Lifetime Extension Technique for Voltage Source Inverters Using Selected Switching States-Based MPC Method

In a power electronic system, a control objective is to improve efficiency and reduce thermal stress in converters in order to increase the lifetime of devices. To achieve this, minimizing losses is crucial. The objective of this research paper is to present a method aimed at decreasing individually switching losses in voltage source inverters (VSI). The proposed technique uses per-phase model predictive control (MPC) with preselected switching states to target specific phase legs and achieves corresponding loss reduction. With the information of predicted reference voltages, the developed preselection algorithm determines the non-switching area of the most aged leg and corresponding switching states among available voltage vectors of VSI. The switching loss reduction in the most aged leg is achieved by selecting the optimal switching state among preselected voltage vectors based on a pre-established optimal criterion. The thermal stress of the most aged leg will be reduced, and therefore its lifetime will be increased, resulting in improving the reliability and lifetime of the entire VSI. Finally, the effectiveness of the proposed per-phase MPC method with preselection of switching state is verified by both simulation and experimental results.