1,720,987 research outputs found
Novel Solutions to Mitigate the Switching Noise in Power Circuit Applications
Get PDFL'abstract è presente nell'allegato / the abstract is in the attachmen
An Adaptive Method to Reduce Undershoots and Overshoots in Power Switching Transistors Through a Low Complexity Active Gate Driver
Get PDFActive 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
A Software-Based Control System to Reduce Conducted CM EMI in Four-Leg Three-Phase Inverters Using the Delay Compensation Technique
Get PDFCommon-Mode (CM) conducted Electro Magnetic Interference (EMI) is a critical issue in automotive power converters, where strict EMC regulations must be met. This paper investigates the Delay Compensation Technique (DCT) applied to traction inverters to reduce CM EMI at low-frequency. Although the four-leg topology enables complementary switching, existing works do not provide a method to finely align the commutation edges, which is required to have CM current pulses canceling out and effectively reducing CM EMI. In this work, an iterative optimization method is introduced for the two-leg case, and then extended to the four-leg inverter with sinusoidal modulation, enabling fast convergence and minimal computational overhead. Experimental validation resulted in 30 dB EMI reduction at 160kHz and in 15-20 dB for frequencies up to a few MHz, with significant benefits in terms of volume reduction of the input EMI filter compared to state-of-the-art techniques
A High Voltage Dc-Dc Converter for HEVs with a Novel Floating Control Stage
Get PDFHigh-side gate drivers to be used in EVs and HEVs should target high insulation voltage, as well as efficiency and monitoring capability. In traditional step-down converters, the entire control stage is referred to ground, thus either a pulse transformer or an isolated integrated gate driver is required. The paper proposes a buck converter having the entire control unit referred to the floating node. The design was carried out considering discrete components, which allows for low-cost and low-profile implementation. Simulations were conducted to validate the proposed converter, and to compare it with traditional high-side gate driver topologies. The overall efficiency results to be consistent with the other topologies, whereas the estimated occupied area and the cost, at PCB level, are both significantly lower
Real-Time Defect Detection of Wheel Bearing by Means of a Wirelessly Connected Micro- phone
No full textIn this work, an electronic system aiming to automatically
monitor the state of health of wheel bearings, is
proposed. The focus is on designing a low cost, small size and
wirelessly interfaced module. Acoustic emissions are exploited to
detect defects by means of a low cost micro electro-mechanical
system (MEMS) microphone. A microcontroller was used to
evaluate the frequency spectrum and to interface the system
through a wireless data link. The designed module successfully
achieved the proposed goals. Finally, a novel measurement
process is presented to evaluate the system performance under
realistic conditions
Metodo di trasmissione e ricezione di dati mediante trasmissione di segnali acustici in un fluido di una condotta, impianto e ricetrasmettitore per l’attuazione del detto metodo
No full text
A Low-Cost, Small-Size, and Bluetooth-Connected Module to Detect Faults in Rolling Bearings
Get PDFCondition 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 Critical Assessment of Open-Loop Active Gate Drivers Under Variable Operating Conditions
Get PDFActive gate drivers have been investigated in power circuits to reduce unwanted over-voltages and over-currents, whilst keeping the transients fast. Indeed, the use of such a kind of driver avoids the triggering of oscillations related to high frequency parasitic resonant circuits, which affect adversely the electro-magnetic interference delivered by power modules. However, in the case of fast power switches, the driver is working in an open-loop manner, and the modulation pattern is fixed. This paper assesses the effects of different operating conditions on the switching waveforms of an AGD-driven power transistor. More precisely, load current, input voltage and temperature variations were investigated on an open-loop active gate driver comprised in a Buck converter. Experimental results suggest that the AGD is no longer effective in damping the unwanted oscillations under a significant change of the operating conditions
Reduction of Common Mode Conducted EMI in GaN-Based Two-Switch Flyback Converters Using the Delay Compensation Technique
Get PDFCommon mode conducted EMI is a critical issue in power switching converters, particularly in automotive
applications. Symmetrical topologies like two-switch flyback are effective in reducing EMI, but the delay between high-side and
low-side switches can worsen the delivered EMI. This work investigates the use of the delay compensation technique in a
GaN-based two-switch flyback converter. The study addresses both impedance balancing and delay effects on conducted EMI.
Simulation results confirm a 25 dB reduction at 200 kHz with both delay compensation and impedance balancing compared to
a traditional flyback converter
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