Patent ID: 8891210
Filing Date: 2014-11-18
Classification: H02P

Abstract:
1. An electronic control unit mounted on a vehicle comprising: a capacitor that smoothes voltage of a DC power source electrically isolated from a body of the vehicle; a resistor circuit including a plurality of resistors connected in series, which is connected in parallel to the capacitor to discharge electric charge stored in the capacitor; and a fault judging circuit that judges whether or not the resistor circuit is in a fault condition by comparing the voltage across a resistor included in the resistor circuit with a fault threshold value, wherein the fault judging circuit changes the fault threshold value based on the voltage of the DC power source; wherein: the resistor circuit includes at least three resistors, the fault judging circuit includes an operational amplifier, a non-inverting input side resistor connected between a first series-connected point at a resistor included in the resistor circuit and a non-inverting input terminal of the operational amplifier, and an inverting-input side resistor connected between a second series-connected point of which potential is lower than the first series-connected point and an inverting input terminal of the operational amplifier so as to constitute a differential amplifier circuit that amplifies voltage across the resistor in the resistor circuit, and among the resistors included in the resistor circuit, a resistance value of the resistor disposed at the higher potential side of the first series-connected point and a resistance value of the resistor disposed at the lower potential side of the second series-connected point are set to be identical, and a resistance value of the non-inverting input side resistor and a resistance value of the inverting-input side resistor are set to be identical.