Split ratio optimisation of high‐speed permanent magnet brushless machines considering mechanical constraints

In this paper, the rotor stress is analysed for a highspeed permanent magnet (PM) machine (HSPMM) with segmented magnets retained by a carbon-fibre sleeve. The influence of rotor PM segmentation is firstly considered in the stress analysis. It is found that when the segmented magnets are under tensile stress, significant sleeve stress concentration will occur due to magnet edging effect. By contrast, the PMs will benefit from the segmentation with reduced tangential stress. This stress reduction effect is enhanced when the number of PM segments is larger. Furthermore, the influence of PM segmentation on the worst operating scenario is determined. In order to avoid stress concentration due to PM segmentation, the design guidelines are then given by investigating the influence of sleeve thickness and interference fit. A new design scheme of sleeve thickness is proposed based on the identified worst case scenarios. Finally, a 6-slot 4-pole high speed PM machine with segmented magnets retained by carbon-fibre sleeve is prototyped and tested at the speed of 90krpm. The rotor stability indirectly indicts the validity of the theoretical analysis and design scheme.

Section: Determination Of Minimum Retaining Sleeve Thickness Consisupporting

confidence: 62%

“…It was pointed out in [20] that the feasible selection of sleeve thickness is inter-dependent on the value of rotor diameter. There exists a minimum sleeve thickness for specific rotor geometry with given PM thickness and rotor outer diameter.…”

Section: Determination Of Minimum Retaining Sleeve Thickness Consimentioning

confidence: 99%

Fast calculation of carrier harmonic iron losses caused by pulse width modulation in interior permanent magnet synchronous motors

Zhu

Dong

et al. 2020

“…However, the induction generator has a complicated structure, a large amount of losses on the rotor and low efficiency [7]. Therefore, the permanent magnet (PM) generator has the advantages of simple structure and high efficiency, and is more suitable for high‐speed operation [8].…”

Section: Introductionmentioning

confidence: 99%

Multiphysics analysis of high‐speed permanent magnet generators for waste heat application

Huang

2020

In the direct drive waste heat power system, the turbine is directly connected to high-speed permanent magnet generators (HSPMGs), and the transmission efficiency, service life and system volume can be obviously improved by removing the gearbox and screw rod. However, in the design of high-speed electrical machines, a comprehensive multiphysics analysis must be conducted in order to meet various requirements of electromagnetic, mechanical and thermal specifications simultaneously. The design of one HSPMG by the multiphysics approach for the electromagnetic and loss characteristics, rotor stress, rotor dynamics and fluid-thermal parameters, which satisfies all specified multiphysics constraints, is presented. The theoretical results are confirmed by the experimental results on a prototype in terms of electromagnetic, mechanical and thermal characteristics, such as induced voltage, load current, rotor continuous operation and temperature distribution.

“…Split ratio optimisation for permanent magnet (PM) electrical machines has been a topic of importance and interests for decades [1][2][3][4][5][6], due to its vital influence on the machine performance. The split ratio optimisation has been widely applied for regular-speed machines [1][2][3][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Split ratio optimisation of high‐speed permanent magnet synchronous motor with multi‐physics constraints

Qin

Shen

2020

Split ratio is one of the most crucial parameters in a permanent magnet synchronous machine (PMSM), which has great impact on both machine torque or power, and efficiency. Extensive studies have been carried out on the split ratio optimisation. Compared with the regular‐speed machines, the high‐speed PMSM has more types of power loss playing dominant roles, and has deeper coupling of multi‐physics fields. Therefore, special concerns need be made. More comprehensive and accurate power loss estimation should be implemented; both of the critical mechanical stress constraint of the rotor and the critical thermal constraint, which in turn are associated with the machine electromagnetic performance, should be analysed and must be satisfied during optimal design. All these concerns will be presented in this study. Based on these, a procedure of the split ratio optimisation is proposed. It solely uses analytical equations which are derived in this study, hence it is simple and fast. A 250 kW, 25 krpm high‐speed PMSM is taken as a study case, and its optimisation results using the proposed procedure are validated with finite‐element analysis. Moreover, influence of the split ratio on various machine performances is discussed.