Digital Control Of Bi-directional Dc-dc Converter On Stand-alone Pv System

With the energy becoming less and less and the pollution of the environment becoming more and more serious, people begin to focus on the research and development of new energy. Solar energy power generating has many advantages of no-pollution, non-noise and inexhaustible, etc. It has been drawn worldwide attention and it has an important place in the power supply system in the future. This thesis is dead against the Bi-directional DC-DC Converter of stand-alone PV system and academic and testing research in the pure digital control of solar energy power generating based on TMS320F2812 is done.Bi-directional DC-DC Converter (BDC) is the DC-DC converter that power can flow in either direction between two DC sources. In this paper, the fundamental of solar energy power generating and the basic operation principle of DC-DC converter are analysed firstly,then introduces the working principle of the Bi-directional DC-DC converter, and the structure of main circuit of it is studied from simplest to more complex. Based on the above, the hardware and the software are designed. The high voltage (HV) is connected to the photovoltaic cell array, and the low voltage (LV) is conected to the. lead acid batteries.A digital PID controller is designed to make the system has a satisfactory transient response against the disturbance. The control circuit can monitor the size of the voltage, which will decide the converter working on the state of buck or working on the state of boost. When the main circuit is working on the state of buck, the photovoltaic cell array will charge the batteries and the software will select charging pattern (constant voltage to charge or contant current to charge) actomatically by judging the voltage of the batteries. On the other hand, the batteries will discharge on current voltage when the main circuit is working on the state of boost. Over-voltage, over low voltage and over-current are protected by hardware and software.The design of the Bi-directional DC-DC Converter of stand-alone PV system, the design of the hardware and software, realization of digital PID controller, the analysis of experimental results and optimization process are all given detailedly in this paper.