Research Of Monitoring And Communication System For Cascaded Multilevel Inverters

With the development of the inverter technique and the market demand of saving energy source, reducing the wastage and improving the economic benefit,the inverter technique will be developed toward the higher voltage, the bigger power and superior performance.Presently, in both here and abroad, the high-voltage inverter products mostly support the standard serial communication,also, they need communicate with other monitoring control system more and more in the application field.The human-machine interface software on industrial control system is mostly the general configuration software,which has some limitation at the special field.Based on the reasons mentioned above, the monitoring and communication system for cascaded multilevel inverter are selected to be studied in this thesis. The main contents are following:(1) The whole scheme of the communication and monitoring system was designed.(2)The hardware circuit of the inverter's output current, output voltage and voltage was worked out, as well as the sensor output signal's amplifying, conditioning, sampling.(3)Labwindows/CVI provided by NI is applied to design the friendly human-machine interface, which can display the actual frequency, output voltage and current by real-time, reinforcing the operationality of the equipment and improving the working efficiency.(4) Labwindows/CVI is applied to design serial communication based on the RS232 bus between TMS320LF2407A and PC, including hardware interface circuit and software program.In this paper, the software frame based on the inverter system was designed, including the control, communication, display, numerical analysis, appling multithreading and modularization on Windows platform and virtual instrument technology.Above speaking, along with the development on network technique and field bus,the demand of inverters towarding the informatization and network must be paid high attentioned.Many functions must be actualized, including the remote monitoring, controlling,diagnosising,testing and setting for the inverter,to adapt the demand of industrial field bus technique,the more challenges will be faced in the future.