Fast space vector modulation algorithm for multilevel inverters and its extension for operation of the cascaded H‐bridge inverter with non‐constant DC sources

Abstract

A major advancement in the research area of space vector modulation (SVM) in recent years is the introduction of the nearest three vector algorithm. Nonetheless, computational intensity is still a drawback of SVM methods in real time applications, especially in the case of multilevel inverter operation. A very fast and scalable SVM algorithm is introduced in this study, referred to as the fixed coordinate sub-triangle SVM (FCST-SVM) approach. The proposed method permits the determination of switch states and efficient calculation of switch on-time durations for a given N-level inverter topology. Calculations are performed based on a proposed sub-triangle approach with fixed coordinates in the space vector diagram. Avoiding calculating the coordinates of the nearest three voltage vectors is a significant advantage of the proposed algorithm compared with previous SVM approaches applied to multilevel inverters. An example of the application of this method is presented for the multilevel cascaded H-bridge inverter when non-constant isolated DC sources are subjected to random voltage deviations. MATLAB simulation results verify the feasibility of the proposed approach. Experimental results, using a TMS320F2812 digital signal processor, are also presented to verify the effectiveness of the proposed approach in decreasing the computational overhead in comparison with the conventional SVM method. For example, it is found that computational requirements for SVM decrease by a factor of 9.5 compared with the conventional method in the case of a three-phase nine-level cascaded H-bridge inverter.