Microcontroller-based simple maximum power point tracking controller for single-stage solar stand-alone water pumping system

A simple microcontroller-based maximum power point tracking controller is proposed for a single-stage solar stand-alone water pumping system for remote, isolated, and nonelectrified population, where less maintenance, low cost, and an efficient system is of prime interest. It consists of a photovoltaic (PV) module, a DCAC converter utilizing space-vector pulse-width modulation, an induction motor coupled with a water pump, a voltage sensor, and a current sensor. A space-vector pulse-width modulation-controlled DCAC converter aided by a fast-acting onoff supervisory controller with a modified perturb-and-observe algorithm performs both the functions of converting PV output voltage to a variable voltage, variable frequency output, as well as extracting the maximum power. A limited variable step size is preferred during transient state, and a steady frequency, which is calculated on the basis of steady-state oscillation, is set during steady state. A fast-acting onoff supervisory controller regulates DC link voltage during steady state and enables maximum power point tracking algorithm only during transient state to draw a new voltage reference. In the event of low voltage, the controller switches off the motor but continuously scans for an available PV voltage. The system is not protected against an overcurrent because the maximum current is equal to its short circuit current. The 16-bit microcontroller dsPIC6010A (Microchip Technology, Inc., Chandler, AZ, USA) is used to implement the control functions. The proposed controller is verified through simulation as well as tested in the laboratory prototype model. The simulation and experimental results show good correlation. Copyright (c) 2011 John Wiley & Sons, Ltd.