted ringing phenomena

Low cost electrical current sensors with automatic measurement range

We present a simple and low cost Smart Current Sensor with wide automatic measurement range. The logic core system of the sensor is the Atmel AT32UC3C2256C AVR 32-bit microcontroller, the wireless core is a Microchip MRF24J40MA IEEE 802.15.4 RF transceiver[3]. The MCU features 11 ADC multiplexed channels, with 12-bit resolution and sample rate up to 2Msps, two of which can be sampled in parallel. The sensing board consists of two hall-effect based current sensors, assembled on different PCBs in order to perform with different sensitivities. Custom primary conductor design allowed us to sense the current flowing in the conductor with two different sensitivities: the sensor mounted inside the two PCBs gets a strong contribution from the traces on both the PCBs, the sensor mounted outside only gets a strong contribution from the traces on the bottom PCB

An Experimental Testbed and Methodology for Characterizing IEEE 802.11 Network Cards

It has been observed that IEEE 802.11 commercial cards produced by different vendors show a different behavior in terms of perceived throughput or access delay. Performance differences are evident both when the cards contend alone to the channel, and when heterogeneous cards contend together. Since the performance disaligment does not disappear by averaging the environmental factors (such as propagation conditions, laptop models, traffic generators, etc), it is evident that the well known throughput-fairness property of the DCF protocol is not guaranteed in actual networks. In this paper we propose a methodological approach devised to experimentally characterize the IEEE 802.11 commercial cards thus understanding and predicting their performances in different network scenarios. We set up some specific experiments using a custom test equipment, able to classify the card behavior not only in terms of figures which are evident to the user perspective (such as the throughput), but also in terms of low-level channel access operations and delays. Our approach is able to detect potential hardware limits or not-standard MAC implementations, which severely affect the contending card performance

Design and Performance Evaluation of a High Power-Density EMI Filter for PWM Inverter-Fed Induction-Motor Drives

This paper presents the design of an electromagnetic interference (EMI) filter for a low-voltage high-current induction-motor drives supplied by dc power grids. In order to effectively design the EMI filter, a suitable common-mode/differential-mode (CM/DM) separation technique has been used. Due to the high operating currents, the software-based separation technique using time-domain measurements has been applied. The proposed technique allows the CM and DM sections of the EMI filter to be properly selected in a more economical way, i.e., without the need of a dedicated hardware or costly radio frequency (RF) instrumentation. The design has been done according to a power-density criterion. The effectiveness of the proposed CM/DM separation technique and the EMI filter features/performance has been assessed by experimental tests, carried out with an 1.1-kW pulsewidth modulation (PWM) inverter-fed induction-motor drive, supplied by a 48-V dc power grid

Smart plugs: A low cost solution for programmable control of domestic loads

Balancing energy demand and production is becoming a more and more challenging task for energy utilities. This is due to a number of different reasons among which the larger penetration of renewable energies which are more difficult to predict and the meagre availability of financial resources to upgrade the existing power grid. While the traditional solution is to dynamically adapt energy production to follow the time-varying demand, a new trend is to drive the demand itself by means of Direct Load Control (DLC). In this paper we consider a scenario where DLC functionalities are deployed at a large set of small deferrable energy loads, like appliances of residential users. The required additional intelligence and communication capabilities may be introduced through smart plugs, without the need to replace older 'dumb' appliances. Smart plugs are inserted between the appliances plugs and the power sockets and directly connected to the Internet. An open software architecture allows to abstract the hardware sensors and actuators integrated in the plug and to easily program different load control applications

FILTRI EMI COMPATTI NEI CONVERTITORI ELETTRONICI DI POTENZA

The goal of the research recently started is to create efficient EMI filters compact that allow to obtain converters with low dimensions and economically competitive

PROGETTAZIONE OTTIMIZZATA DI FILTRI EMI AD ELEVATA POWER DENSITY PER CONVERTITORI ELETTRONICI DI POTENZA

In molti dei campi di impiego dei convertitori elettronici di potenza (aeronautico, aerospaziale, automotive, etc.) è richiesta la realizzazione di sistemi di conversione che, in relazione a stringenti vincoli di progetto, presentino, a parità di potenza, dimensioni sempre più compatte e pesi ridotti. In tale ottica, l’ottimizzazione della densità di potenza (power density) del convertitore diventa un obiettivo essenzial

Implementation and Comparison of SiC and GaN switches for EV Fast Recharging Systems

Wide bandgap material-based devices allow faster switching frequency and exhibit smaller losses than traditional Si devices; nevertheless, a complete understanding of the functioning of these new devices remains poorly understood. A fast battery charger for electric vehicles based on a converter employing SiC and GaN devices is here reported Besides, these two technologies are experimentally compared, in the same layout, to highlights their performance in terms of electrical dynamic and electromagnetic compatibility