Analytical Modelling and Experiment of Novel Rotary Electro-Mechanical Converter with Negative Feedback Mechanism for 2D Valve

Abstract The manufacturing of spiral groove structure of two-dimensional valve (2D valve) feedback mechanism has shortcomings of both high cost and time-consuming. This paper presents a novel configuration of rotary electro-mechanical converter with negative feedback mechanism (REMC-NFM) in order to replace the feedback mechanism of spiral groove and thus reduce cost of valve manufacturing. In order to rapidly and quantitative evaluate the driving and feedback performance of the REMC-NFM, an analytical model taking leakage flux, edge effect and permeability nonlinearity into account is formulated based on the equivalent magnetic circuit approach. Then the model is properly simplified in order to obtain the optimal pitch angle. FEM simulation is used to study the influence of crucial parameters on the performance of REMC-NFM. A prototype of REMC-NFM is designed and machined, and an exclusive experimental platform is built. The torque-angle characteristics, torque-displacement characteristics, and magnetic flux density in the working air gap with different excitation currents are measured. The experimental results are in good agreement with the analytical and FEM simulated results, which verifies the correctness of the analytical model. For torque-angle characteristics, the overall torque increases with both current and rotation angle, which reaches about 0.48 N·m with 1.5 A and 1.5°. While for torque-displacement characteristics, the overall torque increases with current yet decrease with armature displacement due to the negative feedback mechanism, which is about 0.16 N·m with 1.5 A and 0.8 mm. Besides, experimental results of conventional torque motor are compared with counterparts of REMC-NFM in order to validate the simplified model. The research indicates that the REMC-NFM can be potentially used as the electro-mechanical converter for 2D valves in civil servo areas.