Research Of Integration Control Method Based On PLC And Variable Frequency Inverter And Its Application

Some technology and experience from the application of PLC and frequency variable inverter in practice are summed up in this thesis.Reliable design plan of PLC control system is presented.The frequency variable inverter technology and PLC control technology are discussed in detail.The performances of some PLC generally applied in our country are compared. For the programmable logic controller,the working principle,design method,reliability and the combination with frequency variable inverter are analyzed.The basic theory and method of automatic control of industrial field besed on the integration of PLC and frequency variable inverter are researched.The energy saving principle for the application of frequency variable inverter in the control of water pump is studied.Accoding to the functional requirement of water purification and transportation vehicle,a control system with the integration of PLC and frequency variable inverter is designed.Modeling work has been done for the constant pressure and constant flow control individually and control index analysis has been performed.Through above research work,design method and procedure of PLC and inverter applied in industrial field are put forward,in which the selction and design of hardware and software system,the integration of PLC and inverter,and speed adjusting method have important conference value in practice.Becase of the application of frequency variable speed adjusting technology in the control system of water purification and transportation,constant-flow closed loop control is realized successfully,and therefore the stability of waterflow is improved.A PLC module works as the core of the control system and the degree of automation and reliability of the whole system are impoved effectively.The starting power is reduced and the energy is saved. In Chapter 1,the development of control technology is discussed.In Chapter 2,the variable frequency speed adjusting technology is researched.In Chapter 3,the design of PLC system and the solution of some key problems are presented.In Chapter 4,the application of integration of PLC and inverter in the water purification and transportation vehicle is researched.At last,an application example is given and conclusions are obtained.