Denso Corporation

Shunya Yamamoto

Ryotaro Miura

Yukihiro Tomonaga

Kazutaka Honda

A battery pack monitoring system comprises first and second wirings connected to each battery cell, an RC filter formed of a resistor and a capacitor, and a discharging switch provided between two second wirings in a voltage monitoring device. The first and second wirings and the discharging switch are also connected to both ends of an inter-group group wire. In the second wiring of each battery cell, a discharging resistor is provided not to cause discharging of the charge in the capacitor. In the second wiring connected to a low voltage side for the inter-group wiring, a current limiting resistor having a higher resistance value than the discharging resistor is provided. A substitute discharging switch and a discharging resistor are provided so that the substitute discharging switch is turned on upon a voltage drop generated when current flows through the current limiting resistor.

Battery pack monitoring system

A voltage detecting device detects a differential voltage between two input nodes having a non-zero common mode voltage. A differential voltage detecting circuitdetects the differential voltage by sampling each voltage of the input nodes and outputs a detection voltage indicating a detection result. A leak canceling circuit generates a compensating current, which flows in opposition to a leak current flowing out from the input nodes in correspondence to an operation of the differential voltage detecting circuit. An operation control part controls the leak canceling circuit to perform or stop a canceling operation. A failure diagnosing part performs a failure diagnosis about the leak canceling circuit based on a first detection value and a second detection value of the detection voltages, which are detected during periods when the leak canceling circuit performs and stops the canceling operation.

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Kariya, Japan

Shunya Yamamoto