| 摘要 |
PROBLEM TO BE SOLVED: To detect discontinuity of a snubber resistor constituting a snubber circuit for a switching element, which chopper controls a DC motor. SOLUTION: A traveling motor 1 is provided with an armature 1a and a field winding 1b, to which a forward contactor 3 and a reverse contactor 4 are connected. A diode 8 and a capacitor 9 making up a snubber circuit are connected in series between the collector and emitter terminals of a switching transistor 7 connected in series to the traveling motor 1 and a snubber resistor 10 between the capacitor and a battery 2. A controller 12 connected to the battery 2 is provided with a microcomputer 13 and a drive circuit 14. The microcomputer 13 is connected to a point P between the capacitor 9 and the snubber resistor 10 via an AD converter 15. If the output of the AD converter 15 is equal to or more than a driving-time reference voltage at the time of chopper control, the microcomputer 13 judges the snubber resistor 10 to have been discontinued. |
