A Photovoltaic System With Voltage-Based Maximum Power Point Tracking

As a non-polluting renewable energy, solar energy has broad prospects for application. Therefore, photovoltaic power generation technology, which can directly convert solar energy to electricity, is highly valued. But because of the low efficiency of solar cells, the application of photovoltaic power generation system is constrained by its cost. In order to improve the efficiency, the technique of maximum power point tracking (MPPT) is widely used to make sure that solar cells always output maximum power under various environmental conditions.Based on the study of characteristics of solar cells and photovoltaic power generation system, this paper has successfully designed a MPPT chip which uses constant voltage method as its MPPT method. The chip is implemented by analog circuits with solar cells as its input and battery as its output.The content is divided into three parts. The first part is theoretical study, from which constant voltage method is proved to be feasible and is selected. The second part is circuit design, which includes system design and module design. System stability analysis and compensation circuit design of the particular system in this paper are discussed in detail. And traditional structures are adopted to implement the function blocks. The third part is simulation and test of the chip. In simulation process, the model of solar cells is constructed successfully and it can be widely used in photovoltaic system design process. The test results confirm that all the main performances of the chip were consistent with expectations.The chip was designed and fabricated in 1.5μm BCD technology. The simulation and test results showed that the real time maximum power point can be tracked under the control of the chip. It has the advantages of low power consumption, low cost and high stability and it can be practically used in small power generation system.