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In this paper, a two-leg-transfer switch structure method that can continuously supply three-phase power even when an accident occurs in a power semiconductor of a three-level active neutral-point-clamped (ANPC) inverter for railway vehicles is presented. The proposed method can minimize the ripple effect caused by power semiconductor faults by separating the faulty leg from the main circuit and connecting the load-side circuit to a neutral point. As a result of simulations, the average values of MAE and RMSE can be reduced by 1.53 [A] and 1.77 [A], respectively, when using the proposed leg-transfer switch structure compared to using the conventional structure. In the IGBT failure experiment, when the proposed method was applied to a three-level ANPC inverter, there was only a 0.21 [%] difference from the THD under normal conditions. As a result, the magnitude, phase, and total harmonic distortion of the three-phase current waveforms measured before and after the fault were identical. Thus, normal three-phase power could be effectively supplied to the load when the proposed leg-transfer switch method was applied after a power semiconductor fault occurred in the three-level ANPC inverter. If this leg-transfer switch method is applied in three-level ANPC inverterd for railway vehicles, track schedule errors can be minimized by continuously supplying three-phase power to the electric motor even when an accident occurs in a power semiconductor. [ABSTRACT FROM AUTHOR]

In this study, we propose a whole-leg scheme for the continuous control of a railway vehicle propulsion inverter. The three-leg method is commonly used to obtain the output AC power from the input DC voltage in a railway vehicle propulsion inverter. When the power semiconductor of an inverter operating in a three-leg manner fails, a problem occurs in the power supply. Therefore, this study proposes a method that automatically converts into the two-leg method without replacing the power semiconductor when it fails while the inverter is driven with the three-leg method. This leg conversion method can prevent problems in supplying power by converting the power that can be obtained from an inverter operating with the three-leg method into that obtained from an inverter operating with the two-leg method. In addition, to verify the effectiveness of the leg conversion method, a demonstrative experiment was conducted after a simulation, and an actual inverter was fabricated. Consequently, the experimental results confirmed that in an inverter operating with the three-leg method, even if the power semiconductor failed, it could be converted for operation with the two-leg method to supply power normally. [ABSTRACT FROM AUTHOR]

In this article, we deal with the onboard fast energy conversion system (FECS) that is installed in a wireless railway train (WRT), which receives electrical energy not from the wayside device but from the onboard device when traveling between stations, after getting such energy stored by fast charging during its stopping time at a station. The adopted input-series and output-independent architecture and the interleaving topology can reduce the size and weight of onboard FECS for 1500 V, which is double the operating voltage of the existing 750 V operating voltage. This allows 1200 V class insulated-gate bipolar transistor applications to increase switching frequency and reduce passive component volume. In addition, in order to secure system stability, which is important in any transportation system, a WRT must operate on the basis of simple control. Through a simple and efficient balance control based on a variable current limiter, the input voltage unbalance caused by the input voltage sharing is resolved. Also, it can control charging and discharging based on the energy moving characteristic of the train operation pattern and connection with a high-power energy storage pack. The performance of the onboard FECS at 1500 V with the proposed method is experimentally verified on a 600 kW prototype system. [ABSTRACT FROM AUTHOR]