Torque and losses in the metallic shell of a dual mechanical port PM electrical machine, for dangerous fluid pumps

The paper develops an analytical evaluation of the torque and of the losses in a metallic shell, used as separator and/or retaining cup of Permanent Magnets (PM) in Dual Mechanical Port Machines (DMPM) for pump drives. The DMPM disposition assures a mechanical driving back up in case of electrical failure; moreover, the adoption of a separator allows to avoid the use of stuffing boxes, reducing the risk of loss of dangerous fluids in the hydraulic circuit. Some FEM simulations confirm the theoretical results, and validate the analytical approach.