Vibration Reduction Design of Consequent Pole PM Machine by Symmetrizing Local and Global Magnetic Field

The consequent pole permanent magnet (CPM) machine is well known for its high magnet utilization ratio and poor vibration performance. This article focuses on electromagnetic vibration and its reduction design in CPM machines, and the conventional surface-mounted permanent magnet (SPM) machine is used as a benchmark. First, the asymmetrical magnetic field and unbalanced radial force of the CPM machine are investigated with emphasis. The slot-pole combination and force modulation effect are the two reasons for the unbalanced radial force generation. Afterward, two new designs to reduce the vibration caused by the unbalanced radial force are proposed, and the reduction principles are described in detail. Finally, the prototypes of the 12-slot/10-pole SPM and proposed CPM machines are manufactured. The tests are conducted to validate the theoretical analysis and proposed vibration reduction design.