Equivalent temperature estimation-based FCS-MPC for thermal stress balance of 3L-NPC traction inverter

Abstract

This paper proposes an equivalent temperature estimation-based finite control set model predictive control (ETE-FCS-MPC) method to balance the thermal stress among transistors in three level neutral point clamp (3L-NPC) traction inverters, which can be used to prolong the whole service life and improve the reliability of the traction inverter. Compared with other methods, the proposed ETE-FCS-MPC method requires lesser calculation without additional sensor. Firstly, an energy loss-based equivalent temperature estimation method is proposed to avoid the complexity of junction temperature prediction. Secondly, an energy variance-based thermal stress balance control objective is introduced. Then, a normalized evaluation function is established to select the optimal switching state. Finally, the effectiveness of this method is verified on hardware-in-the-loop tests.