Analysis of optimum matching of a DC series motor driven centrifugal pump to a photovoltaic generator

Abstract

Direct coupling between a photovoltaic (PV) generator and a monoblock DC series motor connected with ventilator load torque centrifugal pump has been analyzed theoretically as a function of the no flow motor-pump speed (w₀) and the water head of the pump. The value of w₀ is directly related with motor terminal voltage which has been derived. The condition of the maximum motor-pump efficiency has been deduced mathematically in terms of the speed-torque constant K₁ at a given w₀ for different water heads. The variation of w₀ and perfectly matched motor constant (M₀) have been calculated at various solar insolation and different water heads. From these theoretical studies, the optimum matching condition has been suggested according to the requirements. One optimally matched monoblock DC series motor and centrifugal pump, of 125 W, was chosen for study. The calculated coupling efficiencies such as electrical energy, mechanical energy, and hydraulic energy of the pump, have been discussed. Some of these results are also compared to information available in the literature.