Implementation of cascaded H-bridge DC-link inverter for marine electric propulsion drives

Abstract This paper presents a single-phase seven level Cascaded H-Bridge DC-Link (CHBDCL) inverter for marine electric propulsion drives. The speed of propulsion drive can be changed by CHBDCL inverter by converting DC output from the rectifier to variable output voltage with or without change in frequency. The proposed CHBDCL inverter generates more output voltage with minimum harmonic content than classical Multilevel Inverters (MLIs). The CHBDCL inverter necessitates only ‘m + 3’ power devices for ‘m’ number of levels, although the classical MLIs requires ‘(2m − 1)’ power devices. CHBDCL inverter can have the effective performance by utilizing unipolar Sine Pulse Width Modulation (SPWM) and unipolar Space Vector PWM (SVPWM) with sine carrier. The effectiveness of the proposed CHBDCL inverter topology has been verified by using MATLAB/SIMULINK for various modulation indices in terms of voltage levels and harmonic analysis. Furthermore, an experimental setup involving pulse generation from a Field Programmable Gate Array (FPGA) has been used to test the performance of the proposed CHBDCL inverter.