Scaled rotatory transformer models, design and control

This report presents the design of a rotary transformer configuration (i.e. a wireless power transfer system) capable to handle the MW power transfer requirement of the XROTOR system. The deliverable includes a detailed specification of the rotatory transformer including parameters such as operating frequencies, current density, windings area, air-gap length, and others. The efficiency is quantified using finite element simulation and numerical calculations. Furthermore, its thermal performance at rated power levels is analysed and quantified using finite element simulation. The simulation results show that high level of efficiency (around 98.5%) can be obtained with a proper design methodology and suitable compensation network for the transformer system.

The second section of the report provides the design and analysis of a suitable power electronic topology for the rotary transformer to manipulate the wireless power flow at the levels of efficiency required by the XROTOR project. The analysis includes electrical operation and energy conversion losses simulation of a three-phase dual active bridge configuration suitable for high-power wireless power applications. The simulation demonstrates the suitability of the topology to drive MW level power through a rotary transformer system at efficiencies of around 98%. This efficiency is calculated via electrical and thermal analysis and simulations.

Results indicate that the combined efficiency of the rotary transformer with its associated power electronic converter turned to be 96.53% for a 1MW system.

The methodologies presented in this deliverable can be utilized to design multi-MW level rotary transformer system and associated power electronic drivers. The designed parameters utilize the standard DC voltage levels of commercial back-to-Back converter for wind generators. As such, the designs presented in this report can be incorporated as another energy conversion stage in the DC bus of a commercial Back-to-Back power electronic system.