Multi-level inverter for driving PV water pumps

Abstract

In this research, we have developed a system for driving PV water pumps based on multi-level inverters, where cascaded H-Bridge-MLI was studied to improve conversion efficiency, by testing three different strategies to generate pulses for electronic elements and determining the best strategy between them, then compare it with the traditional 2-LEVEL inverter circuit.  The results showed the superiority of Phase Disposition (PD-PWM) strategy, where the THD Ratio of the voltage and current wave was minimal compared to the other strategies at different carrier wave frequencies in addition to studying the effect of the number of voltage levels on THD Ratio, and when we simulated a three phase (Cascaded H-Bridge 7 level) inverter circuit based on PD-PWM strategy at 3000 Hz carrier wave frequency, the THD Ratio of voltage wave has not exceed 11%, While in the traditional 2-LEVEL inverter, the THD Ratio of voltage wave is about 66%, which shows the importance of MLI to improve conversion efficiency. The proposed driving system operates according to the v / f control system to control the pump speed in proportion to the intensity of the solar radiation while maintaining a constant torque, and also works to track the maximum power point MPPT according to P&O algorithm, and when we simulated the system by MATLAB / SIMULINK the results showed the effectiveness and reliability of the proposed system