Radial Force Characteristics of a Consequent-Pole Permanent Magnet Synchronous Motor

Consequent-pole permanent magnet synchronous motors (CPPMSMs) have only half the number of permanent magnets (PMs) of PMSMs, which can significantly reduce the usage of PMs. This paper analyzes the influence of the rotor core of CPPMSM on the armature reaction field and the influence of stator teeth on the magnet field based on flux-modulation effect firstly. Then the radial force characteristics of the CPPMSM are analyzed in detail from the perspective of field harmonics based on the Maxwell stress tensor method and verified by finite element analysis. The results show that the armature reaction field has more harmonics due to the modulation of the rotor core of CPPMSM, and the order of radial force of CPPMSM and PMSM under the same pole-slot combinations differs by an integer multiple of the number of pole pairs. When the number of pole pairs of the motor is an integer multiple of the greatest common divisor (GCD) of the number of poles and slots, the lowest order of the radial force of CPPMSM is consistent with PMSM, but its frequency is lower. While it is a fraction multiple, the lowest order of radial force of CPPMSM will become lower, and its frequency will also become lower. These radial forces with lower order or lower frequency should attract the attention of motor designers.