Research on weakening measure of radial electromagnetic force waves in permanent magnet synchronous motors by inserting auxiliary slots

Abstract

The accurate calculation and analysis of electromagnetic force waves are especially crucial for comprehensively predicting and weakening the electromagnetic vibration of electrical machines. In this study, a fast and accurate calculation method of radial electromagnetic force density of surface‐mounted permanent magnet synchronous motor (PMSM) is presented, the radial electromagnetic force density including amplitude, frequency and order is obtained and the accuracy is verified. Comprehensively considering that the effects of the auxiliary slots on cogging torque and torque ripple, the weakening measure of radial electromagnetic force waves by inserting auxiliary slots is research, and the optimal determinations of the number and the structural parameters of auxiliary slots in PMSMs with different slot–pole combinations are summarised, and six PMSMs with 6‐pole/36‐slot (6p36s), 4p36s, 6p9s, 8p9s, 8p12s and 10p12s are analysed to verify the universality of the conclusions.

Cogging torque reduction based on segmented skewing magnetic poles with different combinations of pole‐arc coefficients in surface‐mounted permanent magnet synchronous motors

“…The E ( α ) in the wire is shown in Figure 8 when the prototype is dragged by the prime mover to run stably at 1000 r/min. The air‐gap flux density that changes with time at the centre line of the stator tooth can be obtained by the following equation [9]. …”

“…According to Maxwell's tensor method, the radial electromagnetic force density with no load of the SPMSM can be calculated by the following equation [9] …”

“…Obviously, the air‐gap permeance affected by the actual stator slot structure is difficult to be accurately calculated. Overcoming the shortcomings of the AM and the FEM in the calculation of the air‐gap magnetic field, a fast and accurate calculation method is proposed, and the electromagnetic force waves with auxiliary slots are analysed [9]. However, the accurate calculation method of air‐gap permeance in Reference [9] is only applicable to SPMSMs.…”

“…Overcoming the shortcomings of the AM and the FEM in the calculation of the air‐gap magnetic field, a fast and accurate calculation method is proposed, and the electromagnetic force waves with auxiliary slots are analysed [9]. However, the accurate calculation method of air‐gap permeance in Reference [9] is only applicable to SPMSMs. In this paper, an accurate calculation model of the air‐gap permeance (effective air‐gap length) suitable for any motor is proposed.…”

Reduction of cogging torque and electromagnetic vibration based on different combination of pole arc coefficient for interior permanent magnet synchronous machine

“…Many scholars have done a lot of research on the reduction and improvement of cogging torque and electromagnetic vibration for IPMSM [14]. Effective reduction measures such as unequal tooth width [15], harmonic pole-cutting [16], magnetic pole offset [17], pole arc coefficient selection [18], and adding auxiliary slots [19] have been proposed one after another. Stator skew slots and rotor skew poles are very popular among researchers in IPMSM for electric vehicles [20].…”