15-10-2010, 05:24 PM
Prepared by:
Thanh Phu Nguyen
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Abstract
“Solar Panel Maximum Power Point Tracker”. As the name implied, it is a photovoltaic system that uses the photovoltaic array as a source of electrical power supply and since every photovoltaic (PV) array has an optimum operating point, called the maximum power point, which varies depending on cell temperature, the insolation level and array voltage. A maximum power point tracker (MPPT) is needed to operate the PV array at its maximum power point. The objective of this thesis project is to build two MPPT in parallel to charge a 12-volts lead acid battery by using a field wired 83 Watts PV array.
The design consists of a PV array, a 12-volts lead acid battery, DC_DC Boost converters (also known as step-up converters) and a control section that uses the PIC16F873 microcontroller. The control section obtains the information from the PV array through microcontroller’s Analog and Digital (A/D) ports and hence to perform the pulse width modulation (PWM) to the converter through its D/A ports. Battery’s state of charge is also controlled by the microcontroller to protect the battery from overcharged.
The Incremental Conductance method is used as an algorithm to track the maximum power point of the PV array. The performance of the Incremental Conductance algorithm in tracking maximum power point is better than the Perturbation and Observation algorithm. By using Incremental Conductance algorithm the MPPT is able to track the maximum power point of the PV array quickly under rapidly changing in sun light intensity. While the Perturbation and Observation algorithm tends to deviate from the maximum power point under this condition.
