Investigation of Flux-Modulating Consequent Pole Motors

This article investigates the electromagnetic performance of a novel variable-flux permanent magnet (PM) motor, named the “flux-modulating consequent pole motor (FCM),” through finite element analysis (FEA) and experiments. The FCM is a combination of a flux-modulating (FM) motor and a consequent-pole PM motor, whose torque can be generated from both the FM and PM motors without causing unbalanced magnetic forces (UMFs). Two models with 16 and 20 poles are used to analyze the torque, efficiency, and power factor of the FCM. Moreover, efficiency maps of the FCM are compared with those of the conventional PM synchronous motors. It is revealed that the torque of the FCM depends on the values of winding factors of the FM and PM motors. Finally, experimental results on a 20-pole prototype machine are presented to validate the operating principle of the FCM and the FEA simulations.

I. Introduction

Permanent magnet (PM) motors have been widely used for applications that require high torque and high power. However, because a negative -axis current injection is employed to achieve high-speed operation, copper and iron losses increase [1], [2]. To address these issues, we proposed a novel flux-modulating consequent pole motor (FCM) that is a combination of a flux-modulating (FM) motor [3], [4], [5] and a consequent-pole PM motor [6], [7] in a previous study [8]. In the FM motor, a three-phase armature winding () and a field winding () are centrally wound around individual stator teeth, and the flux linkage of can be adjusted by changing the field current supplied to . In the consequent-pole PM motor, the rotor consists of PM poles and iron poles, and the number of PMs can be reduced.