Improved V‐shaped interior permanent magnet rotor topology with inward‐extended bridges for reduced torque ripple

Abstract

Interior permanent magnet synchronous machines (IPMSMs) with V‐shaped permanent magnet (PM) rotors are widely used as traction motors in electric vehicles because of their high torque density and high efficiency. However, the V‐shape IPMSMs have the disadvantages of inevitable torque ripple due to the non‐sinusoidal air‐gap flux density distribution and the utilisation of the reluctance torque. In this study, with the aim of improving the torque ripple characteristics, a modified V‐shaped IPMSM rotor configuration with bridges extended inwards towards the pole centre is proposed to generate a more sinusoidal air‐gap flux density waveform. The proposed topology, referred to as ‘Type C’ within this study, is compared with baseline rotor configuration references, namely ‘Type A’ which is a conventional V‐shaped PM rotor, as well as ‘Type B’ which is a related configuration with a mechanically non‐uniform air gap. The analysis results show that the rotor ‘Type C’ exhibits significant advantages in terms of reducing cogging torque, torque ripple and radial force, without incurring additional air‐gap friction losses. Finally, a prototype of the IPMSM with the proposed rotor configuration is manufactured and tested, verifying the predicted benefits experimentally.

Analysis of Multi-Objective Optimization Design of Interior Double Radial and Tangential Combined Magnetic Pole Permanent Magnet Drive Motor for Electric Vehicles

“…In addition to the improvement of the motor structure, the design parameters of the motor can also be determined by an optimization algorithm, so as to improve the motor's electromagnetic performance. The traditional optimization methods mostly use a single objective for optimization, which not only requires tedious calculation steps and a long development time but also the mutual influence between design parameters is generally ignored, making it difficult to obtain the optimal parameters [15][16][17]. Study [18] takes high torque density as a single optimization objective for the flux-switched permanent magnet motor, selects parameters such as pole arc coefficient and magnetization thickness of permanent magnets for analysis, and uses finite element analysis to repeatedly adjust structural parameters based on single parameter scanning method to design the motor.…”

Optimal Design of High-Speed Electric Machines for Electric Vehicles: A Case Study of 100 kW V-Shaped Interior PMSM

“…Reference [7] proposes topology modification of a flat inserted permanent magnet synchronous machine (PMSM) based on magnet segmentation to ensure a maximum rotational speed of 35,000 rpm. Geometric modifications of the rotor are also proposed in [8,9] to improve performances of the V-shaped interior PMSM (IPMSM) for vehicle application. Different machine's topologies have been compared to select the suitable one for electric vehicle application [10] and high-speed application [11].…”

Investigation of the impact of rotor shaping on the torque and radial force harmonics of a V‐shape interior permanent magnet synchronous machine

“…Design-based torque ripple reduction centres on optimising machine parameters and geometry during the design phase [13], while control-based reduction involves optimising current injection and shaping the current profile [14,15]. In the designbased optimisation of IPMSMs, various aspects and parameters can be targeted, including PM shaping [16,17], PM placement and distribution [18,19], skewing of the rotor or stator -185 [20][21][22], rotor bridge shaping [23], rotor surface shaping [24][25][26][27], and pole geometry modifications [28,29].…”