A normalized compensation method for voltage nonlinearity of three-level ANPC inverter

This paper proposes a normalized compensation method for voltage nonlinearity of the three-level active neutral point clamped (3L ANPC) inverter. The operation of the 3L ANPC inverter includes the voltage nonlinearity caused by voltage errors, which are induced by the nonlinear components of switching devices and their operations. Since this voltage nonlinearity seriously distorts the phase current, it must be compensated to improve the quality of power conversion. For the 3L ANPC inverter, however, the voltage nonlinearity varies depending on the topology and modulation scheme, as well as the power factor of the system. Although many conventional methods have been proposed, these methods do not fully deal with the factors affecting the voltage nonlinearity. In this paper, a normalized compensation method for the voltage nonlinearity considering the characteristics of the 3L ANPC inverter and the power factor of the system is proposed. Two general topologies and modulation schemes of the 3L ANPC inverter are discussed in this paper, and the voltage nonlinearity is analyzed to derive the compensation components. By executing the compensation based on these analyses, the proposed method ensures its performance remains consistent across operating conditions, and is simply implemented. The effectiveness of the proposed method is verified by experimental results.