Three phase Quasi Z source inverter fed solar PV wide input voltage range for BLDCM pumps

Abstract

This paper is based on the performance of the Brushless Direct Current Motor (BLDCM) centrifugal pump set fed by wide input voltage solar photovoltaic (PV) generator using Quasi Z Source Inverter (QZSI). The aim of this paper is to develop water pumping control loops enabling the system load line operating point to track and match that of the centrifugal pump best efficiency point (BEP) along the Head Flow rate curve (HQ curve). In this way, the pumping scheme operates at optimal points and achieves highest allowable centrifugal pump efficiency with long-term safe operation. Considering the wide input voltage range of solar photovoltaic (PV) power generator, this paper presents a novel BLDCM adjustable speed drive to ensure continuous water pumping at the highest allowable efficiency. The designed water pumping system has been modeled and studied in Matlab Simulink. It was found that throughout the steady state operation under highly variable solar PV generated power, the system load line operating point was always in the vicinity of that of the centrifugal pumps BEP. The recorded best efficiency point tracking (BEPT) was found to be 96%. Presented result means that with the proposed BEPT mapping algorithm, the power drawn from the PV generator is optimal for the intended usage of water transport in a context of highly variable supplied power.