The Research Of Nonlinear Characteristics And Compensation Based On Solar Tracking Servo System

Solar energy is one of the ideal renewable energy. Photovoltaic power generation is one of the ways to use solar energy。 The best way to improve the receiving efficiency of solar energy is automatic tracking technology which the solar battery board in real-time and the sun’s rays remain perpendicular. The main conditions of which evaluate the track- ing quality are tracking accuracy and stability.Since the tracking system with a very large light-receiving face is the system of very big, a low speed, big moment of inertia. The adjustment of angle is by means of a mechanical transmission mechanism a transmission mechanical device.The angle adjustment is accomplished by a mechanical device, the output and the input has deviation and affect the accuracy of the solar tracking system. So the research nonlinear of solar tracking servo system and a closed-loop tracking control in the cloud weather which improve the tracking accuracy of the servo system has important significance.First of all, the basic theory of the solar tracking servo is discussed in the paper. Two-axis tracking servo system of based on three-phase hybrid stepper motor is as the object of study, Analysis of the factors affecting the stability and precision of tracking. It include the nonlinear of hybrid stepping motor and friction nonlinear actuator. The main non-linear actuating motor is out of step problem whose existence during the operation, propose a solution to the problem by using closed-loop control mode which is based on subdivision axis orientation of space vector control, using sliding mode variable structure observer control instead of mechanical sensors, the position and speed of the rotor are estimated to complete the motor position sensorless control, the speed or position of detected signal feedback to logic control circuitry in order to determine the corresponding phase power device on-off. The method which is chosen to solve the problem of out of step is verified the reasonableness by simulation results.For tracking control system mechanical devices, friction nonlinear is a major factor. Friction disturbance have a great effect on the low-speed performance of the servo actuator and cause the system to run unstable, generating low jitter or crawling. Since solar tracking servo system can work in the outdoor environment in most cases which a relatively large changes in the environment, use the compensation method of not based on friction model and establish of a mathematical model considering friction disturbance of tracking servo system, use the compound control of sliding disturbance observer and sliding mode controller to compensate for friction disturbances of the servo system and demonstrate the stability of the system using the Lyapunov function, the effectiveness of the algorithm is verified by the simulation.In order to ensure the accuracy and reliability of the tracking servo system that adopt the day trajectory and the image processing of the dual mode tracking closed- loop control method which is running in the cloud weather obscured the weather, and proposes a n algorithm for extraction of sun centroid. Defogging method based on median filter to remove the fast channe l solar image in the dark haze and enhanced index using a fast maximum stable feature regions(MSER) extraction algorithm to extract the solar area, finally calculate the centroid of the sun. Experimental verification of the proposed algorithm for complex weather conditions is verified by experiment, it can accurately extract the centroid of the sun in the fog and haze which ensure tracking accuracy of the closed- loop tracking.