Consequent-pole permanent-magnet machine with extended field-weakening capability

Abstract

In this paper a description and operating principles of a consequent-pole permanent-magnet machine are presented. In addition, a sizing analysis, finite-element analysis, and experimental results for a prototype machine are addressed. Due to its particular configuration, this machine allows for a wide range of control of the air-gap flux with minimum field ampere-turn requirements and without brushes or slip rings. Two components of the field flux are produced. One, which is almost constant, is produced by the permanent magnet located on the rotor surface. The other, which is variable, is produced by a field winding positioned circumferentially in the center of the stator. These two flux components converge in the air gap. The excitation level of the machine is manipulated by controlling the dc field current. Three-dimensional finite-element analysis and experimental results demonstrate that it is possible to vary the flux over a wide range to keep the terminal voltage constant as the speed increases. A 3-kW 1000-3000-r/min eight-pole and 32-Vac generator using this configuration is tested to verify the flux control capability of this structure.

Electromagnetic Performance Analysis of Novel Flux-Regulatable Permanent Magnet Machines for Wide Constant-Power Speed Range Operation

“…Energies 2015, 8,[13971][13972][13973][13974][13975][13976][13977][13978][13979][13980][13981][13982][13983][13984] where Φ PM1 is the flux linkage excited by the inner rotor PMs and Φ PM2 is the flux linkage excited by the middle rotor PMs. To achieve preferable field control capability, hybrid excitation structure is shown in Figure 3c.…”

“…However, the shortcoming of this design is its relatively high cogging torque. Several other hybrid excitation synchronous machines have been proposed [4][5][6][7][8]. Based on the former study, generally, the hybrid excitation machines is divided into two different types: series hybrid excitation machines and parallel hybrid excitation machines.…”

Magnetic equivalent circuit model for unipolar hybrid excitation synchronous machine

“…In the bipolar system, the electromagnetic excitation flux influences both pole zones of the machine, and in the unipolar system -only the zone of like poles. In this article, authors consider the construction of an unipolar hybrid excitation synchronous machine presented in figure 1 [7]. It is composed of a rotor with two segments (3 and 4) and two stator stacks (7) connected with an external yoke (10) made of ferromagnetic material, which constitutes the frame, and with an internal yoke in the form of a sleeve (2) and shaft (1) made of ferromagnetic material.…”

“…The constructions of hybrid excitation synchronous machines has been under consideration for many years [3][4][5][7][8][9][10][11][12][13]. Previously, the main objective of constructing such machines was to assure stabilization of voltage in generating mode during operation under variable loads and speeds with non-slip-ring rotor construction or self-exciting generators with the rectifier in the field winding supply circuit, operating autonomously [3,5].…”

“…This machine is also known in the literature of the subject as consequent pole permanent magnet machine [7] or inductor generator with combined excitation [5].…”