25-08-2017, 09:32 PM
Optimal Designs and Comparison of the Doubly
Salient Permanent Magnet Machine and
Flux-reversal Machine in Low-speed Applications
Abstract
The subject of this is to optimize the design and to compare
The performances of a low-speed doubly salient permanent magnet machine with
Those of a low-speed flux-reversal machine devoted to direct drive applications. The
Optimization, focused on the maximization of the machines mass-to-torque ratio,
is done by a genetic algorithm combined with the finite-element method (FEM).
The electromagnetic characteristics of the two optimized machines, including phase
Flux linkage, inductances, back-electromotive forces (EMFs), and static torque, ob-
Tainted from FEM analysis, are then analyzed and compared. Finally, the torque
Cost and the torque density of the two machines are compared with those of other
Topologies.
1. Introduction
For direct-drive low-speed applications, several machine topologies to fulfill the requirement
Of specific applications have been investigated and proposed [1“6]. The design of
These machines can be tackled through different approaches, including axial flux, radial
Flux, and even transverse flux types. The direct-drive benefits stand in the elimination
Of the gear and related problems (efficiency, oil maintenance and pollution, positioning
Precision
In various works on machines called doubly salient permanent magnet (DSPM)
Machines and flux-reversal machines (FRMs), it has been shown that by introducing
Permanent magnets (PMs) in the doubly salient structure of variable reluctance machines
(VRMs), new machine geometries can be realized [7“17]. These topologies appear to
Improve machine performances in terms of torque production.
The dented switched reluctance machine (SRM) with a great number of teeth and
The low-speed PM FRM type, which are illustrated in and described
In this, can be regarded as new members of the DSPM and FRM families,
Respectively they are the subjects for investigation Both machines have
Doubly salient structure and employ concentrated stator windings. Their field excitations
Are provided by non-rotating PMs located in the stator, and there is no magnet or winding
In the dented rotor Four pieces of PM are inset in the stator yoke of the DSPM machine,
While in the FRM, 8 PM pieces are mounted on the surface of each of the 12 stator
Plots facing the air gap In both machines, the magnets are magnetized in alternative
Opposite directions The machines are characterized by the same slot pitch, both on rotor
And stator teeth and the rectangular current shape is investigated. The shape of the rotor
And the stator teeth retained here is trapezoidal [2], while the shape of the PM retained
for the FRM structure is rectangular.
deals with the electromagnetic design and the optimization of this low speed
Machines with rated power of 10 kW at 50 rpm for direct-drive applications A
Comparison of the performances of the two optimized machines is then conducted.
The electromagnetic design optimization of these machines is done by genetic
Algorithms (GAs) combined with the finite-element method (FEM). The objective is
To maximize the mass-to-torque ratio that represents an essential feature of direct-drive
Applications
The optimization applies on the small teeth parameters as well as the global parameters,
Such as rotor and stator yoke, slot and magnet width, coil height, rotor radius,
And so on. To allow a good comparison between the two designed machines, identical
Architectures (the shape of the main elements) and identical optimization constraints are
Considered for both machines.
The electromagnetic characteristics of the two optimized machines, including phase
Flux linkage, inductances, back-electromotive forces (EMFs), and static torques, obtained
From FEM analysis, are then analyzed and compared. Furthermore, the comparison of the
Designed machines with other direct-drive structures, such as the SRMand transverse flux,
Axial flux, and radial flux permanent magnet (RFPM) machines is conducted. The results
Obtained show that the DSPM machine and the FRM structures studied and optimized in convenient for direct-drive applications.
Salient Permanent Magnet Machine and
Flux-reversal Machine in Low-speed Applications
Abstract
The subject of this is to optimize the design and to compare
The performances of a low-speed doubly salient permanent magnet machine with
Those of a low-speed flux-reversal machine devoted to direct drive applications. The
Optimization, focused on the maximization of the machines mass-to-torque ratio,
is done by a genetic algorithm combined with the finite-element method (FEM).
The electromagnetic characteristics of the two optimized machines, including phase
Flux linkage, inductances, back-electromotive forces (EMFs), and static torque, ob-
Tainted from FEM analysis, are then analyzed and compared. Finally, the torque
Cost and the torque density of the two machines are compared with those of other
Topologies.
1. Introduction
For direct-drive low-speed applications, several machine topologies to fulfill the requirement
Of specific applications have been investigated and proposed [1“6]. The design of
These machines can be tackled through different approaches, including axial flux, radial
Flux, and even transverse flux types. The direct-drive benefits stand in the elimination
Of the gear and related problems (efficiency, oil maintenance and pollution, positioning
Precision
In various works on machines called doubly salient permanent magnet (DSPM)
Machines and flux-reversal machines (FRMs), it has been shown that by introducing
Permanent magnets (PMs) in the doubly salient structure of variable reluctance machines
(VRMs), new machine geometries can be realized [7“17]. These topologies appear to
Improve machine performances in terms of torque production.
The dented switched reluctance machine (SRM) with a great number of teeth and
The low-speed PM FRM type, which are illustrated in and described
In this, can be regarded as new members of the DSPM and FRM families,
Respectively they are the subjects for investigation Both machines have
Doubly salient structure and employ concentrated stator windings. Their field excitations
Are provided by non-rotating PMs located in the stator, and there is no magnet or winding
In the dented rotor Four pieces of PM are inset in the stator yoke of the DSPM machine,
While in the FRM, 8 PM pieces are mounted on the surface of each of the 12 stator
Plots facing the air gap In both machines, the magnets are magnetized in alternative
Opposite directions The machines are characterized by the same slot pitch, both on rotor
And stator teeth and the rectangular current shape is investigated. The shape of the rotor
And the stator teeth retained here is trapezoidal [2], while the shape of the PM retained
for the FRM structure is rectangular.
deals with the electromagnetic design and the optimization of this low speed
Machines with rated power of 10 kW at 50 rpm for direct-drive applications A
Comparison of the performances of the two optimized machines is then conducted.
The electromagnetic design optimization of these machines is done by genetic
Algorithms (GAs) combined with the finite-element method (FEM). The objective is
To maximize the mass-to-torque ratio that represents an essential feature of direct-drive
Applications
The optimization applies on the small teeth parameters as well as the global parameters,
Such as rotor and stator yoke, slot and magnet width, coil height, rotor radius,
And so on. To allow a good comparison between the two designed machines, identical
Architectures (the shape of the main elements) and identical optimization constraints are
Considered for both machines.
The electromagnetic characteristics of the two optimized machines, including phase
Flux linkage, inductances, back-electromotive forces (EMFs), and static torques, obtained
From FEM analysis, are then analyzed and compared. Furthermore, the comparison of the
Designed machines with other direct-drive structures, such as the SRMand transverse flux,
Axial flux, and radial flux permanent magnet (RFPM) machines is conducted. The results
Obtained show that the DSPM machine and the FRM structures studied and optimized in convenient for direct-drive applications.