A Study on Interference between Primary and Secondary Controls in Railway Wireless Power Transfer Systems with Multiple Secondary Coils

Abstract

Primary and secondary circuits in railway wireless power transfer (WPT) systems have control systems to maintain constant primary current and constant secondary output power. Their control systems lack quick response capability because the primary and secondary circuits utilize LC circuits to smooth the DC output voltage of rectifiers. Therefore, the stability of railway WPT systems utilizing multiple secondary coils should be studied. However, it is difficult to analyze transfer function in non-linear WPT systems and to conduct frequent experiments utilizing actual railway vehicles. Therefore, a linearized model of a non-linear WPT system utilizing an imaginary dq transformation is proposed. In addition, this paper examines the relationship between the stability of the WPT system and the number of operating secondary coils by calculating the pole assignment. Moreover, an experimental model of a railway WPT system that is required to supply several hundred kW of power for railway vehicles is proposed to experimentally examine the stability of railway WPT systems.