Maximisation of power density in permanent magnet machines with the aid of optimisation algorithms (original) (raw)
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ABSTRACT A rotordynamic analysis of two different high-speed permanent-magnet electrical machines has been performed. Their rotors are analysed separately and for each of them the analysis is performed for three different types of constructions depending on the type of the retaining sleeve. The first type of rotor construction has a carbon-fibre sleeve for retaining the magnets against the centrifugal forces and an aluminium shield for eddy currents. The retaining sleeve of the second construction is made from the titanium alloy Ti-6%Al-6%V-2%Sn and the sleeve of the third type of construction is made from the titanium alloy Ti-2.5-Cu. The last two constructions are examined without additional eddy-current shields. A numerical, finite-element, rotordynamic analysis for each type of rotor construction is performed. The numerical model is successfully compared with measured results for the natural frequencies. The analysis in this study shows that the rotor constructions retained with the titanium alloy Ti-6%Al-6%V-2%Snsleeve provide better rotordynamic properties than the other types of rotor constructions.
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A multiobjective optimization procedure for the design of interior PM motors based on Differential Evolution algorithm is presented. A comparative analysis has been carried out for the optimized 5 kW, 50 kW and 200 kW IPM motors with two and three layers of cavities in the rotor to show design tradeoffs between goals to minimize the motor volume while maximizing the power output in the field weakening regime with the back emf constraint as the main limiting factor in the design. The finite element method has been used to calculate the motor parameters during the optimization process. The effectiveness of the proposed design methodology has been shown on a 1.65 kW IPM motor with two layers of cavities in the rotor for which a prototype has been built and tested.