Research On Mixed-Excitation Electromagnetic Actuator And Its Control System

Electromagnetic actuators are widely applied in the fields of civilian and military industry, aviation and aerospace etc. With the development of application technology, electromagnetic actuator is required to be miniaturized, fast and high precise controlled, or to realize close-loop control with feedback of some parameters which users are interested in. For example, in the application of multi-fingered or apery robot hand, small size, high output force and fast precise position control are needed. For solenoid valves applied in fluid control field, it is necessary to realize proportional or servo control of press, flux or speed parameters. On this background, the investigation of mixed-excitation electromagnetic actuator and control system are put forward in the paper.Firstly, the paper has reviewed the domestic and foreign development of electromagnetic actuator and its control techniques, and pointed out the problems and hot issues. The paper has discussed the related theory including the working characteristic of permanent magnetic, servo control techniques and techniques of electropneumatic proportional and servo valves. Then after the analysis of direct action solenoid valve with permanent magnetic and electromagnetic force, hydrokinetic force and resistance, the motion equation of the spool is deduced, and the proportional control is brought forward. Then a novel linear electromagnetic actuator system for position servo applications is described. The actuator is made of an NdFeB permanent magnetic moving part, which can return to equilibrium point and have hold force during the excitation power off, a stator with double excitation coils and two operating gaps. By changing the combination of the two electromagnetic excitations, the actuator can run in four quadrants of acceleration or braking in duel direction. Changing the coil current can regulate the acceleration/deceleration and the hold force. Also the magnetic field distribution of the actuator is calculated using finite element analysis. Also the position control system of the actuator is developed. Its controller is based on a single chip processor with high accurate A/D converter to realize position information conversion. The electromagnetic excitation can be regulated by PWM driving module. The LED display and keyboard input modules are also...