Efficient online-algorithm for the temperature cycle recording of an IGBT power module in a hybrid car during inverter operation

To improve the lifetime calculation accuracy of IGBT power modules in hybrid cars it is necessary to qualify and adjust the simulation-based load profiles through field studies with test vehicles. For this purpose an online-algorithm is presented, which enables the calculation and storage of all temperature cycles a power modul in a test vehicle is exposed to during inverter operation. Unique feature of the online-algorithm is a reduced computing power of 85 per cent and a lowered storage capacity of 99 per cent compared to a conventional algorithm used in desktop computers. Despite these major reductions the calculated lifetime of the power module deviates less than 1 per cent. The properties of the online-algorithm favor its implementation on the microcontroller of the control board and enable the simple determination of load profiles by field studies. Within this paper the function and the validation of the algorithm is outlined.