| 摘要 |
PURPOSE:To carry out smooth reversing by setting a second set value lower than a first set value in a DC intermediate circuit for stopping the main circuit and not stopping the main circuit, when the voltage or the DC intermediate circuit reaches the second set value, but short-circuiting the positive and negative electrodes of the DC intermediate circuit through a resistor. CONSTITUTION:A suppression voltage setter 31 sets a second set value lower than a first set value being set by an overvoltage setter 21 and when a suppression voltage detector 32 detects that the voltage of the DC intermediate circuit has reached the second set value, an operation start command is delivered through an OR element 33 to a suppression switch 17. Since the suppression voltage detector 32 delivers the operation command only to the suppression switch 17 and does not deliver the operation command to a protection signal generating circuit 23, only voltage suppressing operation is effected by means of the suppression switch 17 and a voltage suppressing resistor 18 even if the voltage of the DC intermediate circuit begins to increase during reverse starting operation and thereby the main circuit is not stopped. According to the constitution, an AC electric vehicle can be started in the climbing direction on an inclining railway. |
