Search

In order to solve the problem of difficult simulation of the bolted joint structure of rotors, this study proposes an improved sub-regional thin-layer element method (ISRTL) and applies it to the equivalent simulation of the joint interface in the presence of bolt deviations. The theory introduces the fractal theory and Hertz contact theory to calculate the thin-layer parameter for the region with weak influence of bolt preload. The trend of dynamic response under different loosening deviation conditions is investigated. The experimental study of bolt deviation under axial tension and transverse vibration was carried out using a drum-disk rotor. The frequency and stiffness with bolt loosening position conform to M-type trend. The error of the eigenfrequencies calculated by the proposed method is within 3 % from the experimental results. The results demonstrate that ISRTL method has high accuracy and efficiency in the simulation study for the assembly deviation of rotor bolt connections. [ABSTRACT FROM AUTHOR]

This article proposes a novel asymmetric interior permanent magnet (AIPM) rotor topology that has a mixed V-shape and spoke-type PM configuration, designated as a 1.5-layer PM structure, and asymmetric arrangement of V-shape PMs and asymmetric flux barriers. The AIPM rotor topology is employed for IPM synchronous machines to utilize the magnetic-field-shifting (MFS) effect for increasing average torque by reducing the current angle difference between peak PM and reluctance torque components. Three machines, i.e., the proposed 1.5-layer AIPM, a symmetrical 1.5-layer IPM-I, and a conventional V-shape benchmark IPM-II are designed and optimized using the same stator, rotor diameter, and total PM usage by global parametric optimization considering the mechanical stress. The effect of asymmetric features of the 1.5-layer AIPM rotor design, i.e., asymmetry of V-shape cavity as well as position and dimensions of flux barrier, on maximum torque and open-circuit air-gap field are investigated. The electromagnetic performances of three machines are compared. It confirms that the proposed AIPM machine has the highest maximum torque and the smallest cogging torque simultaneously. It is also revealed that the torque enhancement is achieved by both the 1.5-layer structure and MFS effect. Finally, a prototype of an AIPM machine is manufactured and tested to validate the analyses. [ABSTRACT FROM AUTHOR]

This article proposes a novel asymmetric interior permanent magnet (AIPM) rotor topology for torque enhancement and torque ripple reduction in IPM synchronous machines. The AIPM rotor structure is featured by a hybrid-layer permanent magnet configuration, i.e., for each pole, a part of PM configuration has one-layer while the other part has two layers. It allows the magnetic-field-shifting (MFS) effect to be utilized by reducing the current angle difference between maximum PM and reluctance torque components, thereby effectively increasing the maximum resultant torque. The proposed AIPM machine and a conventional V-shape IPM machine are designed and globally parametric optimized with the same 24-slot/4-pole stator, rotor diameter, and PM usage. The influence of key rotor geometric parameters of the AIPM machine on torque and open-circuit air-gap magnetic field characteristics are investigated. The comparison of electromagnetic performance confirms that significant torque enhancement and torque ripple reduction in the AIPM machine compared with the conventional V-shape IPM machine and reveals the MFS effect is essential for torque increase. Finally, an AIPM machine is manufactured and tested for validation. [ABSTRACT FROM AUTHOR]

This paper proposes a spoke-type interior permanent magnet (IPM) machine with novel alternate airspace barriers, through which higher torque capability and better manufacturability can be obtained, without remarkable deterioration in mechanical strength. Further, the influence of end leakage flux in the novel IPM design is investigated by three-dimensional finite element method, including the leakage flux characteristics and torque capability. Furthermore, a step-staggered rotor is proposed to reduce the unipolar leakage flux and magnetization of the end shaft. As an extension, unipolar leakage flux is further investigated in consequent-pole PM machines, as well as the validity of step-staggered method. Finally, prototypes are fabricated and tested to verify the foregoing analyses, including the magnetic field at the end shaft and the output capability. [ABSTRACT FROM AUTHOR]

This paper overviews high-speed permanent magnet (HSPM) machines, accounting for stator structures, winding configurations, rotor constructions, and parasitic effects. Firstly, single-phase and three-phase PM machines are introduced for high-speed applications. Secondly, for three-phase HSPM machines, applications, advantages, and disadvantages of slotted/slotless stator structures, non-overlapping/overlapping winding configurations, different rotor constructions, i.e., interior PM (IPM), surface-mounted PM (SPM), and solid PM, are summarised in detail. Thirdly, parasitic effects due to high-speed operation are presented, including various loss components, rotor dynamic and vibration, and thermal aspects. Overall, three-phase PM machines have no self-starting issues, and exhibit high power density, high efficiency, high critical speed, together with low vibration and noise, which make them a preferred choice for high-performance, high-speed applications. [ABSTRACT FROM AUTHOR]