Hybrid excited linear actuator for direct drive valves.

Moving-iron electromagnetic actuators have been widely used in industry. But the properties are conflict in high levels of linear force, long stroke, low power consumption and high force/volume ratio. A hybrid excited linear actuator (HELA) was proposed to provide an innovative high-performance solution for direct drive valves. The characteristics of static electromagnetic force were optimized and analyzed. Meanwhile, dynamic performance was simulated by 3D finite element method taking into account the eddy current loss of materials. The simulation results agree well with the experiments. And the results show that the prototype's magnetic paths distribution is regulated by the structural parameters, which leads a linear output force within a stroke of ± 3 mm. Besides, the prototype's force/volume ratio is up to 4.5 × 107 N/m3. The holding force at the ends of stroke is more than 120 N. Therefore the holding current is eliminated, which reduces the power consumption effectively. Furthermore, the prototype's time of step voltage response is 4.3 ms and frequency response (-3 dB) of the displacement reaches about 60 Hz. Additionally, the eddy current is a significant factor affecting the dynamic performance, which increases more than 8 percent in the step voltage response time. [ABSTRACT FROM AUTHOR]