A Modified PWM Scheme to Improve the Power Quality of NPC Inverter Based Solar PV Fed Induction Motor Drive for Water Pumping

Solar photovoltaic (PV) powered water-pumping systems are proving to be a very effective in areas where the electric grid is not available. The pulse width modulation (PWM) technique, the power quality, and the torque ripple of an induction machine employed in the solar PV fed water-pumping applications have always been a concern. This paper proposes a modified reference based PWM scheme for a neutral point clamped (NPC) inverter based induction motor drive (IMD) for the solar PV fed water-pumping system. This work mainly focuses on the improvement of power quality of induction motor, converter switching loss, and torque ripple profiles of the IMD. The proposed PWM scheme utilizes ninth harmonic and trapezoidal signals to form the modulating signal, which produces balanced and symmetrical gate drive signals for the NPC inverter employed in the IMD. The generated gate drive signals reduce total harmonic distortion (THD), switching and conduction power losses, and torque ripple of the IMD. The IMD with the proposed PWM switching scheme is examined in the all possible operating conditions of the induction motor. Comparative performance analysis of the proposed PWM scheme with the existing PWM schemes are also conducted in MATLAB/Simulink platform to prove the superiority of the proposed PWM scheme.