Applied sciences

Bulletin of the Polish Academy of Sciences: Technical Sciences

Content

Bulletin of the Polish Academy of Sciences: Technical Sciences | 2020 | 68 | No. 3 |

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Abstract

In this study, the optimization of air gap magnetic flux density of open slotted axial flux permanent magnet (AFPM) machine which was developed for wind turbine has been obtained using the Taguchi experimental method. For this, magnetic analyzes were performed by ANSYS Maxwell program according to Taguchi table. Then the optimum values have been determined and the average magnetic flux density values have been calculated for air gap and iron core under load and no-load conditions with ANSYS Maxwell. Traditionally, 15625 analyzes are required for 6 independent variables and 5 levels when experimental method is used. In this study, optimum values are determined by 25 magnetic analyzes, which use L25 orthogonal array. For this purpose, both factor effect graph and signal to noise ratios are used, according to the factors and levels which are obtained from the factor effect graph and the signal to noise ratio. Parameters are re-analyzed by Maxwell. The optimum factors and levels are determined. For optimized values, the air gap magnetic flux density is improved by 65.7% and 173.26%, respectively, according to the average value and the initial design. Therefore, the variables are optimized in a shorter time with Taguchi experimental design method instead of the traditional design method for open slotted AFPM generator. In addition, the results were analyzed statistically using ANOVA and Regression model. The variables were found to be significant by ANOVA. The degree of influence of the variables on the air gap magnetic flux density was also determined by the Regression model.

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Authors and Affiliations

E. Hüner
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Abstract

Based on the rolling bearing vibration measurement principle in ISO standard, a nonlinear dynamic model of ball bearing is built and motion equations of the inner ring, outer ring, and rolling elements are derived by using Lagrange’s equation. The ball bearing model includes the influence of waviness, rotational speed, external load, arbor supporting stiffness and arbor eccentricity. Ball bearing high-speed vibration tests are performed and used to verify the theoretical results. Simulated results showed that specific waviness orders produced the principal frequencies that were proportional to rotational speed. Rotational speed mainly affected the value of the natural frequency of the bearing system, and RMS (Root Mean Square) of the full band had a great fluctuation with the increase of rotational speed. In the experiment, spectrum and RMS of 2fs-30 kHz (fs: the rotational frequency of inner ring/arbor) under high speed could include not only the influence of rotational speed but also principal frequencies produced by waviness, which could cover the part of requirements of the standard bearing vibration measurement.

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Authors and Affiliations

P.P Hou
L.Q. Wang
Q.Y. Peng

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