Control method for increasing motor power of DC-electrified railway vehicles with an onboard energy storage system

In this paper, a novel DC bus voltage control strategy of the traction system is proposed for overhead line and energy storage device (ESD) hybrid railway vehicles. This strategy realizes the increase of regenerative brake energy and reduction of consumed energy in the powering by boosting the traction motor voltage. When a DC bus voltage boost is applied, the traction system is separated from the overhead line by a breaker, which is generally equipped. This paper proposes a strategy considering both breaker operation and energy management of onboard ESD. The static state is calculated to reveal the effect of the reduction of energy consumption and the energy management of ESD by applying the proposed control method. The calculation results confirmed a 10.1% and 8.87% decrease in total energy consumption when the DC bus voltage was boosted to 1950 V for single and multiple travel between several stations, respectively. Moreover, the proposed energy management method was verified at 4 patterns of the DC bus voltage. A numerical simulation was also performed to verify the dynamic characteristic, especially from an overvoltage point of view. As a result, the DC bus voltage can be regulated without detecting overvoltage.