| 摘要 |
PROBLEM TO BE SOLVED: To prevent the extension of a fault, by diagnosing the short-circuit faults of a fly-wheel diode and a plugging diode under the state before a current is made to flow through a main switching element. SOLUTION: A current is made to flow through an armature AM for a motor and a field coil FC by on-off controlling a main switching element under the state, in which a regenerative contactor C2 is turned on after a line contactor C1 is turned on, and the armature AM is rotated and a run is conducted. The values of voltage-dividing resistors R1, R2 and the value of threshold voltage Vth set to a diagnostic section 10 are set so that voltage- dividing voltage V2 is made smaller than voltage Vth when diodes FD, PD are brought to a normal state and the leakage currents of the diodes are maximized under the state, in which the contactor C1 is turned on and the contactor C2 is tuned off. Accordingly, V2<Vth holds when the diodes FD, PD are brought to the normal state regardless of diode temperatures, V2>=Vth holds when one of the diodes is short-circuited, and the fault diagnosis of the diodes can be detected, accurately by the diagnostic section 10. |
