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Transformerless Bidirectional DC-DC Converter for Battery Storage System with High Voltage Gain
Hailong Zhang,Yafei Chen,Chang-Su Shin,Sung-Jun Park,Dong-Hee Kim 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
Bidirectional DC-DC converters with wide voltage conversion ratio are essential in energy storage systems. In these systems (ESS), cost effective design is important factor, therefore, it needs to be designed with small numbers of component. This paper proposes a family of high voltage gain bidirectional converter based on the integration of Boost converter with Ćuk, SEPIC, BUCK-BOOST converters respectively. Detail comparisons are progressed in terms of operating mode, numbers of component, and efficiency. The experiment results are carried to verify the proposed converter family. The results show that converter I present the highest efficiency in boost mode (92%) and in buck mode (92.2%).
Jun Zou,Jaebok Lee,Yafei Ji,Sughun Chang Institute of Electrical and Electronics Engineers 2007 IEEE transactions on power delivery Vol.22 No.4
<P>This paper describes an efficient numerical approach for the calculation of the per-unit length earth-return impedance of a conductor inside a tunnel. The influence of the tunnel on the per-unit length impedance is replaced by a set of equivalent current sources via the fictitious medium method. The main advantage of the proposed approach is that it can solve the boundary value problem within the tunnel region. The proposed method can reduce the calculation region and, thus, leads to time savings. A comparison of the numerical results with published data shows very good agreement. The proposed method is a good candidate for impedance calculation of a conductor inside a tunnel.</P>
Fixed‑time non‑singular terminal sliding mode control for PMSM drive systems
Huixiang Liu,Keqi Mei,Lu Liu,Yafei Chang,Shihong Ding,Hanzhang Zhang,Jun Wang 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.2
To further improve the response speed and anti-interference capability of permanent magnet synchronous motors (PMSMs), many advanced control algorithms have been developed. Among the various advanced controls, the fixed-time terminal sliding mode control is one of the effective methods. However, there are still some problems, e.g., too many parameters imposed on the control design in the existing results. In this paper, a fixed-time non-singular terminal sliding mode control (FTNTSMC) method is proposed for the speed loop of a PMSM drive system. First, to improve the closed-loop performance of the PMSM drive system, the relationship between the reference q-axis current and the speed of the PMSM is described in a second-order model. Next, a sliding mode surface with variable exponential coefficients is selected, and the expression of the controller is given. Then, the stability of the PMSM drive system is demonstrated by using Lyapunov functions. Using this method, the fixed-time convergence of the PMSM drive system can be realized and the occurrence of singularity phenomena can be avoided in a simpler and easier method. Finally, the effectiveness of the proposed method is verified by simulation and experimental results.