An Algebraic Modulation Strategy for 3L-NPC Converters With Inherent Neutral-Point Voltage Balance Capability

This letter proposes an algebraic modulation strategy for the three-level neutral-point-clamped converters. The duty-cycle-assignment problem is first transformed into the algebraic-solution problem. Then, according to the algebraic theory, the general solution of the modulation matrix is obtained. By properly designing the free parameters in the general modulation matrix, various neutral-point voltage (NPV) balancing methods can be constructed conveniently. In addition, the NPV balance is easily realized without additional control effort. Compared to the existing modulation strategies, the proposed strategy is simple and easy-to-implement. The feasibility of the proposed strategy is validated by laboratory experiments.