Patent ID: 11867768
Assignee: DENSO TEN LIMITED
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 15:
16. A failure detection method executed by a battery voltage measurement circuit that includes:
a first switch configured to be connected to a positive electrode of a battery;
a second switch configured to be connected to a negative electrode of the battery;
detection resistances that are connected in series between the first switch and the second switch;
capacitors that are connected in parallel to the detection resistances;
a measurement circuit that measures a voltage applied to the detection resistances; and
a controller that controls the first switch and the second switch, the method comprising the steps of:
(a) performing, by the controller, at least two measurement processes of
(i) a first measurement process in which (1) the first switch is turned on and the second switch is turned off to form a first series-connected circuit consisting of the battery, one of the detection resistances, and an insulation member on a negative electrode side of the battery that comes into electrical contact with the negative electrode of the battery, and (2) an insulation resistance of the insulation member on the negative electrode side is calculated based on a first voltage measured by the measurement circuit,
(ii) a second measurement process in which (1) the first switch is turned off and the second switch is turned on to form a second series-connected circuit consisting of the battery, one of the detection resistances, and an insulation member on a positive electrode side of the battery that comes into electrical contact with the positive electrode of the battery, and (2) an insulation resistance of the insulation member on the positive electrode side is calculated based on a second voltage measured by the measurement circuit, and
(iii) a third measurement process in which (1) the first switch and the second switch are turned off, and (2) an offset voltage is calculated based on a third voltage measured by the measurement circuit; and
(b) detecting, by the controller, failures of the capacitors based on a change in the voltage measured by the measurement circuit after switching from one to an other of the measurement processes.