The insulated gate bipolar transistors (IGBTs) are widely used in many modern fields of power electronics that are related to power conversion, transmission and distribution. Today IGBTs with blocking voltages up to 6.5 kV are commercially available, allowing simple and robust two-level topologies to be used in applications with nominal DC voltages up to 3.6 kV without the need of series connection of several IGBTs. The other advantages of IGBTs are easy driving and snubberless operation. On the other hand, the high-voltage IGBTs have limited current capability and high power losses, resulting in limited switching performance due to thermal issues. Therefore, thermal management became one of the most important aspects in the development of high-voltage IGBT converters. The accurate estimation of power losses is an important step in thermal management system design [1-3]. A number of calculation methods have been proposed. One of the approaches is based on the switching functions or coefficients obtained through measurements to guide the simulation during switching transients [4, 5]. However, this method requires a number of parameters to be extracted from the test waveforms. Another approach is based on the use of simple functions derived for losses based on typical switching waveforms [6, 7]. This method was extended in [1, 8] by deriving a set of formulae for switching losses based on the predicted current and voltage waveforms of the device. In this method the predicted waveforms conform to the physics of the switching process and take into account the dependency of the switching losses on various factors such as the switching voltage, switching current, stray inductance and the reverse recovery process of the freewheeling diode [8]. Another advantage is that it requires a smaller number of parameters from the test waveforms.
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