Abstract
The low speed toothed doubly salient permanent-magnet (TDSPM) machine is an interesting candidate motor for electric ship applications because, of its high torque output, maintenance-free operation and flexible working modes, which gives the opportunity to increase system’s reliability, and decrease the system size, weight and noise which are key features for naval applications. However, particularly in the 3-phase configuration, the stator and rotor saliency of these machines leads to a high level of torque ripple. To overcome these drawbacks, the use of polyphase machines (with a number of phases greater than three) can be a relevant solution. In this paper, an optimal design of two kind of novel 4-phase motors is performed in order to fulfil the specifications of a high power naval ship propulsion. The designs aim to maximize the torque to mass ratio. The motors’ performances are directly linked to their structural parameters, so, the impact of the coil number in terms of mean torque, torque ripple, energy ratio values, and efficiency is also presented and analysed. The design of these two electromagnetic structures, as well as the determination of their electromagnetic performances, are carried out using a particle swarm optimization algorithm (PSO) with taking into account thermal constraint. The performance of the proposed machine in terms of mean torque, torque ripple, energy ratio, and efficiency values is presented and analysed. The results obtained reveal that the TDSPM machines with four poles/phase are good candidates to meet the requirements of high power direct-drive ship propulsion system.
Highlights
Numerous research studies have been conducted on various electrical motors topologies associated with power electronics drives as well as conventional wound field synchronous machines (WFSMs), permanent magnet synchronous machines (PMSMs), induction machines (IMs) and unconventional permanent magnet structures [2,3,4,5,6,7,8,9,10,11,12,13,14]
particle swarm optimization algorithm (PSO) optimization process coupled with finite element method (FEM) is applied to determine the optimal design of the 4-phase toothed doubly salient permanent-magnet (TDSPM) machines to maximize the mass-to-torque ratio
PM machines with two and four coils/phase have been investigated using an optimal design process based on particle swarm optimization
Summary
In ships (research vessels and special purpose ships), increasing compactness is challenging. This point differs significatively from other machine topologies which can be proposed for marine propulsion motor application such as stator PM Flux switching motors or classical PM motors where PMs are located in the stator teeth or housed in the rotor respectively [16,17,18] This feature allows a priori to increase the simplicity and the robustness of the machine design and to use only a very limited number of magnets. It includes large-toothed poles which carry a large number of small rotor teeth leading to the decrease, for a given electrical frequency, of the rotor speed. Both two and four coils per phase structures are studied and compared
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