Wireless Power Supply of Moving Linear Actuator Enclosed in Stainless-Steel

Linear actuators are a key element of automatized industrial systems, as linear motion is present in most manipulation tasks. For actuators performing x-z movements, actuator windings are placed on the moving part and these must be supplied. However, in high-purity environments such as in the food processing or pharmaceutical industries, actuators should be fully enclosed in stainless steel (SS) to facilitate thorough cleaning, and cables are undesirable. This paper therefore proposes high-efficiency (97% at 100W) wireless power transfer (WPT) through two 0.5mm thick SS enclosures, which facilitates the deployment of linear actuators in high-purity environments. The proposed coaxial transformer arrangement with the magnetic core mounted on the moving part results in a magnetic field that is in parallel to the SS enclosures, which minimizes eddy-current losses. We discuss the detailed modeling and optimization of the system, and finally present an industrial two-axis actuator prototype that fully confirms the theoretical analysis.