Flow Rate Regulation of a Variable Speed Driven Pumping System Using Fuzzy Logic

The use of variable speed drives in fluid pumping applications represents an energy efficient solution for achieving adjustable flow rate. In particular, centrifugal pumps driven by induction motors can be operated at power efficiency levels close to the maximum value while delivering a wide range of flow rates. However, the prevailing head and flow are influenced by the nonlinear characteristics of both the pump and pipe/tank systems. While conventional flow controllers are designed, based on a linear model of the pumping system, their performances may degrade due to large disturbances and uncertainties in the system curve parameters. This paper presents a flow control system based on fuzzy logic, for a centrifugal pump driven by a field-oriented 3-phase induction motor. The fuzzy controller adjusts the torque command for the motor, so that the flow rate of the pumping system is regulated to the reference setting. Simulation tests performed show that the proposed scheme is able to track the flow rate command under large disturbances in the system parameters, while operating the pump in its best efficiency region.