Proposal for Suppressing the Influence of Rotary Transformer’s Leakage Flux on the Accuracy of Wound-Rotor Synchro

Synchros are electromagnetic position sensors extensively employed in industrial applications, with the Wound-Rotor (WR) type being the most common. However, the leakage flux of the Rotary Transformer (RT) used to excite WR synchros can adversely affect the output signals and reduce sensor accuracy. To address this issue, this paper investigates the influence of RT leakage flux on the performance of WR synchros. Several approaches are explored to mitigate these effects, including the use of electromagnetic interference (EMI) shielding materials, whose impact on synchro accuracy is analyzed. In addition, a novel RT configuration is proposed to further minimize leakage flux, thereby improving accuracy compared to the conventional design. The proposed RT structure also offers advantages in terms of reduced weight, improved heat dissipation, and lower voltage total harmonic distortion (THD). To evaluate and optimize the proposed design, a Magnetic Equivalent Circuit (MEC) model is developed. The effectiveness of the approach is validated through 3-D Time-Stepping Finite Element Analysis (TSFEA), followed by the construction and experimental testing of a prototype. The experimental results show good agreement with the 3-D TSFEA predictions, confirming both the accuracy of the developed model and the validity of the proposed methods.