Thermal Cycling Effect in a Traction Inverter for Star-connected and Open-end Winding Permanent Magnet Synchronous Motors with Nearly Constant Losses Current Regulation

One of the causes of faults in the electric drive is the failure of the power semiconductor module. Semiconductors degrade under the effect of thermal cycles. Thermal aging of materials occurs due to temperature difference between the elements of the power module as well as difference of their thermal expansion coefficients, which eventually leads to the destruction of the power module construction. The influence of thermal cycles is most expressed in traction drives, which are characterized by modes with low speeds and variation of commanded torque in time. This article considers a BMW i3 electric drive model and an open-end winding drive with Nearly Constant Losses Current Regulation for evaluating thermal cycles in a power module. The new European driving cycle was used as a test cycle for both drives. It is shown how the proposed algorithm makes it possible to reduce the thermocycling effects in semiconductor devices.