| 摘要 |
<p>PURPOSE:To prevent a brake series resistor from overheating or burning out by forcibly opening a main circuit when the fact that a malfunction occurs in the output of the final stage of a frequency divider is detected. CONSTITUTION:A frequency signal 16 outputted from a frequency divider 15 is used to decide the widths of the ON and OFF pulses of a chopper 12. A frequency signal 17 corresponds to a repetition control frequency for the chopper 12, and a frequency signal 18 is used to control a shortcircuit switch 11 of a brake series resistor 10. If the oscillation of the divider 15 is stopped, the oscillation of the signal 18 of the output from the final stage is stopped. Accordingly, a coil of a control relay 28 is demagnetized. Thus, a solenoid valve 30 is demagnetized to turn the corresponding switch 3 OFF, and a main circuit of a chopper controller is opened.</p> |
