Brushless Wound Field Synchronous Generator Design With an Optical Power Transfer

Rare-earth permanent magnet-based generators offer high power density, but face challenges due to their inability to deactivate the magnetic field during failures. Wound field synchronous generators (WFSGs) have gained attention as a solution to these issues, but mechanical brushes negatively impact reliability. To address this, wireless power transfer (WPT)-based WFSGs have been proposed for their enhanced reliability, though they require low airgap passive components that hinder high-speed operation. This paper presents the design and optimization of optical power transfer (OPT)-based WFSGs using PV cell excitation. The design constraints were calculated considering PV cell characteristics at maximum power point (MPP), and a finite element analysis (FEA) was conducted to analyze the characteristics of the OPT-based WFSG. Three cases were analyzed: constant optical power, constant output power, and high-speed operation. The optimal WFSG designs for efficiency and power density are identified by analyzing core and copper losses, which are calculated based on the WFSG designs and their respective design constraints. Furthermore, a feasibility study on high-speed operation explores the relationship between optical power and speed for maintaining consistent output power.