At substations of Shinkansen, three-phase power received from the utility power system is converted into a pair of single phase power sources with different phases. When a Shinkansen car passes the boundary of two power sources with different phases, the power source for Shinkansen instantly switches from one to the other. Vacuum switches have been used as changeover switches so far. It takes about 300 msec for switching. By this system, Shinkansen cars can pass the boundary of two power sources under powering.
Generally speaking, when a vacuum switch is closed at a voltage-phase of 90°, the inrush current into transformer will become small. On the other hand, although the power from substation is not supplied to Shinkansen at no-voltage of power source switching at the changeover section, counter electromotive force by auxiliary motor appears on the main transformer on the car. Due to the counter electromotive force, it is difficult to suppress the inrush current into the main transformer by the conventional vacuum switch. In contrast, the use of static switch such as semiconductor device can decrease the exciting inrush current into the transformer of Shinkansen car, when the turn-on timing of changeover switch is controlled. We investigated the control method for suppressing the exciting inrush current into transformer when a static switch is used as a changeover switch instead of vacuum switch. To verify the control method, we built and tested a mini model to simulate a changeover switch.
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