Desigen And Implementation Of The Electric Actuator With Variable Frequency Speed Control

The electric actuator takes the electrical energy as power, accepts standard signal (simulation quantity or digital quantity) which comes from the regulator, by changing these signals into the corresponding mechanical displacement to change the operation wariable automatically, in order to regulate the parameter referenced automatically, and causes the production process to carry on according to predetermined request.In the nuclear power, metallurgy, petroleum, chemical, power, water and large-scale coal-chemical industry actuator is playing an increasingly important role in the process automation control. Therefore, its reliability, security, and real time requirements are higher and higher. Foreign companies started earlier than ours, technological monopoly, dominating the majority of intelligent electric actuators market in China. Domestic research on the actuator was behind the foreign. So it is important to develop independent intellectual property rights, breaking the monopoly of foreign-made intelligent technology electric actuator.The article discusses the current domestic and foreign electric actuator research and development. According to the characteristics of today’s popular electric actuator, the subject designs an electric actuator with variable frequency speed control. The system uses Freescale’s16-bit microcontroller as the system overall scheduling. The power circuit uses AC-DC-AC converter structure which uses PIM that has high switching speed and is suitable for small power devices as inverter device. IR2233driver chip which is connected with the PIM’s output drives three-phase AC induction motor, its working voltage is up to1200V. The PWM control signals from the inverter are produced by the three-phase induction motor control chip MC3PHAC. This reduces the burden on the microcontroller and makes the design more modular. The actual working atmosphere needs that real-time detection and display of the valve opening continues when the system is power-down. So, in order to ensure detection of valve position uninterrupted, system switches power supply and battery powered to each other, battery supplies power when system have no external power supply.Because the VVVF control technology may lead motor to fault in the low speed high torque case. Therefore, this article will use complex indirect field oriented control (IFOC) algorithm to compensate for shortage of VVVF control. The algorithm involves the coordinate transformation and inverse transform, PI regulator, speed and position estimation and SVPWM. This case’s software design is difficult, but it simplifies hardware design and solves the problem when motor works in a low speed and large torque case. By establishing the control model on PSIM, we verify its feasibility. The indirect field oriented control algorithm will be applied to a hardware platform whose control core is ARM CortexM3.