Performance Analysis and Enhancement of a PV Fed Sensorless BLDC-Motor for an Efficient Water-Pumping System

The presented paper aims at studying, analysing and improving the operating characteristics of a proposed photovoltaic (PV) pumping system based upon a sensorless brushless DC (BLDC) motor. The system under study consists of a PV array feeding a BLDC motor via boost converter and three-phase inverter for driving a centrifugal pump. An appropriate PV-array is designed such that it is capable to operate and produce the maximum power under a predetermined designed irradiation level. Due to the problems and difficulties associated with the hall sensors which are necessary for the BLDC-motor operation, an appropriate sensorless control technique is suggested for rotor-magnet position estimation. A suggested control strategy is presented to improve the performance characteristics of the overall system under different operating conditions. The main objective of the presented control strategy is pushing the PV array to operate and track the maximum power point (MPP) when the irradiation level is less than the designed level via regulating the boost converter duty-cycle aided with the well-known Perturb and Observe (P and O) scheme for maximum power point tracking (MPPT). However, the estimated hall-sensor signals are directly control the operation of the employed three-phase inverter. Moreover, when the irradiation level is greater than the designed level, a simple PWM algorithm is proposed to regulate the inverter operation for controlling the motor speed to be maintained constant at the rated value. In this mode, the boost converter is operated with a constant duty cycle as there is no need for using the MPPT technique. Some of the obtained simulation results is presented and discussed to illustrate and certify the usefulness of the proposed control strategy.