| Summary: | 碩士 === 國立勤益科技大學 === 電機工程系 === 99 === The aim of this thesis is to design and control a two axis sun tracker system. The sun tracker system consists mainly of a tracking mechanism, a sun location sensor, and an electrical control system as follows.
1.Two axis sun tracker mechanism design: The mechanism of sun tracker system has mainly three parts, a horizontal axis base, a vertical axis loading platform, and a control box. The horizontal axis base and vertical axis loading platform are driven by high gear ratio DC motors to reduce the motor size and the rated power. The designed gear ratio is higher enough to load middle size solar cells.
2.The sun location sensor includes sensor mechanism and CdS (Cadmium Sulphide) sensor circuit. The sensor mechanism is design for arranging four CdS on four symmetrical ramp surfaces to benefit the CdS have different sensitivity to distinguish different light source.
3.The electrical control system consists mainly of servo control card, CdS sensor circuit, and programming. The servo control card uses PIC18F8720 chip as the control kernel. Integrating the necessary power MOSFET and encoder signal circuit it can execute the position loop control of DC servo motor. The CdS circuits are divided as north-southern and west-east two groups. Each group contains signal processing circuit to ensure signal measurement. Different light location will generate voltage difference from the sensor circuit. Zero voltage difference denotes the loading panel is orthogonal to light beams.
Finally, the developed two axis sun tracker system is tested using incandescent lamp, fluorescent lamp, and sunlight to demonstrate the feasibility and success. The experimental results show that the loading panel can track the different light source always, no matter the incandescent lamp, fluorescent lamp, or sunlight.
Keywords: sun tracker, PIC microcontroller, solar cell, solar array, servo control.
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