A solar PV water pumping solution using a three-level cascaded inverter connected induction motor drive

This paper presents a single-stage solution for PV fed three-phase induction motor (IM) water pumping system. The given solution uses time tested, two two-level cascaded H-bridge inverters to give three-level voltage output to the IM pump drive. The proposed system is operated using the control strategy which includes Maximum Power Point Tracking (MPPT), Space Vector Pulse Width Modulation (SVPWM) and V/f control. The MPPT algorithm generates the modulation index 'ma' which is used to operate the cascaded inverter and generates three-level output voltage under all environmental conditions. This helps in improving the THD of IM phase current, thereby reducing the torque ripple. In addition, the 'ma' value is used to define the IM operating frequency. This helps in further improvement in the IM performance. All the details of the proposed system regarding the system modeling along with simulation and experiment results are given in the manuscript. In addition, the comparison of the propsoed solution with the conventional system i.e., two-level inverter connected PV pumping system is presented.