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WEN, JIN,CHENG, JUN-FENG The Korean Society for Computational and Applied M 2017 Journal of applied mathematics & informatics Vol.35 No.5
This paper investigates the inverse problem of determining an unknown heat radiative coefficient, which is only time-dependent. This is an ill-posed problem, that is, small errors in data may cause huge deviations in determining solution. In this paper, the existence and uniqueness of the problem is established by the second Volterra integral equation theory, and the method of trace-type functional formulation combined with finite difference scheme is studied. One typical numerical example using the proposed method is illustrated and discussed.
REGULARIZED SOLUTION TO THE FREDHOLM INTEGRAL EQUATION OF THE FIRST KIND WITH NOISY DATA
Wen, Jin,Wei, Ting The Korean Society for Computational and Applied M 2011 Journal of applied mathematics & informatics Vol.29 No.1
In this paper, we use a modified Tikhonov regularization method to solve the Fredholm integral equation of the first kind. Under the assumption that measured data are contaminated with deterministic errors, we give two error estimates. The convergence rates can be obtained under the suitable choices of regularization parameters and the number of measured points. Some numerical experiments show that the proposed method is effective and stable.
Wenjin Sun,Xiang Jin,Li Zhang,Haibing Hu,Yan Xing 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.4
This paper illustrates the analysis and design of a multi-resonant converter applied to an electric vehicle (EV) charger. Thanks to the notch resonant characteristic, the multi-resonant converter achieve soft switching and operate with a narrowed switching frequency range even with a wide output voltage range. These advantages make it suitable for battery charging applications. With two more resonant elements, the design of the chosen converter is more complex than the conventional LLC resonant converter. However, there is not a distinct design outline for the multi-resonant converters in existing articles. According to the analysis in this paper, the normalized notch frequency fr2n and the second series resonant frequency fr3n are more sensitive to the notch capacitor ratio q than the notch inductor ratio k. Then resonant capacitors should be well-designed before the other resonant elements. The peak gain of the converter depends mainly on the magnetizing inductor ratio Ln and the normalized load Q. And it requires a smaller Ln and Q to provide a sufficient voltage gain Mmax at (Vo_max, Po_max). However, the primary current increases with (LnQ)<SUP>-1</SUP>, and results in a low efficiency. Then a detailed design procedure for the multi-resonant converter has been provided. A 3.3kW prototype with an output voltage range of 50V to 500V dc and a peak efficiency of 97.3 % is built to verify the design and effectiveness of the converter.
Wenjin Sun,Hongfei Wu,Haibing Hu,Yan Xing 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.6
This paper illustrates resonant tank design considerations and the implementation of a LLC resonant converter with a wide battery voltage range based on the fundamental harmonic approximation (FHA) analysis. Unlike the conventional design at zero load, the parameter K (the ratio of the transformer magnetizing inductor Lm to the resonant inductor Lr) of the LLC converter in this paper is designed with two charging points, (Vo_min, Io_max1) and (Vo_max, Io_max2), according to the battery charging strategy. A 2.9kW prototype with an output voltage range of 36V to 72V dc is built to verify the design. It achieves a peak efficiency of 96%.
Sun, Wenjin,Jin, Xiang,Zhang, Li,Hu, Haibing,Xing, Yan The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.4
This paper illustrates the analysis and design of a multi-resonant converter applied to an electric vehicle (EV) charger. Thanks to the notch resonant characteristic, the multi-resonant converter achieve soft switching and operate with a narrowed switching frequency range even with a wide output voltage range. These advantages make it suitable for battery charging applications. With two more resonant elements, the design of the chosen converter is more complex than the conventional LLC resonant converter. However, there is not a distinct design outline for the multi-resonant converters in existing articles. According to the analysis in this paper, the normalized notch frequency $f_{r2n}$ and the second series resonant frequency $f_{r3n}$ are more sensitive to the notch capacitor ratio q than the notch inductor ratio k. Then resonant capacitors should be well-designed before the other resonant elements. The peak gain of the converter depends mainly on the magnetizing inductor ratio $L_n$ and the normalized load Q. And it requires a smaller $L_n$ and Q to provide a sufficient voltage gain $M_{max}$ at ($V_{o\_max}$, $P_{o\_max}$). However, the primary current increases with $(L_nQ)^{-1}$, and results in a low efficiency. Then a detailed design procedure for the multi-resonant converter has been provided. A 3.3kW prototype with an output voltage range of 50V to 500V dc and a peak efficiency of 97.3 % is built to verify the design and effectiveness of the converter.
Sun, Wenjin,Wu, Hongfei,Hu, Haibing,Xing, Yan The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.6
This paper illustrates resonant tank design considerations and the implementation of a LLC resonant converter with a wide battery voltage range based on the fundamental harmonic approximation (FHA) analysis. Unlike the conventional design at zero load, the parameter K (the ratio of the transformer magnetizing inductor L<sub>m</sub> to the resonant inductor L<sub>r</sub>) of the LLC converter in this paper is designed with two charging points, (V<sub>o_min</sub>, I<sub>o_max1</sub>) and (V<sub>o_max</sub>, I<sub>o_max2</sub>), according to the battery charging strategy. A 2.9kW prototype with an output voltage range of 36V to 72V dc is built to verify the design. It achieves a peak efficiency of 96%.