| 摘要 |
<p>PURPOSE:To prevent a railcar from traveling in a direction except the prescribed direction due to an erroneous operation by closing a power switch of an inverter only when the phase rotating direction of the polyphase AC output of the inverter coincides with the instruction rotating direction. CONSTITUTION:A polyphase AC signal generator 12 generates an AC signal of a phase rotating direction corresponding to a traveling direction command by a forward command signal 101 or a reverse command signal 102 irrespective of a start command signal 100. A phase rotation detector 15 detects the phase rotating direction of an AC voltage by the output signals 171-173 of the generator 12 and outputs a detection signal 18. A condition discriminator 14 outputs a start inhibit signal 19 when the signals 101, 102 and the signal 18 coincide. At this time, when the signal 100 is inputted, a main circuit closure inhibitor 13 outputs to close a power switch 3, thereby starting the inverter 11.</p> |
