Patent ID: 6198199
Filing Date: 2001-03-06
Classification: F02D,G01R,H02N

Abstract:
A method for diagnosing in a drive circuit having a capacitive actuator and voltage source with a positive pole and a negative pole a short circuit between the negative pole and the capacitive actuator, the drive circuit including a low-side selector switch connected in series with the capacitive actuator and a first series circuit formed of a charging capacitor and a recharging capacitor for charging the capacitive actuator, the charging capacitor disposed between the positive pole and the negative pole of the voltage source, the drive circuit further having a second series circuit formed of a charging switch, the recharging capacitor, a recharging coil, the capacitive actuator and the selector switch connected in parallel with the charging capacitor, the method which comprises:calculating a charge value corresponding to a quantity of charge QL flowing off from the recharging capacitor during a charging operation;comparing the charge value with a value .intg.idt calculated from a current i flowing during the charging operation via the selector switch connected to the capacitive actuator; anddiagnosing the short circuit of the capacitive actuator to the negative pole if .intg.idt<k*Q.sub.L where k<1.