LL‐delta structure for CS featuring high‐PTC

Abstract

Aiming to improve the power transfer capability and efficiency of contactless sliprings (CS), LL-delta structure for rotary transformer is proposed. Compared with the conventional UU structure, the effective cross-section of magnetizing flux for LL structures are increased, resulting in higher coupling coefficient (k), mutual inductance (M) and associated improved power transfer capability and efficiency, without the burden of size. The finite element analysis is performed and demonstrates that the power transfer capability of the proposed LL-delta structure is about 1.88–5.76 times larger than that of UU structure, and about 1.55–1.61 times larger than that of LL-basic structure. Three rotary transformers with UU, LL-basic and LL-delta structure are fabricated along with the comparative experiments. Measured results indicate that the proposed LL-delta structure has the largest product kM. With the same exciting current and the load quality factor, 2.06 kW output power is picked up for CS with LL-delta structure, whereas 1.08 kW for UU structure and 1.36 kW for LL-basic structure. The maximum efficiency for CS with LL-delta structure is 96.97%, which is about 0.7% higher than that of UU and LL-basic structures. The simulation and experimental results verify the effectiveness of the proposed structure.