Novel Thermal Management Strategy for Improved Inverter Reliability in Electric Vehicles

Requirements for electric vehicle (EV) propulsion systems—i.e., power density, switching frequency and cost—are becoming more stringent, while high reliability also needs to be ensured to maximize a vehicle’s life-cycle. Thus, the incorporation of a thermal management strategy is convenient, as most power inverter failure mechanisms are related to excessive semiconductor junction temperatures. This paper proposes a novel thermal management strategy which smartly varies the switching frequency to keep the semiconductors’ junction temperatures low enough and consequently extend the EV life-cycle. Thanks to the proposal, the drivetrain can operate safely at maximum attainable performance limits. The proposal is validated through simulation in an advanced digital platform, considering a 75-kW in-wheel Interior Permanent Magnet Synchronous Machine (IPMSM) drive fed by an automotive Silicon Carbide (SiC) power converter.This work has been supported in part by the European Commission through ECSEL Joint Undertaking (JU) under Grant Agreement No. 783174 (HiPERFORM project), by the Government of the Basque Country within the research program ELKARTEK as the projects ELPIVE (KK-2019/0006) and ENSOL 2 (KK-2020/00077), by the Government of the Basque Country within the fund for research groups of the Basque University system IT978-16, by the Government of Spain through the Agencia Estatal de Investigación Project DPI2017-85404-P, and by the Generalitat de Catalunya through the Project 2017 SGR 872