Characteristics of an axial-flux permanent magnet synchronous machine with contra-rotating rotors under unbalanced load condition from 3-D finite element analysis

Abstract

During recent years, the axial-flus PMSM with contra-rotating rotors has become a hot topic in academic research due to its high efficiency and simple structure. However, its back-EMF may be distorted under the condition of different angular positions. This paper investigates characteristics of the novel motor used for contra-propeller driving. Considering the torque ripple and current oscillation under unbalanced load condition, this paper analyzes the distorted back-EMF of the machine when its two rotors get different angular positions during rotating. The analysis results are validated by transient-magnetic 3-D FEA method, which the 3-D FEA software is used to model this motor and transient simulations are carried out to obtain its magnetic characteristic and main performances. A main focus is put on the back-EMF characteristic with different angular positions between the two rotors. Furthermore, the characteristic of torque production under unbalanced load is investigated. Finally, a prototype motor is fabricated to validate the analyses of this paper. Index Terms-3-D finite element analysis (FEM), back electromagnetic force (back-EMF), contra-rotating rotors, permanent magnet machines. I. INTRODUCTIONONTRA-ROTATING propellers (CRP) comprise two propellers settled coaxially and operated in an opposite direction. When used for ship propulsion, the CRP can recover energy from the circumferential flow of its main propeller. It has been demonstrated that the efficiency of the system can be raised up 15% [1] when a CRP is installed. Moreover, the CRP

Review of Design and Control Optimization of Axial Flux PMSM in Renewable-energy Applications

“…The opposite windings on the two sides of the stator core are connected at the ends of the windings, as shown by the dashed lines, to form various toroidal windings. The only difference between Figure 8(a) and (b) is that the magnetic fields on the two sides of the stator core rotate in the same direction in the winding structure shown in the latter [31].…”

“…The key aspect of motor design is electromagnetic performance design. The most commonly used methods include the size equation [11,31,36,37], finite element analysis (FEA) [31,38,39], equivalent magnetic circuit [40,41], and analytical calculation methods [42,43]. The improvements in motor-design methods are essential for motor optimization, and many studies have focused on broader prospects of optimization.…”

An analytical formula for back EMF waveform of a counter‐rotating dual‐rotor non‐slotted axial flux permanent magnet synchronous machine

“…In CRDRAFPM, to produce two fields with different directions, a special arrangement of windings is used. This arrangement of windings is either based on the shifted winding [9,10] or the independent winding model [11]. Distributed winding and concentrated winding are two common types of windings that have been used in PM machines.…”

Comparative Research on Topologies of Contra-Rotating Motors for Underwater Vehicles

“…The windings on both sides of this prototype are connected in series, so the armature windings on both sides will be crossed so that the phase sequences on both sides are opposite. An axial flux DRCRM was implemented in [13][14][15][16], and the windings on both sides were also in series and crossed. The control strategy of this axial flux DRCRM prototype under load variation was discussed in detail.…”