Servo System Design For Photocell Holder

In order to improve photoelectric conversion efficiency of solar panel, a photocell holder servo system is designed. It applies PID control to adjust angle offset between sun position and panel position, to achieve accuracy tracking of sun position, making the received solar maximal on the panel.Through astronomical theory, sun position can be determined at different moments, and sends to controller as guide data. Panel position can be determined by high-precision position sensitive detector, and gives back to controller as feedback. According to change characteristics of angle offset at different times, a segmented method is applied to adjust deviation, that is,|σ|= 9°as a boundary point, if |σ|>9°, the controller regulates the actuator speed by changing impulse frequency, to make system reached the expected position quickly, ensuring the rapidity of system; if |σ|≤9°, actuator is operated with a constant speed, and the PD control way is applied to correct errors in advance, in order to ensure system tracking effect. Stepping motor, whose control signal is angle, is chosen as actuator, and runs with micro step distance angle by current subdivision driver, so as to improve system position control precision.At last, by analyzing performances of the servo system through MATLAB simulation experiment, the results show that segmented control method is not only shortens locating time, but also decreases system steady-state error, enhances tracking precision, which make panels quickly and accurately adjust to the position that sun beam is vertical to. This method effectively improves photoelectric conversion efficiency, and provides a kind of learning methods for similar tracking system.