An adaptive, observer-based switching method for B4 inverters feeding three-phase induction motors

摘要

A four-switch inverter called the B4 inverter is a reconfigured topology of a B6 inverter, one leg of which is damaged. The four-switch topology provides the overall system with fault-tolerant characteristics. However, this reconfiguration will not only change the system dynamics but also degrade the system performance. For overcoming with these issues, this paper presents an adaptive switching method based on DC-link voltage control. In the proposed method, the selection of active vectors and the calculation of switching times are made according to an adaptive, observer-based algorithm which will reduce DC-link voltage oscillations and adjust unbalanced currents fed to induction machines. In this algorithm, an online, designed observer is utilized so as to estimate the DC amount of the DC-link voltage. Applying this method, we will decrease flux and torque ripples as well as increase the inverter efficiency and performance. The simulation results presented in the MATLAB environment evaluate and validate the performance and effectiveness of this approach.