Algorithm for On-line Definition of Switching Sequences for Space Vector Modulation of Asymmetrical Cascaded Multilevel Converters

This paper proposes an algorithm for the on-line definition of switching sequences for Space Vector Modulation (SVM) of the low voltage power cells of asymmetrical multilevel cascaded converters. Initially, an algorithm to define on-line the redundancies of the three nearest low voltage vectors is described in details. The first vector of the new sequence is chosen so as to minimize the switching losses between two consecutive reference samples. Then, the remaining vectors are organized within the switching period in a way such as to have the least number of commutations. As a result, minimum switching losses is achieved, even in the transition between sectors. Furthermore, the algorithm can also define sequences for any fault condition, avoiding the use of different look-up tables. Finally, experimental results are shown to validate the proposed algorithm.