L'abstract è  presente nell'allegato / the abstract is in the attachmen

QUITADAMO, MATTEO VINCENZO

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L'abstract è  presente nell'allegato / the abstract is in the attachmen

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08 November 2022POLITECNICO DI TORINORepository ISTITUZIONALEOptimal Tuning of AGDs Parameters and a Technique for Testing the Correct Mounting of Heatsinks on PowerTransistors / Quitadamo, MATTEO VINCENZO. - (2021 Dec 10), pp. 1-157.OriginalOptimal Tuning of AGDs Parameters and a Technique for Testing the Correct Mounting of Heatsinks onPower TransistorsPublisher:PublishedDOI:Terms of use:Altro tipo di accessoPublisher copyright(Article begins on next page)This article is made available under terms and conditions as specified in the  corresponding bibliographic description inthe repositoryAvailability:This version is available at: 11583/2957732 since: 2022-03-09T10:22:05ZPolitecnico di TorinoOptimal Tuning of AGDs Parameters and aTechnique for Testing the Correct Mounting ofHeatsinks on Power TransistorsCandidate: Matteo Vincenzo QuitadamoSupervisor: Prof. Franco FioriNovember 2021Nowadays, energy conversion is one of the most popular topics addressed bothin research and industrial environment. The reason for that is, in the last decadesthe energy consumption related to carbon fossil combustion has caused several neg-ative effects on the environment, such as the global warming and the increase of thepollution level, leading the humanity to spend time and resources for increasing theutilization of energy sources with a low impact on the ambient, like the photovoltaicand the wind generated ones. Nevertheless such forms of energy are ”green”, theyneed to be converted and delivered in order to be exploited in the best way. Suchsubject has brought the Power Converters and all the related topics, and componentswhich make up the power module to become a burning issue of the last years. Whenspeaking about the conversion of the energy, the designer has to deal with severalissues, among which the efficiency and thermal management of the system, whichare two of the most critical aspects of the design flow, both mainly related to themost important components of a power converter, the power switches. These com-ponents are continuously under investigation, in order to improve their performancein terms of voltage and current handling, switching speed and power losses, leadingthe Silicon device to approach very close their theoretical limits. For such a reason,new semiconductor materials, the Wind Band-Gap (WBG), have been investigatedto develop even more performant power switches, with the aim of replacing theirSilicon counterpart. Such devices, with their faster switching transients and smallerparasitic capacitances, can excite high frequency resonant circuits occurring in oscil-lations, overvoltages and/or overcurrents that could destroy the power transistor andincrease the level of the Electromagnetic Interference (EMI). Traditional approachesto solve such an issues consist of using snubber circuits and/or to reduce the strengthof the driver increasing the gate resistance. Nevertheless such solutions remove theoscillations, reducing the overvoltages and the overcurrents, they can reduce exces-sively the switching speed of the transient, increasing the switching losses and so1the temperature of the switches, which need of even larger heatsinks to dissipate theproduced heat and making ineffective the use of WBG devices. A consolidate solu-tion to fix such issues consists of using Active Gate Driver (AGD) to turn-on and toturn-off the power switches. Such solution allows the designer to control the switch-ing waveforms during the transitions, by modulating the strength of the driver andproviding the user the capability to find the best trade-off between the power lossesand the switching speed. Notwithstanding the effectiveness of the AGD techniques,it worth highlighting that in literature any method to derive the gate driving profileis provided, and the driving waveforms is often obtained by means of trial and errorapproach.The aim of the first part of this thesis is to fill such gap, by providing a mathe-matical model to obtain the optimal switching waveforms, i.e, the non oscillating andless dissipative ones is proposed, and then an algorithm to obtain the optimal gatecurrent profile by means of simulation is proposed. The optimal switching waveforms,along with the parameters resulting from the proposed algorithm, are a step forwardwith respect to the trial-and-error or local optimization methods that can be foundin literature. Indeed, the proposed approach provides the target output waveforms,thus knowing in advance the best trade-off between power dissipation and switchingspeed. The method discussed in this work is then applied on a prototype, resultingin the optimal switching waveforms expected from the proposed analysis.In the second part of this thesis, the focus moves on the thermal management ofpower transistors, more precisely on the capability of a power MOSFET, on which ismounted an heatsink, to dissipate the heat. In particular, two end of manufacturytest strategies to check the correct assembling of an heatsink on the power switchare proposed. Such techniques are based on the linear relationship existing betweenthe drain source on resistance (Rds,on) and the junction temperature Tj, so theydo not requires any temperature measurements, once the calibration procedure isperformed. The former technique can be applied to transistors which gate can bereached with an Automatic Test Equipment (ATE) controlling the duration of the onphase of the device, the latter can be applied on power transistors mounted in hardswitching power converter, while they are normally working. The proposed techniqueare both experimental assessed considering several commercial heatsinks and differentinduced thermal faults, which simulate the incorrect behavior of the heatsink. Theexperimental validation has allowed for the identification the thermal faults in morethan 90% of the analyzed cases.2

Optimal Tuning of AGDs Parameters and a Technique for Testing the Correct Mounting of Heatsinks on Power Transistors

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Optimal Tuning of AGDs Parameters and a Technique for Testing the Correct Mounting of Heatsinks on Power Transistors

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