Study of a new hybrid switch for the application in the railway

The DC switch is widely used in the railway locomotive system. Electrical arc erosion generated when the switch is operated is the primary factor that affects the life-span of high-power switch, which is harmful to the reliability of the whole system. In this paper, a whole new design method is proposed for the DC 110V/250A hybrid switch which is composed of the power electronic switch, the storage capacitors and the mechanical contactor in parallel. The electrical switch MOSFET is conducted through capturing the signal of the contact voltage when the mechanical switch is making to eliminate the bouncing electrical arc of the contactor. And the capacitors are used to absorb the energy of arc generated when the contractor is breaking. This paper presents a method to extract the parasite parameters and makes optimum design for the hybrid switch. The experiment results show that the influence of arc is mostly eliminated when the hybrid switch is operated so that the reliability and electrical life-span of the switch are enhanced. The new design method of the hybrid switch is quite different from the traditional design idea and makes it possible for the hybrid switch to be utilized in high power situation more extensively, which shows a good market prospect. The new hybrid switch has been used in the railway system and has a good effect.