An Interleaved U-Shaped Core Rotary Transformer With High Multidirectional Misalignment Tolerance for Rotary Wireless Power Transfer

In terms of energy supply for rotating equipment, rotary wireless power transfer (RWPT) has gradually become prevalent, replacing the traditional brush and slip ring system due to its high reliability and high efficiency. The misalignment tolerance (MT) of the rotary transformer (RT) directly affects the output stability and efficiency. To address this issue, this article proposes an interleaved U-shaped core rotary transformer (IUCRT), which not only has the same level of mutual inductance, manufacturability, and cost as the traditional aligned U-shaped core rotary transformer (AUCRT), but also exhibits high multidirectional MT. First, the reluctance model of the proposed IUCRT is established, and its impact on the system stability is analyzed theoretically. Subsequently, parameter analysis and optimization design are executed to improve its multidirectional MT. Finally, a 900 W prototype was developed, and the experimental results show that the dc-dc efficiency maintains exceeding 90% from 300 to 900 W. Synchronously, under the condition of a maximum 12 mm radial misalignment, arbitrary rotating misalignment, or 4.5° capsizal misalignment, the prototype can not only maintain exceeding 91% of the output voltage compared with that under the aligned state but also maintain exceeding 90% of the total efficiency. Especially, as the X-misalignment is smaller than 10 mm, the system can achieve a high-efficiency output exceeding 96% of the rated voltage.