Abstract
High-speed rotating mechanical machinery is a developed, mature and reliable technology for many engineering applications. In high-speed permanent magnet machines, the rotor's permanent magnet PM is not strong enough to withstand the centrifugal force resulting from excessive rotational speed; thus, the PM material must be protected by a non-magnetic alloy sleeve. This paper presents a novel high-speed PM machine with solid rotor PM covered by a titanium retaining sleeve. The rotor stress condition is simplified as a plane stress problem according to the strength measurement of solid PM rotors in the high-speed PM motors. The analytical formulas for rotor stress are presented based on the polar coordinate displacement method. The proposed model is compared with a conventional model having auxiliary slots in stator teeth. Using a finite element analysis environment, the performance analysis shows that the proposed design has reduced magnet eddy current loss, cogging torque, and iron losses. The initial design is also optimized using a deterministic optimization algorithm that increases output torque by 26% compared to the initial design.
Highlights
The electrical machines operating at high speed have been made possible with advancements in power electronic converters
The results are computed by finite element analysis (FEA) and analytical equations for the proposed design and optimized the proposed model for high output electromagnetic torque at different working conditions
The proposed model is optimized for high output torque using deterministic optimization technique
Summary
The electrical machines operating at high speed have been made possible with advancements in power electronic converters. Various techniques are applied for estimating and minimizing eddy current losses, such as the different configurations of winding, rotor structure optimization, a shield of copper, and covering PM by conductive enclosure [13]–[15]; rotor total losses are increasing with these methods Another way to suppress the airgap permeance harmonics that caused losses is to use the PWM technique [16]; only time harmonics reduces in this case. This paper proposed a 3-slot/2-pole high-speed PM machine model using a titanium enclosure over the solid PM rotor to reduce magnet eddy current loss, cogging, and iron losses and investigate the rotor sleeve stress. The results are computed by finite element analysis (FEA) and analytical equations for the proposed design and optimized the proposed model for high output electromagnetic torque at different working conditions
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