1,720,965 research outputs found
Real-time temperature sensitive electrical parameters and model- based condition monitoring for PV inverter applications
No full textTo improve the reliability of power converters, condition monitoring is a useful approach as this allows
to schedule maintenance more carefully or even implement adaptive control. The current state of the
art is focused on the measurement of damage sensitive parameters which can be used directly or
complementary with a digital twin. Several papers report successful experiments where these damage
sensitive parameters of switching devices are used to evaluate wear under constant power conditions.
This approach needs to be extended for PV inverter applications as these experience complex power
profiles in varying weather conditions. This poster presentation will focus on a methodology to monitor
the damage sensitive drain to source on-resistance in concession with the internal gate resistance which
is only sensitive to the junction temperature. This allows to separate the influence of temperature and
damage which allows the use of complex mission profiles. To simplify the evaluation even further, a
second approach is proposed where the additional gate resistance measurement is replaced by a
modeling strategy. The electrical part of the electro-thermal model is build using a two dimensional
lookup table approach and the thermal model is represented by a Cauer network. The thermal
resistances in each layer are determined by a FEM simulation. This poster presents the preliminary
results which show a validation of the model with measurements on an inverter prototype and the
proposed condition monitoring circuits simulated in spice
Cost Comparison for Different PV-Battery System Architectures Including Power Converter Reliability
No full textThis paper compares the levelized energy cost of a commercial DC-coupled photovoltaic battery systems with a multiple input multiple output converter. The comparison is based on an electrothermal simulation allowing to include the actual converter efficiency and degradation in different use cases. The multiple input multiple output converter proofs to be less expensive and more reliable, however, the lower efficiency causes the final levelized energy cost to be higher.This work has been supported by Flanders Innovation & Entrepreneurship and Flux50 under project DAPPER, HBC.2020.2144. Martijn Deckers is funded by a PhD grant of the Research Foundation Flanders (FWO), 1S87522N
Cost Comparison for Different PV-Battery System Architectures Including Power Converter Reliability
No full textThis paper compares the levelized energy cost of a commercial DC-coupled photovoltaic battery systems with a multiple input multiple output converter. The comparison is based on an electrothermal simulation allowing to include the actual converter efficiency and degradation in different use cases. The multiple input multiple output converter proofs to be less expensive and more reliable, however, the lower efficiency causes the final levelized energy cost to be higher.This work has been supported by Flanders Innovation & Entrepreneurship and Flux50 under project DAPPER, HBC.2020.2144. Martijn Deckers is funded by a PhD grant of the Research Foundation Flanders (FWO), 1S87522N
Real-time temperature sensitive electrical parameters and model- based condition monitoring for PV inverter applications
No full textTo improve the reliability of power converters, condition monitoring is a useful approach as this allows
to schedule maintenance more carefully or even implement adaptive control. The current state of the
art is focused on the measurement of damage sensitive parameters which can be used directly or
complementary with a digital twin. Several papers report successful experiments where these damage
sensitive parameters of switching devices are used to evaluate wear under constant power conditions.
This approach needs to be extended for PV inverter applications as these experience complex power
profiles in varying weather conditions. This poster presentation will focus on a methodology to monitor
the damage sensitive drain to source on-resistance in concession with the internal gate resistance which
is only sensitive to the junction temperature. This allows to separate the influence of temperature and
damage which allows the use of complex mission profiles. To simplify the evaluation even further, a
second approach is proposed where the additional gate resistance measurement is replaced by a
modeling strategy. The electrical part of the electro-thermal model is build using a two dimensional
lookup table approach and the thermal model is represented by a Cauer network. The thermal
resistances in each layer are determined by a FEM simulation. This poster presents the preliminary
results which show a validation of the model with measurements on an inverter prototype and the
proposed condition monitoring circuits simulated in spice
Real-Time MOSFET Condition Monitoring for Variable Mission Profiles With a Dual Extended Kalman Filter
No full textThe article proposes a methodology to detect real-time power mosfet degradation, in variable mission profile applications, using externally measurable electrical parameters. This complements the work done for fixed operation conditions in current literature. To achieve this, the damage and temperature sensitive drain to source resistance is accompanied with a gate resistance measurement only sensitive to temperature. Together, they allow for the detection of, and the distinction between, bond wire and die attach solder layer degradation. A dual extended Kalman filter is used to filter the measurement data and to estimate the change in thermal model. The article shows the measurement circuits together with proof of concept lab results in a solar photovoltaic use case. The main aim is to show that the resistance measurement can be compensated for mission profile temperature variations and that the thermal resistance can be estimated, reflecting bond wire and die attach solder layer degradation.Flanders Innovation & Entrepreneurship and Flux50 under project DAPPE
Impact of Measurement Data Time Resolution on Predicted Lifetime of PV Inverters in Residential Solar Panel Systems
No full textThe reliability of grid-tied PV inverters without integrated battery is compared with AC/DC-coupled PV- battery systems while varying the time resolution of the load and mission profiles (1 min – 60 min). Adding a battery increases self-consumption and can lower the needed grid power capacity in both DC- and AC-coupled configurations. A comparison between a battery-free PV system and a grid-tied PV-battery system shows that adding a battery to the system will not only improve the energy performance of the system but also increase the lifetime of the inverter (~15% in DC-coupled structure). The results have been extracted for two cases: (a) varying both mission profile and load profile resolutions, (b) varying the available load profile time resolution while keeping the mission profile time resolution constant at 1 min. The obtained results show that in our case, the influence of mission profile time resolution is greater than the input of load data. However, the expected PV inverter lifetime does not differ much for different time resolutions. This can highlight the importance of using measurement data with a resolution of even less than 1 minute because higher IGBT junction temperature swings can happen in a few seconds which cannot be seen in lower time resolutions
Simulation-Based Investigation of Wind Turbine Induced Shadow Flicker on IGBT Reliability and Energy Yield in Solar Converters in Hybrid Wind-Solar Systems
No full textWith the growing adoption of renewable energy, hybrid wind-solar plants are gaining interest because they allow the increase of energy yield per unit of surface area. However, the presence of wind turbines creates unique shading scenarios for the solar panels. This work presents a simulation-based approach to investigate the solar plant's energy yield and converter IGBT lifetime in the presence of dynamic and fast-moving shadows created by the wind turbine blades. First, the need for a dynamic simulation as opposed to a static one is examined. Next, the sensitivity of Photovoltaic (PV) string orientation, PV string location, wind direction, Maximum Power Point Tracker (MPPT) control speed, and turbine rotor speeds on energy yield and IGBT lifetime are investigated in a case study. Results show that dynamic and static simulations can show vastly different results. MPPT can have difficulty with shadow flicker, resulting in different string voltages depending on the MPPT update speed and wind turbine rotor speed. The shadow flicker introduces additional temperature swings in the IGBT, but these are too small to add any significant lifetime consumption (<1.2%). Thus, the observed changes in lifetime consumption are caused mainly by controller behavior and static shadows. Finally, it is concluded that PV strings are better placed south, east, or west of the wind turbine for optimal energy yield and lifetime consumption. A northern placement can be suitable if there is a significant distance (+50 m) between the PV string and the wind turbine.This work was supported by the Belgian Energy Transition Funds/Met de steun van het Energietransitiefonds
A Real-time Physics Based Digital Twin for Online MOSFET Condition Monitoring in PV Converter Applications
No full textThis article proposes a fast, lightweight and physics-based digital twin to estimate the real-time junction, case and heat sink temperatures of the switching device in a photovoltaic (PV) boost converter. A lookup table approach is used to model the electric behavior while a traditional Cauer approach is used for the thermal model. To extract the thermal resistances of the MOSFET layers and convection, a finite element method (FEM) simulation is performed. To validate the digital twin, a physical replica of the boost converter is built and a real mission profile is applied. The resulting heat sink temperature profile has a mean average error of 0.8 °C with an increase in error at higher temperatures. In future work this twin will be used to separate the effect of temperature and degradation on the on resistance of the MOSFET to monitor degradation during operation.status: Published onlin
Practical Challenges of High-Power IGBT’s I-V Curve Measurement and Its Importance in Reliability Analysis
Full text linkThis paper examines the practical challenges of simplified setups aimed at achieving high-power IGBTs’ IC–VCE curve. The slope of this I–V curve (which is defined as on-resistance RCE) and the point where the VCE–VGE curve visibly bends (threshold gate voltage) can be suitable failure precursor parameters to determine an IGBT’s health condition. A simplified/affordable design for these specific measurements can be used for in-situ condition monitoring or field testing of switching devices. First, the possible I–V curve measurement methods are discussed in detail in order to prevent self-heating. The selected design includes two IGBTs in which the high-side IGBT was the device under test (DUT) with a constant gate voltage (VGE) of 15 V. Then, the low-side IGBT was switched by a short pulse (50 μs) to impose a high-current pulse on the DUT. The VCE–VGE curve was also extracted as an important failure-precursor indicator. In the next stage, a power-cycling test was performed, and the impact of degradation on the IGBT was analyzed by these measurement methods. The results show that after 18,000 thermal cycles, a visible shift in I–V curve can be seen. The internal resistance increased by 13%, while the initial collector-emitter voltage and voltage at the knee point in the VCE–VGE curve slightly changed. It is likely that in our case, during the performed power-cycling test and aging process, the bond wires were most affected, but this hypothesis needs further investigation
Semi-automated presurgical planning of maxillofacial reconstruction with fibula free flap: software development and evaluation
No full textWanneer de onderkaak lijdt aan tumoren, ziekten of een fysiek trauma is kaakreconstructie met de fibula-free flab een veelgebruikte methode om zowel de functionaliteit en vorm te herstellen. Momenteel gebeurt de prechirurgische planning van deze reconstructie handmatig aan het UZ Leuven. Omdat deze taak erg tijdrovend en vervelend kan zijn is een nieuwe planningssoftware met een semi-geautomatiseerde aanpak nodig. Deze thesis bespreekt het ontwerp en de structuur van de nieuwe software, die is geprogrammeerd in MeVisLab. De algemene benadering is de reconstructie opsplitsen in kleinere stappen, waarbij de software tools en suggesties aanbiedt om de gebruiker te helpen. De software ondersteunt reconstructies met één, twee en drie segmenten. Een double-barrel reconstructie is ook mogelijk. De evaluatie wordt uitgevoerd door een medisch expert van het UZ Leuven. Uit evaluatie blijkt dat de kwaliteit van de nieuwe software hoog genoeg is om reconstructies bij patiënten uit te voeren. Ook de stapsgewijze aanpak verlicht de ervaring voor gebruikers. Het gebruiksgemak is echter niet optimaal, de interface is soms druk en verwarrend. Toekomstig werk bestaat uit het toevoegen van nieuwe functies en het verbeteren van de bestaande functionaliteiten. De huidige software vormt een goed raamwerk voor toekomstige aanvullingen
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