Reduction of thermal cycling to increase the lifetime of MOSFET motor drives

The variation of the temperature in semiconductors, caused by the load profile, results in the long term in material fatigue. A distinction can be made between the average temperature and the temperature swing, where the temperature swing has a significant effect on the lifetime of a semiconductor. Therefore, the auxiliary-pole topology is proposed to reduce the temperature swing of the MOSFETs in a motor drive. The auxiliary-pole topology divides the load current over two switching-legs and circulates a current when there is a low or zero load current. The conventional half bridge topology is used as a benchmark. Both topologies are simulated with the same load profile and with an equal total amount of silicon. The results show a reduction of the temperature swing and an increase in average temperature of the switches in the auxiliary-pole topology. This leads to an significant improvement in cycles to failure and time to failure.