A brief discussion on the design of solar power generation system control panel

　　In recent years, as people pay more attention to environmental issues, the earth's demand for clean energy has become higher and higher. Our company has been committed to the research and development of power conditioning systems (PCS) for solar power generation.

　　Combining the research and development case of the solar power generation system control panel, this article introduces the methods of reducing costs and increasing the number of parallel connections to adjust the system of multiple solar panels.

　　1 System Overview

　　FIG1 is a block diagram of a large-scale solar power generation system.

　　The characteristic of this system is that the solar panels and unit inverters are connected to the system in groups (AC connection), and the information such as system protection is summarized and sent as a signal to the main controller, and then the controller controls each unit inverter (connected to the daisy chain through RS485 communication).

　　The control part of each unit inverter is shown in Figure 2.

　　By using our company's standard DSP substrate (PE-PR0/C32), MPPT control and system integration of the above specifications can be achieved. After adding communication and other functions to the substrate, the control board part shown in Figure 2 is formed. The power supply part is designed and produced by the end user. The main circuit is shown in Figure 3.

　　2 R&D Cases

　　When the design was carried out, it was developed based on the company's standard product DSP substrate. Therefore, it took only 3 months to develop the sample machine, which greatly shortened the development time and quickly entered the testing stage (PE-PR0/C32: DSP uses TI's high-speed floating-point DSP TMS320C32).

　　At the same time, in order to reduce sales costs, we designed and developed a new control board using Renesas' RISC CPU SH7065 (fixed decimal point type). By using the RISC CPU, expensive components such as A/D converters can be reduced in configuration, making switching smoother.

　　Based on our development system, when the core chip is changed from DSP (TMS320C32) to RISC CPU (SH7065), there is no need to modify the program significantly due to factors such as electric pulse counting. This is because it uses a unique analog floating decimal point, making it easy to transfer programs between fixed decimal points and floating decimal points. All of this can be achieved through our standard library (PEOS).

　　3 Conclusion

　　So far, more than 300 units of the unit inverter control board have been sold in Japan, and production is still ongoing. Through our company's development system, we believe that we can fully assist users in shortening the development time, achieving mass production as soon as possible, and improving product quality during product development.