The increasing performance of modern electric locomotives results in slip-stick vibrations in the traction drive-train due to wheel-rail contact. This can be remedied by the introduction of a novel modal state control scheme for active oscillation damping to avoid the loss of traction force caused by passive slip readhesion control. This paper describes the basic concept of the active control scheme enhanced with anti-windup and a simple starting method that can use any standard controller. The limits of the active control scheme are pointed out and are circumvented by coupling with passive readhesion control. The resulting control scheme benefits from the advantages of both control concepts utilized with different adhesion force gradients. Finally, the predicted performance of the novel control is compared with the installed control concepts based on several test runs with a European high-performance locomotive.
In this paper, we propose a minimization design method of the inductance and the capacitance of the flying capacitors for a multi-level flying capacitor DC-DC boost converter (FCBC). The effectiveness of the small capacitances of the flying capacitors in three-level and five-level FCBCs is investigated. We experimentally confirmed that the distortion of the voltage across the input source and the input inductor is drastically reduced by increasing the number of levels. Thus, a small inductance value and a small capacitance value can be used for the input inductor and the flying capacitors, respectively, in an n-level FCBC. Therefore, the minimization of passive components in multi-level FCBCs is achieved. Moreover, the achieved maximum efficiencies of the designed three-level and five-level FCBCs are 98.5% and 97.8%, respectively, at an output power of 1kW.
The powertrain of electric vehicles in the market has a problem in that its performance degrades because of fluctuations in battery voltage. In order to solve this problem, this paper proposes an energy conversion system to boost a part of the electric vehicle battery voltage. This system consists of the existing electric vehicle powertrain and a bi-directional isolated DC-DC converter called the dual active bridge (DAB). This system is able to compensate for battery voltage drops with high efficiency by using a small capacity DAB converter. In addition, a control method for the DAB converter is proposed. This control method achieves a better response to the transient state than conventional methods. The validity of the proposed system and its control method are confirmed by simulation and experiments. A high efficiency of about 99% is obtained from the experimental system prototype.
In this paper, concerned with an energy storage system (ESS) with Li-ion battery for DC traction power system, a study about planning of introducing ESS and the performances of two examples in actual operation are described. Through this study, a suitable condition for introducing ESS with respect to headway of trains was obtained and confirmed by analysis measurements. Further, the effects of adjusting threshold voltages of charge and discharge on the practical use of ESS are also described.
In this study, a PID controller with the proposed control strategy is presented, which is used to improve the dynamic response. During the load transient period, the parameters of the proposed controller are on-line adjusted and make the controller design easy. As compared with the traditional PID control, the proposed control strategy does not need additional hardware circuits. In addition, the corresponding calculation flow chart is varied as minimum as possible, such that the parameters of the PID controller is of easiness and generality.