Induction Heating of Motor Stator Core Using a Magnetically Closed-Loop

Self-bonding coated electrical steel sheets enable the laminations to be bonded through induction heating and pressure curing without the use of mechanical interlocks, thereby avoiding magnetic property degradation caused by stress concentration and plastic deformation associated with conventional interlocking processes. This paper presents an inductive heating method based on a magnetically closed-loop, intended for ring-shaped electrically conductive structures such as motor stator cores. The eddy-current-induced ohmic heating process can be modeled as a transformer with a short-circuited secondary winding. Compared with conventional open-loop induction heating configurations, the proposed closed-loop method exhibits superior performance in terms of magnetic flux coupling, dimensional tolerance, and effective heating power. Experimental measurements were conducted to validate these advantages. In addition, a partial differential equation (PDE)-based electromagnetic field analysis was performed to characterize the current density distribution along the radial direction of the ring core.