A Mapping-Based SVM Method for Balancing DC Input Voltage of a NPC Five-Level Inverter

Abstract

A multi-level inverter has potential advantages in high blocking voltages and reduced harmonics. However, it has a technically challenging subject that the DC input voltages must be balanced. This paper proposes and investigates a new double-mapping-based space-vector modulation (SVM) method to solve the subject without any additional circuit. The proposed method consists of two steps. One is the space-vector (SV) map data generation for the five-level NPC inverter based on a general principle to utilize redundant SVs. The other is the optimal selection of the SV pattern which balances the DC input voltages based on the double-mapping-based SVM method which has two different kinds of control schemes for low and high modulation indexes. The proposed method is investigated and validated through simulated results by a digital control system.