| 摘要 |
PROBLEM TO BE SOLVED: To diagnose the capacity of a back-up capacitor with high accuracy even if a discharging diode and a charging diode are omitted. SOLUTION: This system is composed to be provided with an ignition circuit 3, a back-up capacitor 6 and a control circuit containing a computer 11. In this case, the output voltage of a pressure rise circuit 5 is pressure rised from a first voltage to a second voltage on the basis of the control of the control circuit, the pressure rise set value then returned to the second voltage after a back-up capacitor 6 terminal voltage reaching the second voltage, and capacitive suitablility of the back-up capacitor 6 is diagnosed on the basis of the descending voltageΔV1 of the back-up capacitor 6 terminal voltage after elapse of T time and a terminal voltageΔV2 of the terminal voltage when a constant current I is electrified from the back-up capacitor 6 to the load thereafter for T time.
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