Analysis of cogging torque caused by manufacturing tolerances of surface‐mounted permanent magnet synchronous motor for electric power steering

Kim, Ji Min; Yoon, Myung Hwan; Hong, Jung-Pyo; Kim, Sung Il

doi:10.1049/iet-epa.2015.0641

Cited by 32 publications

(36 citation statements)

References 19 publications

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“…From Equations (8) and 9, some variables such as A m , K l , K r , K φ and K c can be deployed into more detail design variables if necessary. In this paper, the three highly significant design variables, i.e., the airgap length, MT, MPA on the OCAF and its variation are investigated in detail.…”

Section: Tolerance Sensitivity Analysis Using Partial Derivative Methodsmentioning

confidence: 99%

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Tolerance Sensitivity Analysis and Robust Optimal Design Method of a Surface-Mounted Permanent Magnet Motor by Using a Hybrid Response Surface Method Considering Manufacturing Tolerances

Jun

Kwon

2018

Energies

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This paper presents a robust optimal design method using a hybrid response surface method (H-RSM) which directly finds an optimal point satisfying a target Z-value or a probability of failure. Through three steps, this paper achieves the goal that is to increase the open-circuit airgap flux (OCAF) in a surface-mounted permanent magnet motor and decrease its variation caused by variations of the airgap lengths including an additional one between permanent magnets and rotor back yoke. First, the OCAF equation is derived from the magnetic equivalent circuit (MEC) considering the additional airgap. Then, the equation is validated by comparing its results with those of the finite element method (FEM) modeled by the slotless stator. Next, the tolerance sensitivity analysis, using the partial derivative of the OCAF equation with respect to the airgap length, is performed to investigate the effects of design variables on the OCAF. It is shown that increasing the magnet thickness is effective for both increasing mean of the OCAF and reducing its variation. Finally, robust optimal design is performed using the H-RSM, in which all data are obtained from the FEM modeled by the slotted stator. The results of the robust optimal design are verified using the FEM.

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Section: Tolerance Sensitivity Analysis Using Partial Derivative Methodsmentioning

confidence: 99%

“…The influence of additional airgaps, which is caused by the manufacturing tolerances between segmented stator cores which is used for the higher fill factor, on the cogging torque was analyzed by using the FEM or analytical solutions in [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Tolerance Sensitivity Analysis and Robust Optimal Design Method of a Surface-Mounted Permanent Magnet Motor by Using a Hybrid Response Surface Method Considering Manufacturing Tolerances

Jun

Kwon

2018

Energies

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“…However, since there are many possible manufacturing errors such as eccentricity, machining error, and unevenly magnetized magnets, motors always contain non-ideal components. As a result of those errors, the measured cogging torque of the actual motor may be very different from what is expected in the simulation [12]. This phenomenon can be a critical issue to those applications that need precision control of the motor and are sensitive to noise and vibration.…”

Section: Introductionmentioning

confidence: 89%

Mitigation Method of Slot Harmonic Cogging Torque Considering Unevenly Magnetized Permanent Magnets in PMSM

2019

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This paper presents a mitigation method of slot harmonic cogging torque considering unevenly magnetized magnets in a permanent magnet synchronous motor. In previous studies, it has been confirmed that non-uniformly magnetized permanent magnets cause an unexpected increase of cogging torque because of additional slot harmonic components. However, these studies did not offer a countermeasure against it. First, in this study, the relationship between the residual magnetic flux density of the permanent magnet and the cogging torque is derived from the basic form of the Maxwell stress tensor equation. Second, the principle of the slot harmonic cogging torque generation is explained qualitatively, and the mitigation method of the slot harmonic component is proposed. Finally, the proposed method is verified with the finite element analysis and experimental results.

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“…Jung et al improved cogging torque by making the rotor shape cosine with pore flux density [8]. Kim et al and Coenen et al analyzed the period and amplitude of the additional cogging torque that occurs when a tolerance occurs in the motor [9,10].…”

Section: Introductionmentioning

confidence: 99%

Tolerance-Insensitive Design of the Magnet Shape for a Surface Permanent Magnet Synchronous Motor

et al. 2020

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Many studies have been conducted to reduce the cogging torque of electric power steering motors. However, in the mass production of such motors, it is essential to enhance performance robustness in relation to tolerances. For such motors, this work analyzes performance robustness in relation to tolerances by applying a cycloid curve to the surface magnet of the rotor. Applying a cycloid curve to the magnet surface of the rotor is one of several ways to reduce cogging torque. To evaluate the performance of the cycloid curve, we compare it with an eccentric curve. The two curves are compared for the same specifications and evaluated using the indicator, tolerance insensitivity rate, which is used to assess performance robustness in relation to tolerances. The cycloid curve was evaluated to be more robust in relation to tolerances, as compared with the eccentric curve. Finally, an experiment was conducted to validate the robustness of the cycloid curve.

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Analysis of cogging torque caused by manufacturing tolerances of surface‐mounted permanent magnet synchronous motor for electric power steering

Cited by 32 publications

References 19 publications

Tolerance Sensitivity Analysis and Robust Optimal Design Method of a Surface-Mounted Permanent Magnet Motor by Using a Hybrid Response Surface Method Considering Manufacturing Tolerances

Tolerance Sensitivity Analysis and Robust Optimal Design Method of a Surface-Mounted Permanent Magnet Motor by Using a Hybrid Response Surface Method Considering Manufacturing Tolerances

Mitigation Method of Slot Harmonic Cogging Torque Considering Unevenly Magnetized Permanent Magnets in PMSM

Tolerance-Insensitive Design of the Magnet Shape for a Surface Permanent Magnet Synchronous Motor

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