Light Tracking Servo System 



Sun tracking systems are very effective in increasing the efficiency of photovoltaic (PV) arrays, and are essential for concentration PV systems. The following paper discusses a light tracking servo model which has been built to simulate the movement of a PV array. A mathematical model is developed and a qualitative comparison of the mathematical model and
the actual physical model is done to demonstrate the dynamics of a light tracking servo system. An overall transfer function for a permanent magnet direct current (dc) motor was also developed. This subject is treated as a separate Case Study in this course (see Case Study F). The motor transfer function is used in the development of an overall transfer function for the light tracking servo system. Using the overall transfer function, a computer simulation program within Matlab is used to simulate the dynamics of the servo system. A qualitative analysis of the Matlab results and the dynamics of the working physical model are compared to clearly illustrate the important dynamics of the system. The light tracking system consists of a permanent magnet dc motor, a directional light detecting circuit, and an amplifier to drive the motor. Refer to the model and to Fig. 6E. 1 for the physical configuration and a simple block diagram representation. Two photo sensitive resistors are physically mounted on a triangular plexiglass mount so that when the panel (the aluminum bar) is perpendicular to the light source, each receives an equal amount of irradiance. When one receives more light than the other, the panel is not aligned properly and an error voltage results. The error voltage is used as a command to an amplifier circuit to drive the motor and align the panel to be perpendicular to the light source beam. The following...
characters left: