Design Of Control System For Electric Actuators

Intelligent electric actuator, the core element of the producing process in the industrial automation, plays an important role in the industrial automation and control system. However, the control system, as the central part of the electric actuator, plays a decisive role in the electric actuators intelligence and reliability level.In this paper, the intelligent control system of the switch type electric actuators is our research object. The design of the electric actuators meeting requirements is proposed. In terms of reliability and intelligence, four optimizations are proposed. We conclude them as follows.(1)Electric actuators generally operate in a complex electromagnetic interference environments, which will result in a strong impact on the main chip. In the most existing control systems, 2~3 microprocessors are used for displaying, acquiring data, driving motors respectively and RS232 or RS485 interface are used to communicate serially among the processors. Decreasing the number of microprocessors can reduce electronic interference on the system. In this paper, only one microprocessor is used to complete all the tasks, increasing the reliability of the system.(2)The control system of the electric actuators has the function of correcting phase sequence automatically, realized by discrete components in most references, using phase difference method to identify three-phase power phase sequence and to detect lost phase. With small size, low power consumption, high input impedance, less external components, high integration, this paper uses an integrated chip-DF783A-as the core. Compared with the circuit realized by discrete components, it achieves higher reliability.(3)In the process of hardware design, we prefer to select the industrial grade integrated chips. And in the process of PCB layout, components are preferred to be placed on the top of the board. Meanwhile the control system is fixed in the electric actuator we place the board back to the motor and add an aluminum plate for isolation between the control system and the motor, preventing the effects of electromagnetic interference effectively.(4)In terms of intelligence, especially in the control strategy, the control system acquire, filter, recognize input data, blends control algorithm to process input data and outputs control signal and indication signal. The control system prior to protect motor, supplemented by self-diagnosis and real-time alerting, shielding erroneous input signal, stroke sensor zero-crossing detection and motor instantaneous reversal protection.Based on the four points, the hardware is designed according to demand analysis of electric actuators. According the real-time performance and using foreground/background system frame and MSP430 assembly language, the software of the system is compiled. By allocating the microprocessor resources reasonably, coordinating hardware modules and playing the optimal performance, an intelligent control system integrating with interactive interface, field control, remote control, Modbus control, remote contact signal output and non-invasive signal input functions is designed. A test is carried out to prove that the system has a good performance of high stability and reliability.