Axial Field Permanent Magnet DC Motor With Powder Iron Armature

The paper describes a double-gap axial field permanent magnet (PM) dc motor whose double-layer armature wave winding is constructed of copper strips. It investigates the performance of two machines using powder iron and lamination steel materials as armature teeth. Tests are conducted to evaluate the motor torque and speed curves as well as their efficiency under different loads. Finite element analysis (FEA) and equivalent circuit models are used to determine the levels of the magnetic saturation in the motors; calculate torque, inductance, and electromotive force (EMF); and determine the distribution of losses in the machine. The results show that the powder iron armature machine has lower back EMF and torque constants, and is less efficient than the steel laminations machine, which is due to the lower permeability and saturation flux density of the powder iron material.