A Single-Phase Step-Up Seven-Level Inverter With a Simple Implementation Method for Level-Shifted Modulation Schemes

This paper proposed a single-phase seven-level inverter topology with a simple implementation method for level-shifted modulation schemes, which includes two novelty work. One aspect of the work is the proposed inverter topology that integrates a three-time step-up ratio and capacitor voltage self-balance capability. Compared to the existing single-phase seven-level inverters, the proposed inverter reduces the number of power switches and the voltage stresses across them. The other aspect of the work is a new way to implement level-shifted modulation schemes (level-shifted carrier modulation scheme and level-shifted sine modulation scheme) by three basic steps: (1) obtaining modulation logic based on Karnaugh Map technique; (2) determining a level-shifted modulation scheme; and (3) software implementation using the general-purpose input output(GPIO) terminals and CPU timer interruption function of a DSP chip. Therefore, complex trigonometric calculations of the traditional implementation methods for carrier modulation schemes are replaced by simple logic operations of the proposed implementation method, and thus extra logic chips used in the traditional implementation methods are not necessary for the proposed implementation method. Both simulation and experimental results are presented to verify the proposed inverter topology and the proposed implementation method for level-shifted modulation schemes.