Studying On New Method For Auto-Passing Phase Separation Of AC Locomotive

The problems in the operation of Phase Separation in the mode of Insulated Overlaps (PSIO) such as electric arc, over-voltage and inrush current of transformer has severe influence on the railway safety operations and has been paid high attention by scientific researchers and engineers. In order to realize no electric arc, over-voltage and inrush current in passing though Phase separation, a new method which is based on the main circuit of AC locomotive for auto-passing PSIO is put forward in the paper.The paper makes a detailed analysis of the disadvantages when electric locomotive passing though Phase separation. There are mainly two reasons which causes the electrical hazard in PSIO. The first reason is the operation of electric locomotive which causes over-voltage and inrush current; the second reason is the structure of insulated overlap which caused electric arc.The strategy which is based on the control of the main transformer primary current and voltage when open or close the main breaker is put forward. Because of the limit of the frequency of Insulated Gate Bipolar Transistor on locomotive, the theory of single pole double frequency SPWM, linear triangular carrier control and carrier phase-shifting SPWM are all introduced in the paper whose aim is to increase the equivalent frequency of the circuit.What's more, the mechanism of arc in air and the process of the arc in PSIO are detailed analyzed, the method by change the structure of electric field to suppression the arc is put forward.The control solution makes asynchronous motor run in the state of electric regenerative braking during PSIO to control the feedback energy and keep the DC circuit voltage constant. if the auxiliary system of electric locomotive gets the energy from DC circuit, the control strategy can realize uninterrupted power supply for auxiliary system.The each process of new method for auto-passing PSIO is detailed analyzed in the paper. By the whole system modeling and simulation, the paper gets the characteristic of transient state. Aiming at the new plans for auto-pass PSIO, the paper also makes the proper control method for each process.