05 Fakultät Informatik, Elektrotechnik und Informationstechnik

Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/6

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Author: search.filters.author.Ruthardt, Johannes

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    Comprehensive comparison of a SiC MOSFET and Si IGBT based inverter
    (2019) Nitzsche, Maximilian; Cheshire, Christoph; Fischer, Manuel; Ruthardt, Johannes; Roth-Stielow, Jörg
    The investment which is necessary to replace Si IGBTs with SiC MOSFETs in medium to high power DC-AC inverters needs to be balanced carefully against the advantages SiC offers. This paper compares a 20 kW Si IGBT inverter with a 20 kW SiC MOSFET inverter. The power semiconductor components are operated identically in a modular half bridge module to ensure comparability. Thereby the measurement of the switching losses is explicitly not the focus but the overall efficiency while taking volume, current ripple, switching frequency and inductance into account. The limits of reasonable operating range shall be evaluated and an overview on the benefits of SiC on system level will be given.
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    Junction temperature control system to increase the lifetime of IGBT-power-modules in synchronous motor drives without affecting torque and speed
    (2020) Wölfle, Julian; Nitzsche, Maximilian; Ruthardt, Johannes; Roth-Stielow, Jörg
    Load changes of electrical machines driven by inverters cause temperature swings of the semiconductor devices in IGBT modules of the inverters. These temperature swings lead to mechanical strain in the different material layers of the IGBT-power-modules and limit the numbers of cycles to failure and therefore reduce the lifetime of the IGBTs. This paper presents a temperature control system which is paralleled to the standard torque control system. It aims to reduce the magnitude of temperature swings of the semiconductor devices of IGBT modules caused by load changes of an interior permanent magnet synchronous machine. The principle method is, to increase the temperature of the semiconductor devices of the IGBT-modules by creating higher power losses during low load conditions of the machine without affecting torque and speed. This reduces the magnitude of the load induced temperature swings of the semiconductor devices of IGBT-modules and increases its lifetime at the cost of increased power losses. Three variables have been identified that influence the power losses in inverter modules without necessarily affecting the output power of the permanent synchronous machine. These variables are switching frequency of the inverter, length of the clamping area when a discontinuous modulation is applied and the reactive component of the inverter current. The influence of each variable which regards to the losses in the IGBT-power-modules is explained and the related control methodology is described. The analytic results are verified by experimental results obtained from a test set up.