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Jianhua Liu
School of Electrical and Power Engineering, China University of Mining and Technology, Xuzhou 221008, China

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Journal article
Published: 21 December 2017 in Energies
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Increasing the resonant frequency of a wireless power transfer (WPT) system effectively improves the power transfer efficiency between the transmit and the receive coils but significantly limits the power transfer capacity with the same coils. Therefore, this paper proposes a coil design method for a series-series (SS) compensated WPT system which can power up the same load with the same DC input voltage & current but with increased resonant frequency. For WPT systems with higher resonant frequencies, a new method of realizing soft-switching by tuning driving frequency is proposed which does not need to change any hardware in the WPT system and can effectively reduce switching losses generated in the inverter. Eighty-five kHz, 200 kHz and 500 kHz WPT systems are built up to validate the proposed methods. Experimental results show that all these three WPT systems can deliver around 3.3 kW power to the same load (15 Ω) with 200 V input voltage and 20 A input current as expected and achieve more than 85% coil-system efficiency and 79% system overall efficiency. With the soft-switching technique, inverter efficiency can be improved from 81.91% to 98.60% in the 500 kHz WPT system.

ACS Style

Xu Liu; Jianhua Liu; Jianjing Wang; Chonglin Wang; Xibo Yuan. Design Method for the Coil-System and the Soft Switching Technology for High-Frequency and High-Efficiency Wireless Power Transfer Systems. Energies 2017, 11, 7 .

AMA Style

Xu Liu, Jianhua Liu, Jianjing Wang, Chonglin Wang, Xibo Yuan. Design Method for the Coil-System and the Soft Switching Technology for High-Frequency and High-Efficiency Wireless Power Transfer Systems. Energies. 2017; 11 (1):7.

Chicago/Turabian Style

Xu Liu; Jianhua Liu; Jianjing Wang; Chonglin Wang; Xibo Yuan. 2017. "Design Method for the Coil-System and the Soft Switching Technology for High-Frequency and High-Efficiency Wireless Power Transfer Systems." Energies 11, no. 1: 7.

Journal article
Published: 17 February 2017 in Energies
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Direct current (DC) traction power systems are widely used in metro transport systems, with running rails usually being used as return conductors. When traction current flows through the running rails, a potential voltage known as “rail potential” is generated between the rails and ground. Currently, abnormal rises of rail potential exist in many railway lines during the operation of railway systems. Excessively high rail potentials pose a threat to human life and to devices connected to the rails. In this paper, the effect of regenerative power distribution on rail potential is analyzed. Maximum safety regenerative power tracking is proposed for the control of maximum absolute rail potential and energy consumption during the operation of DC traction power systems. The dwell time of multiple trains at each station and the trigger voltage of the regenerative energy absorbing device (READ) are optimized based on an improved particle swarm optimization (PSO) algorithm to manage the distribution of regenerative power. In this way, the maximum absolute rail potential and energy consumption of DC traction power systems can be reduced. The operation data of Guangzhou Metro Line 2 are used in the simulations, and the results show that the scheme can reduce the maximum absolute rail potential and energy consumption effectively and guarantee the safety in energy saving of DC traction power systems.

ACS Style

Guifu Du; Dongliang Zhang; Guoxin Li; Yihua Hu; Yang Liu; Chonglin Wang; Jianhua Liu. Maximum Safety Regenerative Power Tracking for DC Traction Power Systems. Energies 2017, 10, 244 .

AMA Style

Guifu Du, Dongliang Zhang, Guoxin Li, Yihua Hu, Yang Liu, Chonglin Wang, Jianhua Liu. Maximum Safety Regenerative Power Tracking for DC Traction Power Systems. Energies. 2017; 10 (2):244.

Chicago/Turabian Style

Guifu Du; Dongliang Zhang; Guoxin Li; Yihua Hu; Yang Liu; Chonglin Wang; Jianhua Liu. 2017. "Maximum Safety Regenerative Power Tracking for DC Traction Power Systems." Energies 10, no. 2: 244.

Journal article
Published: 09 September 2016 in Energies
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Running rails used as a return conductor and ungrounded scheme have been widely adopted in DC traction power systems. Due to the longitudinal resistance of running rails and insulation resistance of rail-to-ground, there will be a potential rise between running rails and the ground when return current flows through the running rails, which is known as rail potential. At present, abnormal rise of rail potential exists widely in DC traction power systems. The present rail potential model still cannot simulate and explain the abnormal rail potential in the system. Based on the analysis of power distribution with multiple trains running in multiple sections, a dynamic simulation model of rail potential in the whole line is proposed. The dynamic distribution of rail potential and stray current in DC traction power systems when multiple trains run in multiple sections is analyzed, and the impact of traction current distribution on rail potential is evaluated. Simulation results show that the abnormal rise of rail potential during the dynamic operation of the system can be evaluated effectively.

ACS Style

Guifu Du; Dongliang Zhang; Guoxin Li; Chonglin Wang; Jianhua Liu. Evaluation of Rail Potential Based on Power Distribution in DC Traction Power Systems. Energies 2016, 9, 729 .

AMA Style

Guifu Du, Dongliang Zhang, Guoxin Li, Chonglin Wang, Jianhua Liu. Evaluation of Rail Potential Based on Power Distribution in DC Traction Power Systems. Energies. 2016; 9 (9):729.

Chicago/Turabian Style

Guifu Du; Dongliang Zhang; Guoxin Li; Chonglin Wang; Jianhua Liu. 2016. "Evaluation of Rail Potential Based on Power Distribution in DC Traction Power Systems." Energies 9, no. 9: 729.