5.7 Gradient heat flux sensor
5.7.1 Experiment
The GHFS has been tested with the circuit shown in Figure 5.20. Two IGBT modules T1
and T2 operated in a complimentary manner are placed on the heat sink as shown in Figure 5.21, and a fan (the flow rate is 2.6 m3/min) is installed on one end of the aluminium heat sink. The dimensions of the heat sink base are 180 × 125 mm and the height is 120 mm.
The dimensions of the fan are 120 × 120 × 38 mm. The IGBT module shown in Figure 2.16 is used, and the characteristics of the module are listed in Table 5.1 and Table A.2 of Appendix A. The signals for the opening and closing of the IGBTs are generated by carrier-based PWM; the unidirectional carrier sine wave frequency is 0.05 Hz and the unidirectional triangular wave frequency is 1 kHz. The GHFS is installed between the baseplate of T2 and the heat sink as presented in Figure 5.22, and the thermocouple is placed close to the GHFS to measure case temperature.
Figure 5.20. Schematic of the circuit used for the experiment.
GHFS, thermocouple RL
4,1 mF
Shunt 250A 150 mV
0.7 Ohm
Us T1 T2
I
Figure 5.21. Photograph of the test set-up.
Figure 5.22. Photograph of the GHFS and the thermocouple installed on the baseplate of IGBT module T2.
The heat flux measured by the GHFS and the case temperature measured by the thermocouple in the experiment are shown in Figure 5.23, where Us is changed from 12
Thermal modelling and reliability analysis of IGBT modules 108
V to 22 V at 1980 s, and the current of the circuit I is from 15 A to 30 A. The heat flux and the case temperature in the steady-state are shown in Figure 5.24 (Us is 12 V). The average heat flux in the steady state is measured to be 1070 W/m2 whenUs = 12 V andI
= 15 A and 2020 W/m2 whenUs = 22 V andI = 30 A. The area of the baseplate of the IGBT module is 0.0604 × 0.1064 m2. Thus, assuming that the heat flux is uniform, the losses measured atUs = 12 V are 6.9 W and atUs = 22 V are 13.0 W. The losses estimated based on electrical parameters equal 6.6 W and 12.9 W, respectively. The difference between the measured and estimated results can be explained by the fact that the heat flux is not uniform and has a higher value under the chip area.
Figure 5.23. Heat flux and case temperature measured in the experiment.Us is changed from 12 V to 22 V at 1980 s.
0 500 1000 1500 2000 2500 3000 3500 4000
0 1000 2000 3000
Time (s) Heatflux(W/m2 )
20 25 30 35 40 45 50
Casetemperature(DegreeCelsius)
Figure 5.24. Heat flux and case temperature measured from 1800 to 1900 s (Us is 12 V). The waveforms measured in this experiment are also shown in Figure 5.23.
The simple tests shown here demonstrate the opportunity to implement the proposed cooling control for the most efficient cooling cases; one might assume that this kind of a controlled cooling technology may become commercially available in the future.
5.8
SummaryAn analysis of the effects of cooling on the estimated lifetime of an IGBT switch was carried out. It was shown that in the case of a very efficient and low time constant cooling, the power electronic switch may suffer from a significant lifetime reduction as the temperature cycling becomes excessive compared with a high-inertia cooling. In the case of a very efficient low time constant cooling, the situation may be improved by arranging control in the cooling. Controlled cooling needs a feedback signal from the heat flux of the switch. A GHFS may be used as such as a feedback element as it reacts fast to the changes in the heat flux.
In this case, the GHFS was used in quite an inefficient way. However, in the future, integrating such a sensor close to the power chip could make the controlled cooling even more efficient in reducing the thermal cycling stresses of an IGBT in cyclic loads such as wind power.
1800 1810 1820 1830 1840 1850 1860 1870 1880 1890 1900 1000
1050 1100 1150
Time (s) Heatflux(W/m2 )
1800 1810 1820 1830 1840 1850 1860 1870 1880 1890 1900 25.85
25.9 25.95
26 26.05
Time (s)
Casetemperature(°C)
6 Conclusions
This doctoral dissertation presents a study on the design of the power converter main circuit. The main purpose was to develop methods and tools for the design of the converter with a high power density and reliability.
In this study, models to evaluate electromagnetic and thermal performances of the multilevel converter were developed. This work provides guidelines on the design process of the laminated busbar system with a minimized stray inductance of the converter commutation loops. The electromagnetic model of the converter busbar system and the IGBT modules was established to estimate the stray inductance and analyse the electromagnetic coupling between the converter components. A low-inductive busbar system for the three-level ANPC converter was introduced where the symmetrical arrangement of the components is applied to obtain equal stray inductance values in the three phases. The results of the induction estimation were validated by measurements. A circular layout of the busbar system was proposed in order to obtain an equal current sharing between the parallel-connected devices and implemented in the NDT set-up.
In addition to the electromagnetic analysis, the method of a comprehensive thermal analysis of the busbar system was introduced to ensure that the critical temperatures are not exceeded in the designed busbar system. The thermal analysis is based on the 3D LPTM covering all heat transfer mechanisms: conduction, convection, and radiation. The temperature-dependent thermal and electrical parameters of the busbar system materials and of the cooling medium are used to calculate the temperature-dependent Joule losses and thermal resistances of the LPTM. An iterative procedure is implemented for the power losses and the temperature estimation. The main sources of heat in the busbar system are found to be the Joule losses resulting from the contact resistances and the resistances of the IGBT module main terminals. In order to improve the thermal performance of the busbar system, a low contact resistance has to be ensured; this can be achieved, for example, by gold plating of the contact surfaces. The suitability of the thermal model is verified experimentally and by FEM simulations.
With the aim of investigating the effect of the cooling solution on the reliability of the IGBT module in applications with varying loads (e.g. wind turbines), a lifetime estimation algorithm was provided. The lifetime of the IGBT was estimated based on the mission profile of the converter for the South Karelia wind speed distribution. The results of the analysis showed that the thermal inertia of the cooling solution has a significant influence on the reliability of the IGBT module. Thus, in order to select a cooling solution for a specific application that allows achieving a high power capability and the required reliability, the lifetime prediction should be performed at the design stage. The cooling solutions that have a high thermal inertia and maintain a constant heat sink temperature at varying loads are preferred to decrease the thermal cycling stress of the IGBT and thereby improve reliability. In this work, a method was proposed to control the heat sink temperature of the liquid cold plate as a simple way to extend the IGBT lifetime. The method is based on the use of the GHFS to measure the heat flux, and the liquid flow rate
Conclusions 112
is adjusted based on the measured heat flux to maintain a constant heat sink temperature.
The simulation results show an improvement in the lifetime. Further work should be concentrated on the implementation of the control method in the prototype. The investigation of the option to place the GHFS inside the IGBT module is required as this can further lower the thermal cycling stress of the IGBT.
Furthermore, a complex optimization methodology that incorporates the design methods proposed in this doctoral dissertation has to be developed in order to optimize the converter performance for instance in terms of power density, reliability, and cost.
References
ABB (2012). ABB Application note 5SYA 2093-00: "Thermal design and temperature ratings of the IGBT modules." [Online]. [Retrieved 8 April 2015]. Available at:
http://www05.abb.com.
ABB (2014). Application note 5SYA 2039-06: "Mounting instructions for HiPak modules." [Online]. [Retrieved 8 April 2015]. Available at:http://www05.abb.com/.
Abbate, C., Busatto, G., and Iannuzzo, F. (2010). "IGBT RBSOA non-destructive testing methods: Analysis and discussion."Microelectronics Reliability, 50(9-11), pp. 1731–
1737.
Alexandrova, Y., Semken, R.S., and Pyrhönen, J. (2014). "Permanent magnet synchronous generator design solution for large direct-drive wind turbines: Thermal behavior of the LC DD-PMSG."Applied Thermal Engineering, 65(1-2), pp. 554–563.
Alt n, M., et al. (2010). "Overview of recent grid codes for wind power integration." In 12th International Conference on Optimization of Electrical and ElectronicEquipment (OPTIM), pp. 1152–1160.
Ardon, V., et al. (2010). "EMC modeling of an industrial variable speed drive with an adapted PEEC method."IEEE Transactions on Magnetics, 46(8), pp. 2892–2898.
Askeland, D.R. and Haddleton, F. (1996).The Science and Engineering of Materials, 3rd edn. London and Melbourne: Chapman & Hall.
Bagnoli, P.E., Casarosa, C.E., Ciampi, M., and Dallago, E. (1998). "Thermal resistance analysis by induced transient (TRAIT) method for power electronic devices thermal characterization. I. Fundamentals and theory." IEEE Transactions on Power Electronics, 13(6), pp. 1208–1219.
Baker, R.H. (1980).High-voltage converter circuit. U.S. Patent 4 203 151, May 13, 1980.
Barnes, C.M. and Tuma, P.E. (2010). "Practical Considerations Relating to Immersion Cooling of Power Electronics in Traction Systems." IEEE Transactions on Power Electronics, 25(9), pp. 2478–2485.
Bedkowski, M., et al. (2014). "Coupled numerical modelling of power loss generation in busbar system of low-voltage switchgear."International Journal of Thermal Sciences, 82, pp. 122–129.
Bellar, M.D., et al. (1998). "A review of soft-switched DC-AC converters." IEEE Transactions on Industry Applications, 34(4), pp. 847–860.
References 114
Bernet, S., et al. (2003). "Design, test and characteristics of 10 kV IGCTs." In 38th IAS Annual Meeting, Conference Record of the Industry Applications Conference, 2, pp.
1012–1019.
Bhunia, A., Chandrasekaran, S., and Chung-Lung, C. (2007). "Performance Improvement of a Power Conversion Module by Liquid Micro-Jet Impingement Cooling." IEEE Transactions on Components and Packaging Technologies, 30(2), pp. 309–316.
Blaabjerg, F., Jaeger, U., Munk-Nielsen, S., and Pedersen, J. (1995). “Power Losses in PWM-VSI Inverter Using NPT and PT IGBT Devices."IEEE Transactions on Power Electronics, 10(3), pp. 358–367.
Bose, B.K. (2013). "Global Energy Scenario and Impact of Power Electronics in 21st Century."IEEE Transactions on Industrial Electronics, 60(7), pp. 2638–2651.
Braunovic, M. (2002). "Effect of connection design on the contact resistance of high power overlapping bolted joints."IEEE Transactions on Components and Packaging Technologies, 25(4), pp. 642–650.
Bruckner, T. (2005). "The Active NPC Converter for Medium-Voltage Drives.". Ph.D.
dissertation. Fakultät Elektrotechnik und Informationstechnik der Technischen Universität Dresden.
Bruckner, T. and Bemet, S. (2001). "Loss balancing in three-level voltage source inverters applying active NPC switches." InIEEE 32nd Annual Power Electronics Specialists Conference PESC, 2, pp. 1135–1140.
Bryant, A.T., Parker-Allotey, N., and Palmer, P.R. (2007). "The Use of Condition Maps in the Design and Testing of Power Electronic Circuits and Devices." IEEE Transactions on Industry Applications, 43(4), pp. 902–910.
Busatto, G., Abbate, C., Abbate, B., and Iannuzzo, F. (2008). "IGBT modules robustness during turn-off commutation. "Microelectronics Reliability, 48(8–9), pp. 1435–1439.
Busatto, G., Abbate, C., Iannuzzo, F., and Cristofaro, P. (2009). "Instable mechanisms during unclamped operation of high power IGBT modules." Microelectronics Reliability, 49(9–11), pp. 1363–1369.
Busca, C., et al. (2011). "An overview of the reliability prediction related aspects of high power IGBTs in wind power applications."Microelectronics Reliability, 51(9-11), pp.
1903–1907.
Caponet, M., Profumo, F., De Doncker, R., and Tenconi, A. (2002). "Low stray inductance bus bar design and construction for good EMC performance in power electronic circuits."IEEE Transactions On Power Electronics, 17(2), pp. 225–231.
Ciappa, M. (2001). Some reliability aspects of IGBT modules for high-power applications. ETH Zurich: Ph.D. thesis.
Clavel, E., Roudet, J., Chevalier, T., and Postari, D.M. (2009). "Modeling of connections taking into account return plane: Application to EMI modeling for railway." IEEE Transactions on Industrial Electronics, 56(3), pp. 678–684.
Coneybeer, R.T., Black, W.Z., and Bush, R.A. (1994). "Steady-state and transient ampacity of bus bar."IEEE Transactions on Power Delivery, 9(4), pp. 1822–1829.
Dickerson, J.A. and Ottaway, G.H. (1971).Transformeless power supply with line to load isolation. U.S. Patent 3 596 369, Aug. 1971.
Du Pont Films (2014a). Product information: "Kapton Polyamide Film." [Online].
[Retrieved 8 April 2015]. Available at:http://www2.dupont.com/.
Du Pont Films (2014b). Product information: "Teflon FEP Fluorocarbon Film." [Online].
[Retrieved 8 April 2015]. Available at:http://www2.dupont.com/.
Du Pont Teijin Films (2014). Product Information: "Mylar Polyester Film (Electrical Properties)." [Online]. [Retrieved 8 April 2015]. Available at:
http://usa.dupontteijinfilms.com/.
US Department of Energy Facilities (2014). Progress Report: "Advancing Solar Energy Across America." [Online]. [Retrieved 8 April 2015]. Available at:
http://www.energy.gov/.
Filsecker, F., Alvarez, R., and Bernet, S. (2013). "Comparison of 4.5-kV Press-Pack IGBTs and IGCTs for Medium-Voltage Converters."IEEE Transactions on Industrial Electronics, 60(2), pp. 440–449.
Franquelo, L.G., et al. (2008). "The age of multilevel converters arrives."IEEE Industrial Electronics Magazine, 2(2), pp. 28–39.
Frisch, M. and Ernö, T. (2010). "Power module with additional low inductive current path." In: 6th International Conference on Integrated Power Electronics Systems (CIPS), pp. 1–6.
Gamry Instruments (2012). Operator's Manual: "Gamry Instruments Potentiostat/Galvanostat/Zero Resistance Ammeter." [Online]. [Retrieved 8 April 2015]. Available at:http://www.gamry.com.
Grobler, I. and Gitau, .M.N. (2013). "Characterising and modelling extended conducted electromagnetic interference in densely packed DC-DC converter." In 2013 IEEE Energy Conversion Congress and Exposition (ECCE), pp. 1676–1681.
References 116
Grover, F.W. (1946).Inductance Calculations. New York: D. Van Nostrand Company.
Hallam, C.R.A. and Contreras, C. (2015). "Evaluation of the Levelized Cost of Energy Method for Analyzing Renewable Energy Systems: A Case Study of System Equivalency Crossover Points Under Varying Analysis Assumptions."IEEE Systems Journal, 9(1), pp. 199–208.
Heldwein, M.L. and Kolar, J.W. (2009). "Impact of EMC Filters on the Power Density of Modern Three-Phase PWM Converters."IEEE Transactions on Power Electronics, 24(6), pp. 1577–1588.
Hey, J., Howey, D.A., Martinez-Botas, R., and Lamperth, M. (2011). "Transient thermal modelling of an Axial Flux Permanent Magnet (AFPM) machine with model parameter optimisation using a Monte Carlo method." In Vehicle Thermal Management Systems VTMS 10.
Hoer, C. and Love, C. (1965). "Exact inductance equations for rectangular conductors with applications to more complicated geometries." Journal of Research of the National Bureau of Standards. Section C: Engineering and Instrumentation, 69C(2), pp. 127–137.
Holloway, C.L., Kuester, E.F., Ruehli, A.E., and Antonini, G. (2013). "Partial and Internal Inductance: Two of Clayton R. Paul’s Many Passions."IEEE Transactions on Electromagnetic Compatibility, 55(4), pp. 600–613.
Hua, G. and Lee, F.C. (1995). "Soft-switching techniques in PWM converters." IEEE Transactions on Industrial Electronics, 42(6), pp. 595–603.
Hus, J. (1990). "Estimating busbar temperatures." IEEE Transactions on Industry Applications, 26(5), pp. 926–934.
Hwang, C.-C., Chang, J.J., and Jiang, Y.H. (1998). "Analysis of electromagnetic and thermal fields for a bus duct system."Electric Power Systems Research, 45(1), pp. 39–
45.
IEEE (1994).IEEE Recommended Practice for Electric Power Distribution for Industrial Plants. IEEE Std 141-1993, pp. 1–768.
IEEE (2010). IEEE Standard Framework for Reliability Prediction of Hardware. IEEE Std 1413-2010 (Revision of IEEE Std 1413-1998), pp. 1–20.
Incropera, F.P. (2006). Fundamentals of Heat and Mass Transfer. Hoboken, NJ: John Wiley & Sons.
Infineon (2010). Application note: "Technical information IGBT modules, Use of power cycling curves for IGBT4." [Online]. [Retrieved 8 April 2015]. Available at:
https://www.infineon.com/.
Infineon (2013). "AN2012-05 - 62mm Modules Application and assembly notes."
[Online]. [Retrieved 8 April 2015]. Available at:http://www.infineon.com.
International Energy Agency (2013). "Key World Energy Statistics." [Online.] [Retrieved 8 April 2015]. Available at:http://www.iea.org/.
Ivanova, M., et al. (2006). "Heat Pipe Integrated in Direct Bonded Copper (DBC) Technology for Cooling of Power Electronics Packaging." IEEE Transactions on Power Electronics, 21(6), pp. 1541–1547.
Jeng-Yue, C., et al. (2010). "LCOE reduction for megawatts PV system using efficient 500 kW transformerless inverter." In 2010 IEEE Energy Conversion Congress and Exposition (ECCE), pp. 392–397.
Ji, B., et al. (2015). "Multiobjective Design Optimization of IGBT Power Modules Considering Power Cycling and Thermal Cycling." IEEE Transactions on Power Electronics, 30(5), pp. 2493–2504.
Jussila, H.K., et al. (2013). "Local Heat Flux Measurement in a Permanent Magnet Motor at No Load."IEEE Transactions on Industrial Electronics, 60(11), pp. 4852–4860.
Kassakian, J.G. and Jahns, T.M. (2013). "Evolving and emerging applications of power eelectronics in systems." IEEE Journal of Emerging and Selected Topics in Power Electronics, 1(2), pp. 47–58.
Kaufmann, S. and Zwick, F. (2002). "10 kV IGBT press pack modules with series connected chips." In Proceedings of the 14th International Symposium on Power Semiconductor Devices and ICs, pp. 89–92.
Kerekes, T., et al. (2013). "An Optimization Method for Designing Large PV Plants."
IEEE Journal of Photovoltaics, 3(2), pp. 814–822.
Koktsinskaya, E.M., Roshal, A.G., and Karpishin, V.M. (2014). "Aging Tests of the High Current Aluminum–Copper Contact Connections in the ITER DC Busbar System."
IEEE Transactions on Plasma Science, 42(3), pp. 443–448.
Kouro, S., et al. (2010). "Recent Advances and Industrial Applications of Multilevel Converters."IEEE Transactions on Industrial Electronics, 57(8), pp. 2553–2580.
Koutroulis, E. and Blaabjerg, F. (2012). "Methodology for the optimal design of transformerless grid-connected PV inverters."IET Power Electronics, 5(8), pp. 1491–
1499.
References 118
Kroposki, B., et al. (2010). "Benefits of Power Electronic Interfaces for Distributed Energy Systems."IEEE Transactions on Energy Conversion, 25(3), pp. 901–908.
Lachassagne, L., Bertin, Y., Ayel, V., and Romestant, C. (2013). "Steady-state modeling of Capillary Pumped Loop in gravity field." International Journal of Thermal Sciences, 64, pp. 62–80.
Lai, J.-S., et al. (2006). "Inverter EMI modeling and simulation methodologies." IEEE Transactions on Industrial Electronics, 53(3), pp. 736–744.
Leong, C.-K. and Chung, D.D.L. (2004). "Pressure electrical contact improved by carbon black paste."Journal of Electronic Materials, 33(3), pp. 203–206.
Leon, J.I., et al. (2010). "Conventional Space-Vector Modulation Techniques Versus the Single-Phase Modulator for Multilevel Converters." IEEE Transactions Industrial Electronics, 57(7), pp. 2473–2482.
Li, S., Tolbert, L.M., Wang, F., and Zheng Peng, F. (2011). "P-cell and N-cell based IGBT module: Layout design, parasitic extraction, and experimental verification. " In Twenty-Sixth Annual IEEE Applied Power Electronics Conference and Exposition (APEC), pp. 372–378.
Ma, K., Blaabjerg, F., and Liserre, M. (2013). "Electro-thermal model of power semoconductors dedicated for both case and junction temperature estimation. " In Proceedings of PCIM Europe 2013, p. 1042–1046.
Ma, K. and Blaabjerg, F. (2012). "The Impact of Power Switching Devices on the Thermal Performance of a 10 MW Wind Power NPC Converter."Energies, 5(7), pp.
2559–2577.
Ma, K., Liserre, M., Blaabjerg, F., and Kerekes, T. (2015). "Thermal Loading and Lifetime Estimation for Power Device Considering Mission Profiles in Wind Power Converter."IEEE Transactions on Power Electronics, 30(2), pp. 590–602.
Mainka, K., Thoben, M., and Schilling, O. (2011). "Lifetime calculation for power modules, application and theory of models and counting methods. " InProceedings of the 2011- 14th European Conference on Power Electronics and Applications (EPE 2011), pp. 1–8.
Marquardt, R. (2002). Current Rectification Circuit for Voltage Source Inverters with Separate Energy Stores Replaces Phase Blocks with Energy Storing Capacitors.
German Patent (DE10103031A1), vol. 25.
McMurray, W. (1971). Fast response stepped-wave switching power converter circuit.
U.S. Patent 3 581 212.
Meynard , T.A. and Foch, H. (1992). "Multi-level conversion: high voltage choppers and voltage-source inverters." In: 23rd Annual IEEE Power Electronics Specialists Conference (PESC '92), 1, pp. 397–403.
Meysenc, L., Jylhäkallio, M., and Barbosa, P. (2005). "Power electronics cooling effectiveness versus thermal inertia."IEEE Transactions on Power Electronics, 20(3), pp. 687–693.
Millan, J., et al. (2014). "A Survey of Wide Bandgap Power Semiconductor Devices."
IEEE Transactions on Power Electronics, 29(5), pp. 2155–2163.
Miner, M.A. (1945). "Cumulative damage in fatigue."Journal of Applied Mechanics, pp.
A159–A164.
Mityakov, A.V., et al. (2012). "Gradient heat flux sensors for high temperature environments."Sensors and Actuators, A: Physical, 176, pp. 1–9.
Moreno, G., Jeffers, J.R., Narumanchi, S., and Bennion, K. (2014). "Passive two-phase cooling for automotive power electronics." In 30th Annual Semiconductor Thermal Measurement and Management Symposium (SEMI-THERM), pp. 58–65.
Morozumi, A., et al. (2013). "Direct liquid cooling module with high reliability solder joining technology for automotive applications." In25th International Symposium on Power Semiconductor Devices and ICs (ISPSD), pp. 109–112.
Munteanu , I., Bratcu , A.I., and Cutululis , N.-A. (2008).Optimal Control of Wind Energy Systems. Towards a Global Approach. London: Springer. 129 p.
Murashko, K.A., et al. (2014). "Thermal parameters determination of battery cells by local heat flux measurements."Journal of Power Sources, 271(20), pp. 48–54.
Musznicki, P., Schanen, J.-L., and Chrzan, P.J. (2003). "Design of high voltage busbar:
trade off between electrical field and stray inductance." In Proc. 3th International Workshop Compatibility in Power Electronics CPE. Gdansk.
Nerg, J., Rilla, M., and Pyrhönen, J. (2008). "Thermal analysis of radial-flux electrical machines with a high power density."IEEE Transactions on Industrial Electronics, 55(10), pp. 3543–3554.
Nieslony, A. (2009). "Determination of fragments of multiaxial service loading strongly influencing the fatigue of machine components." Mechanical Systems and Signal Processing, 23(8), pp. 2712–2721.
Ohkami, T., et al. (2007). "Development of a 40kV Series-connected IGBT Switch." In PCC '07 Power Conversion Conference - Nagoya, pp. 1175–1180.
References 120
Paul, C.R. (2010). Inductance: Loop and Partial, 1st edn. Hoboken, NJ: Wiley-IEEE Press.
Plecs (2014). "User manual of PLECS blockset version 3.6." [Online]. [Retrieved 8 April 2015]. Available at:http://plexim.com.
Plesca, A. (2012). "Busbar heating during transient conditions." Electric Power Systems Research, 89, pp. 31–37.
Popa, I.C., Dolan, A.-I., Ghindeanu, D., and Boltasu, C. (2014). "Thermal modeling and experimental validation of an encapsulated busbars system." In 2014 18th International Symposium on Electrical Apparatus and Technologies (SIELA), pp. 1–
4.
Popova, L., et al. (2013). "Stray inductance estimation with detailed model of IGBT module." In15th European Conference on Power Electronics and Applications (EPE), pp. 1–8.
Popova, L., et al. (2012). "Modelling of low inductive busbars for medium voltage three-level NPC inverter." InIEEE Power Electronics and Machines in Wind Applications (PEMWA), pp. 1–7.
Popova, L., et al. (2014). "Design and modeling of low-inductive busbars for a three-level
Popova, L., et al. (2014). "Design and modeling of low-inductive busbars for a three-level