A reciprocating permanent magnetic actuator for driving magnetic micro robots in fluids

Magnetic-based driving applications are receiving increasing attention. This study proposed a novel reciprocating permanent magnetic actuator (PMA) to manipulate magnetic micro robots to impact and clear blockages inside fluid pipes in a linear path. The PMA consisted of a cylindrical permanent magnet and a crank slider structure. A straight pipe with a circular cross-sectional area was located in front of the actuator to study the driving performance of PMA. A micro permanent magnet with a cylinder shape was employed as a working robot for manipulation inside the pipe. Firstly, analytical formulas were derived to obtain the magnetic driving force acting on the micro robot and determine the most suitable magnet configuration. The finite element simulation verified the analytical calculation. The developed reciprocating PMA prototype was then introduced, and the PMA and micro robot’s motion performance was analysed. Lastly, preliminary experiments were carried out for evaluating the micro robot’s motion characteristics. Performance tests for different excitation frequencies, flow rates, viscosities, and axial distances, indicating that PMA could manipulate the magnetic micro robot inside the pipe. The results confirmed that the developed PMA could effectively drive the micro robot with the advantage of consecutive magnetic driving. Especially, the micro robot featured good flexibility, rapid response, and a simple structure, suggesting that this micro robot may play an important role in industrial and medical applications, such as blockage elimination and thrombus clearance.

Design and Realization of Intelligent Phase-controlled System for Permanent Magnetic Actuator of AC Contactor

When the AC contactor switches the capacitor bank, the phase angle of the power grid is random, so the electromagnetic transient process will generate large inrush current and overvoltage, causing large disturbance to the power system. A set of AC contactor with permanent magnetic actuator (PMA) and its intelligent phase selection control system are designed to solve this problem. Firstly, the PMA is designed. The dynamic characteristics of the actuator are simulated and analyzed in ANSOFT to meet the performance requirements of phase selection control. Then the principle of phase selection control and the strategy of switching capacitor bank are analyzed. Based on this, the software and hardware of intelligent phase selection control system are designed, including phase selection control module, IGBT driver module and coil discharge module. Finally, the experimental verification is carried out on the designed AC contactor. The test results show that the phase selection errors of the designed intelligence system are within 1°, and the contactor closing and opening time deviations are within 0.5ms, which means the system can effectively realize the closing and opening control at the specified phase angle.