Investigation on flat torque‐angle characteristic of torque motor based on magnetic saturation of tooth tip

The flat torque-angle characteristic of torque motor plays a decisive role in the control quality of electro-hydraulic servo and proportional valve. To solve the issue that the current wet-type torque motor for two-dimensional (2D) valve does not have flat torque-angle characteristic, a method for adjusting the flat torque-angle characteristic of torque motor for 2D valve based on magnetic saturation of tooth tip is proposed. Taking the current limited angle torque motor with rectangular tooth (TM-R) as an application example, the rectangular teeth on the stator are replaced by sharp teeth to form a novel torque motor with sharp tooth (TM-S), and the flat torque-angle characteristic can be obtained by constructing magnetic saturation of tooth tip. The variation trends of magnetic permeance in each magnetic saturation region of the tooth tip are analyzed. The torque-angle characteristics of TM-S and TM-R under different control currents are compared. Prototypes of TM-S and TM-R with optimized parameters are designed and manufactured, and special experimental benches are built for static and dynamic test. Experimental results are basically consistent with the theoretical analysis. The comparative study shows that the torque-angle characteristic of TM-R is a downward curve, while the torque-angle characteristic of TM-S is an approximate flat curve. The research validates the effectiveness of the proposed method, which can both realize the flat torque-angle characteristic and improve the dynamic response of torque motor. Finally, the proposed method can be further applied to other rotary and direct-acting electro-mechanical converter (EMC) with multi-tooth structure.