Papers
2012 4th Electronic System-Integration Technology Conference, 2012
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The paper presents the feasibility of using gate-emitter voltage during IGBT turn-off in estimati... more The paper presents the feasibility of using gate-emitter voltage during IGBT turn-off in estimating the junction temperature of semiconductor chips in IGBT modules in real-time application. It is shown that the chosen parameter has negligible module and measurement circuit variation once benchmarked and has been implemented successfully in a converter.
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2012 7th International Conference on Integrated Power Electronics Systems, Mar 6, 2012
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The reliability of press-fit connectors of IGBT modules was investigated. No change in contact re... more The reliability of press-fit connectors of IGBT modules was investigated. No change in contact resistance between press-fit pins and PCB vias was found after active thermal cycling, vibration and corrosion, similar to [1,2]. However, the press-out forces after active thermal cycling have been reduced by ∼30%. In addition to chemical tin, also the cheaper Hot Air Levelling (HAL) was used as PCB finish and similar results have been shown. Furthermore, the current-carrying capability (also termed ampacity) of the press-fit pins was tested applying nominal current and two times nominal current. Again, no difference in electrical contact resistance before and after the test was found. Cases where one of the two pin legs was without contact to the via were also investigated by this method. It was shown that these partially open contacts are not influencing the current carrier capability significantly. Additional to the measurements, three dimensional finite element modelling (FEM) was emp...
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Long term reliability is a key requirement for IGBT modules. Besides wire bond degradation solder... more Long term reliability is a key requirement for IGBT modules. Besides wire bond degradation solder degradation is a main mechanism leading to IGBT module failures. A numerical model was developed to describe the solder degradation process. The model includes elastic and (time independent) plastic deformation, as well as primary and secondary creep. To verify the model it was successfully applied to different temperature cycle experiments with SnPb solder as well as SnAgCu solder. It was found that primary creep cannot be neglected for SnAgCu solders.
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This paper presents a method to implement reliability predictions at an early stage in the design... more This paper presents a method to implement reliability predictions at an early stage in the design process of power electronic equipment. Detailed information on the component losses are generated using circuit simulation tools. This loss map is applied in 3D thermal simulations of first layout proposals. With the resulting temperature distribution, a reliability prediction can be performed to identify critical components. This approach is studied with a 2.2 kW voltage source converter as example. The converter is cooled by natural convection only. Here, the DC link capacitors prove to be critical for the system lifetime. A simple geometric rearrangement of the capacitors already leads to a 60% increase in L10 lifetime, however at the cost of a decreased power density.
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In this paper, the reliability prediction of a power electronics building block (PEBB) printed ci... more In this paper, the reliability prediction of a power electronics building block (PEBB) printed circuit board assembly (PCBA) is performed using the Part Stress Method from the MIL-HDBK-217FN2 handbook. The breakdown of the predicted reliability with respect to circuit functional blocks is presented. Furthermore, different cases are shown, where the components with small or large failure rate dominate. Finally, the ANSI-VITA51.1 adjustments are applied and their influence on the reliability prediction results and their usage are discussed.
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In order to fully exploit the benefits of modular converters, dedicated hard- and software integr... more In order to fully exploit the benefits of modular converters, dedicated hard- and software integration technologies have been developed to complement modular multi-level circuit topologies. The technologies investigated include a wireless auxiliary power supply, a two-phase cooling, solid insulation, wireless optical communication, redundant EtherCAT networking and advanced IGBT junction temperature diagnostics. Emphasis was set on three key aspects of modularity: scalabilty, configurability and pluggability. To validate the technologies and to demonstrate their benefits, a medium voltage concept converter was built and operated. The combination of these technologies finally also enabled a'hot swap' functionality, where power modules can be replaced during converter operation. Hot swap has successfully been tested for a DC-link voltage of 3.3 kV and output power of 550 W.
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2010 IEEE 26-th Convention of Electrical and Electronics Engineers in Israel, 2010
ABSTRACT Many voltage source converters have no redundant power components (e.g. IGBT modules) bu... more ABSTRACT Many voltage source converters have no redundant power components (e.g. IGBT modules) built in. Therefore if one power component fails, the converter stops working. Here we introduce a generic approach that takes advantage of the inherent redundancies of voltage vectors in multilevel converters in order to actively extend the lifetime of converters. When detecting increased stress of one IGBT module, the switching strategy is altered in order to reduce the load of that particular IGBT module. The active lifetime extension (ALE) switching strategy aims to balance the remaining life of all IGBT modules at all times. In such way the lifetime of the converter is maximized.
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2011 Proceedings - Annual Reliability and Maintainability Symposium, 2011
ABSTRACT In order to improve sustainability of industrial applications, big efforts are underway ... more ABSTRACT In order to improve sustainability of industrial applications, big efforts are underway to increase efficiency of electrical power transmission, power conversion, or power usage. The availability of electrical converters used in these applications is crucial for high efficiency. Therefore, risk assessment has to be performed during product development to improve their reliability. The method typically used is Failure Mode and Effects Analysis (FMEA). In this paper another method called Design Review Based on Failure Mode (DRBFM) is applied to a typical power converter and evaluated. The DRBFM approach used was found to be much more efficient, if the focus lies on the identification of the critical problems and on improvements. On the other hand, FMEA is the method of choice for focusing on a complete list of possible failures.
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2013 IEEE ECCE Asia Downunder, 2013
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7th IET International Conference on Power Electronics, Machines and Drives (PEMD 2014), 2014
ABSTRACT The paper presents methods for the online estimation of the junction temperature (Tj) fo... more ABSTRACT The paper presents methods for the online estimation of the junction temperature (Tj) for IGBT modules with paralleled semiconductor chips, with each chip operating at different junction temperatures. Experimental and simulation results are presented. The Tj estimated from the gate-emitter voltage (Vge) during the IGBT switch off process was found to be very close to the average junction temperature of all the semiconductor chips in the IGBT module. The Tj estimated from the dVce/dt slope at lower voltages was found to represent the highest temperature of all the semiconductor chips in the IGBT module.
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GaN-based Electronic Devices, Raman Spectroscopy
We report our recent progress in developing technol-ogy to probe the temperature of electronic de... more We report our recent progress in developing technol-ogy to probe the temperature of electronic devices, illus-trated for GaN and GaAs-based HEMTs with high time and sub-micron spatial resolution, demonstrating a tem-poral resolution as short as 10 ns. Understanding tran-sient heating in pulsed-operated HEMTs is important in order to optimize device performance and reliability. It is also important to assess the validity of electrical testing methods. Quasi-adiabatic heating in GaN based devices is identified within the first ~70 ns of device operation, and we find that the temperature reaches as high as 25% of the DC temperature when operated with 200 ns elec-trical pulses. The technique is also applied to GaAs HEMTs for the first time, demonstrating the versatility of time-resolved Raman thermography.
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physica status solidi (a), 2007
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2007 IEEE Compound Semiconductor Integrated Circuits Symposium, 2007
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IEEE Electron Device Letters, 2000
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IEEE Electron Device Letters, 2000
We report on the development of time-resolved Raman thermography to measure transient temperature... more We report on the development of time-resolved Raman thermography to measure transient temperatures in semiconductor devices with submicrometer spatial resolution. This new technique is illustrated for AlGaN/GaN HFETs and ungated devices grown on SiC and sapphire substrates. A temporal resolution of 200 ns is demonstrated. Temperature changes rapidly within sub-200 ns after switching the devices on or off, followed by
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IEEE Electron Device Letters, 2000
Time-resolved Raman thermography, with a temporal resolution of , was used to study the thermal d... more Time-resolved Raman thermography, with a temporal resolution of , was used to study the thermal dynamics of AlGaN/GaN electronic devices (high-electron mobility transistors and ungated devices). Heat diffusion from the device active region into the substrate and within the devices was studied. Delays in the thermal response with respect to the electrical pulse were determined at different locations in the
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