Demetrio Iero

Heat flux sensor for power loss measurements of switching devices

The measurement of the power dissipated by a semiconductor device is of great importance for assessing system performance and reliability and to evaluate the overall efficiency of a power electronics systems. Efficiency measurement can be difficult when the device is highly efficient and the power losses are extremely low. Measurement errors can be introduced due to high frequency components in the waveforms. We present a calorimetric method based on a micromachined dual-sensor heat-flux measurement device that allows the estimation of the power dissipated by a semiconductor device. The system use a thermoelectric heat pump to keep the switching device at room temperature in order to minimise the heat exchanged with the ambient and improve therefore the precision of the measurement.

Heat flux-based sensor for the measurement of the power dissipated by switching devices

The precise measurement of the power dissipated by a semiconductor device operating in fast dynamic conditions is an important issue in power conversion circuits to evaluate their overall efficiency. Measurement errors can be introduced in particular by the probes or by instruments that are transparent to high dv/dt and di/dt rates. For this reason, the use of bulky and expensive set-ups is often required. We present a simple method based on a micromachined dual-sensor heat-flux measurement device, coupled to a readout circuit, that allows the estimation by calorimetry of the dissipated power. By means of a controlled Peltier heat pump, the switching device is held at room temperature in order to minimise the heat exchanged with the ambient and improve therefore the precision of the measurement. The sensor could be in principle integrated within the switching device case itself, to allow the lifelong monitoring of the produced heat.

A calorimetry-based measurement apparatus for switching losses in high power electronic devices

The measurement of the power dissipated by a semiconductor device is essential to evaluate the performance and reliability of power electronics systems. Power loss measurement can be difficult when the device is highly efficient and the losses are extremely low. When measuring the efficiency of an electronic system, many kind of errors can be introduced by the probes or by instruments and therefore the use of bulky and expensive set-ups are often required. The paper presents a simple method based on a heat flux measurement sensor that allows the estimation by calorimetry of the power dissipated by a semiconductor device. A control/readout circuit keeps the switching device at room temperature minimizing the heat exchanged with the ambient, improving the accuracy of the measurement.

SPICE modelling and experiments on a complete photovoltaic system including cells, storage elements, inverter and load

The design of a complete photovoltaic (PV) system and the precise evaluation of its performances under different conditions requires the use of an accurate simulation model. In this work, a SPICE model of a complete PV system, including a detailed model of PV cells and a multilevel inverter with load and energy storage elements, is presented. The simulation of the system as a whole allows determining the role of components and parameters as solar irradiation and cell temperature on the system performance. The global conversion efficiency and the total harmonic distortion (THD) of the output waveform are analysed in detail. The role and sizing criteria of storage elements placed in parallel with the PV modules are also analysed for various operating conditions. A PV system, including a specifically designed multilevel inverter, was built to perform efficiency and THD measurements that were compared with the simulation results to evaluate the model effectiveness.

RF-Powered HF-RFID Analog Sensors Platform

An RF powered UHF-RFID passive sensors platform was realized using discrete components and printed antennas designed to resonate at 868 MHz, used both for energy harvesting and data transmission. The tests demonstrate the possibility for the system to operate autonomously within the reading range of a standard RFID reader, that acts both as the RF power source and the receiver of the data stored in the tag user memory. The microcontroller can be interfaced on the same substrate with a sensor made of polymeric materials, sensible to physical parameters or chemical agents.

RF-powered UHF-RFID analog sensors platform

An RF powered UHF-RFID passive sensors platform was realized using discrete components and printed antennas designed to resonate at 868 MHz, used both for energy harvesting and data transmission. The tests demonstrate the possibility for the system to operate autonomously within the reading range of a standard RFID reader, that acts both as the RF power source and the receiver of the data stored in the tag user memory. The microcontroller can be interfaced on the same substrate with a sensor made of polymeric materials, sensible to physical parameters or chemical agents.

Using ANT Communications for Node Synchronization and Timing in a Wireless Ultrasonic Ranging System

Indoor localization and tracking of persons and assets for gaming, augmented reality, medical monitoring, training, security, and inventory is an emerging technology. Localization can be computed from multiple distance measurements between reference beacons and sensors. Low cost, small, light, tiny-battery, or even batteryless operated sensors are required. Ranging can be carried out by measuring the time of flight of an ultrasonic chirp traveling from an emitting beacon to receiving sensors. That requires a tight synchronization between the beacon and the sensors. In this article, we present a ranging system based on miniature commercial modules featuring ANT wireless personal area network communication plus onboard microprocessor. A protocol is developed for microseconds synchronization and accurate onboard ranging computations are carried out through ultrasonic signal cross correlation. The sensor privately computes its own range. The ranging system is composed of a synchronizing unit, a beacon emitting ultrasonic chirps, and a battery-operated distance sensor. The sensor shows low average power consumption (less than 22mW) and a ranging accuracy of about 1.8mm for distances up to 2.5 m, under stable environmental conditions.

A Calorimetry Based System for Measuring the Power Losses of Switching Power Devices

A system made of a custom designed heat flow sensor, a thermo-electric heat-pump, and a microcontroller based control board is presented for the measure of the power losses in power switches, e.g. MOSFETs or BJTs, operating in dynamic repetitive regime. The heat-flux sensor consists of two highly linear proportional to absolute temperature (PTAT) CMOS sensors. The thermoelectric module holds the case of the device under test at ambient temperature, so that heat entirely flows through the calorimeter. As the dissipated power measurement relies on the measurement of a heat flow, the apparatus is particularly suitable, and provides reliable results, in fast switching devices, regardless of the switching frequency, thus overcoming the problems associated with direct electrical measurements.

A measurement apparatus for switching losses based on an heat-flux sensor

The measurement of the power dissipated by a semiconductor device is essential to evaluate the performance and reliability of the device itself and those of the whole power electronics system. When measuring the efficiency of an electronic system, measurement errors can be introduced by the probes or by instruments due to high frequency components in the waveforms. Efficiency measurement can therefore be difficult when the device is highly efficient and the power losses are extremely low and the use of bulky and expensive set-ups is often required. The paper present a simple method based on a heat-flux measurement sensor that allows the estimation by calorimetry of the power dissipated by a semiconductor device. The system uses a Peltier heat pump and a control/readout circuit to keep the switching device at room temperature and minimise the heat exchanged with the ambient, improving the accuracy of the measurement.

One-shot SPICE simulation of photovoltaic modules, storage elements, inverter and load

A SPICE model of a complete photovoltaic (PV) system, including a detailed model of PV cells, a modified cascaded multilevel inverter, energy storage elements and load, is presented. Multi-level inverters suits particularly well PV systems and bring several advantages among which the lower switching speed of the switching elements, which in turn means less stress for these devices and a lower harmonic content in the output voltage. The simulation of the system as a whole allows evaluating readily the role of components, as well as of the solar irradiation and cell temperature. The global conversion efficiency and the total harmonic distortion (THD) of the output waveform are in particular analyzed. The role and sizing criteria of a storage element placed at the PV module output are also analyzed for various operating conditions. Experimental tests have been carried out on a photovoltaic system prototype and compared to those obtained with simulations.