Systems that make use of electronic sensors in rotating parts are becoming increasingly popular. This implies making electrical connections between stationary and rotating parts. Traditionally, slip rings are used for this purpose. These components however come with a number of disadvantages: Poor signal integrity, the need for a large number of slip ring channels (and hence large volume) for transferring many measurement channels, frequent need for maintenance because of contact wear, and the fact that slip rings are unsuitable at high rotational speed. All these aspects play a role in certain scale models that are used in wind tunnel experiments.
As a part of a sophisticated wind tunnel model, NLR developed a contactless transfer system, for which a patent has been granted in Europe, the United States and Canada. The transfer system provides electrical power of a few tens of Watts on the rotor. Apart from this, a bi-directional data link is available which allows reliable data exchange up to 1 Gbit/s. In the wind tunnel model, the data link is used to report measurement data of dozens of wideband measurement channels. Electrical power is transferred magnetically, while the data link is established through near-field communication.
Through its design, the patented system is particularly suited to systems rotating at high speed. In wind tunnel models it is not uncommon to encounter centrifugal acceleration in excess of 20,000 g.
Applications for the technology described in the patent “Contactless power and data transfer” go further than just wind tunnel models: All systems that require wear-free data or power transfer between a stator and a rotor qualify, even if the stroke is less than a full revolution. Apart from the scientific domain, typical applications are for robotic arms, aircraft propellers, ship’s screws, etc.
US Pat. No. 9,812,255; CND Pat. No. 2,879,466
Espacenet registration: Contactless power and data transfer