A Model-Based Control Scheme for Modular Multilevel Converters

This paper deals with the modeling and nonlinear control of modular multilevel converters. Two nonlinear coordinate transformations are introduced, which lead to a compact and clear representation of the differential equations. Two candidate outputs are discussed, which lead to an internal dynamics of second or third order, respectively. Only the second candidate output is analyzed further. For the corresponding internal dynamics, the conditions which ensure boundedness are examined. A quasi-static feedback leads to a linear input-output behavior. Simulations show the usefulness of the results.