Field oriented control of stepper motors for a mini heliostat tracking

Solar tower power plant has become the most promising concentrated solar power technology for the production of thermal and electrical energy because of its advantages including high improvement rate, possibility of small scale, hybridization, cogeneration. However, the high cost and the low efficiency of the heliostats field constitute an obstacle of this technology development. In this paper, a simple heliostat with an azimuth and altitude mechanism is implemented. The mirror position is determined thanks to the astronomical equations and Snell Descartes Law's. On each axis, a hybrid stepper motor is placed for moving the mirror. To improve the accuracy of the tracking system, this paper proposes the field oriented control like a positioning control technique of heliostats stepper motors. Simulations of the tracking are done in Matlab/Simulink. The results obtained show that the positions are reached without overshooting and with response times of 0.269 and 0.285s respectively for altitude and azimuth axis. According to the results of simulations, the field oriented control is a good method for heliostat motors control.