Effect of Stator and Rotor Pole Shapes on Torque of Flux-Modulating Consequent Pole Motors

The flux-modulating consequent pole motor (FCM) is a combination of a flux-modulating (FM) motor, which has flux regulation capability, and a permanent magnet (PM) motor. The FCM has a simple consequent pole rotor without brushes and slip rings, and a stator with concentrated armature and field windings. In this paper, the effect of stator and rotor pole shapes on the FCM’s torque is investigated. The torque is calculated from the Maxwell stress tensor method by separating the air gap magnetic flux density into space and time orders.

I. Introduction

PM motors are commonly used in applications requiring high torque and high efficiency. However, because the air gap flux produced by PM poles is fixed, a negative d-axis current must be injected during high-speed operation, resulting in increased copper and iron losses. We previously proposed an FCM that combines an FM motor [1] –[3] and a PM motor [4]. This FCM achieved a wider operating range and improved efficiency at higher speeds than conventional surface PM motors [5]. To improve FCM’s electromagnetic performance, we must know how the design parameters affect torque generation. In this paper, we calculate FCM’s torque by the Maxwell stress tensor method by separating the air gap magnetic flux density into space and time orders and discuss how the stator and rotor pole shapes affect the torque.