Research And Design Of Intelligent Electric Actuators With Variable Frequency Control

Electric actuator is widely used in process control of power plant,petrochemical,municipal,nuclear power,metallurgy,water conservancy and coal chemical industry,and plays an important role.Electric actuator is an important executive unit in industrial control system,which converts electric energy into mechanical displacement or rotation angle.The working process is to accept remote or local control commands(switch quantity,analog quantity or digital quantity).Through the analysis of the instruction,the motor is driven according to the instruction to drive the mechanical components to realize displacement or angle change,In order to achieve the purpose of industrial control system to operate or adjust the electric actuator automatically.With the development of automation,information technology and reliability technology,the user has higher and higher requirements for intelligent,energy saving,reliability and safety of electric actuator.Therefore,it is of great significance to develop intelligent frequency conversion electric actuator to occupy the high-end market in China.This paper designs an intelligent variable frequency electric actuator based on the characteristics of the mechanical part of the electric actuator.The valve motor of the system is driven by SPWM Frequency converter,and the main controller is controlled by 32 bit arm of Italian semiconductor.The system adopts frequency conversion drive technology to realize the valve slow opening and closing to avoid hammer effect.The on-line detection technology is used to detect the torque and stroke in real time,and the precise control and protection of the valve can be realized.The fault diagnosis and early warning are carried out in the operation process by using the fault diagnosis technology.SPI bus interface and bus board mode are used to realize various bus communication.The application of static flash stack technology can realize the online program overload(IAP).The system uses multi circle absolute position encoder to detect the travel of electric actuator on line.Through NS main cycle and valve position adaptive control method,the precise position control and power off valve position are not lost when the high speed is high.The full stroke precision measurement of valve torque is carried out by using tension sensor,and the percentage of torque is displayed by OLED.The SPI interface is designed to realize the communication of modbus,Hart,PROFIBUS,FF and other fieldbus.The big data storage model is designed,and the life cycle data of electric actuator is recorded in RAM on board.The remote online program is overloaded by bootloader and user application.The system also has intelligent interfaces such as gravity sensor,USB interface and Ethernet interface to meet the needs of Internet of things.After the design of hardware and software,the function module test is carried out;The basic performance,EMC test and long-term stability test verify the whole system function and performance.