Estimation of the insulation resistance between a motor vehicle battery and the earth

Patent metadata

Field	Value
Publication number	US-2016334452-A1
Application number	US-201415101741-A
Country	US
Kind code	A1
Filing date	Dec 2, 2014
Priority date	Dec 4, 2013
Publication date	Nov 17, 2016
Grant date	—

Abstract

A method for estimating an insulation resistance between a point of a high-voltage circuit including a high-voltage motor vehicle battery and a ground of the vehicle includes measuring a voltage value at terminals of a measurement circuit that includes a capacitive element connected to the battery and calculating a standard deviation value based on the measured voltage value and based on a theoretical voltage value estimated from a model of the measurement circuit. The model is a function of a capacitance value of the capacitive element. The method also includes calculating an averaged deviation value from the standard deviation value and previous deviation values and estimating an updated insulation resistance value in accordance with the averaged deviation value.

First claim

1 - 11 . (canceled)

12 . A method for estimating an insulation resistance between a point of a high-voltage circuit including a high-voltage motor vehicle battery and a ground of said vehicle, the method comprising:
(a) measuring a voltage value at terminals of a measurement circuit, said measurement circuit comprising a capacitive element connected to the battery; (b) calculating a standard deviation value based on the measured voltage value, and based on a theoretical voltage value estimated from a model of the measurement circuit, said model being a function of a capacitance value of the capacitive element; (c) calculating an averaged deviation value from the standard deviation value and previous deviation values; and (d) estimating an updated insulation resistance value in accordance with said averaged deviation value.

13 . The method according to claim 12 , wherein
steps (a), (b), (c) and (d) are regularly reiterated, and the insulation resistance value updated during a standard iteration is used in the next iteration for the model of the measurement circuit.

14 . The method according to claim 12 , wherein, during step (b), the standard deviation is calculated by taking the difference between the measured voltage value and the theoretical voltage value, the sign of said difference being a function of an input signal value of the measurement circuit.

15 . The method according to claim 12 , wherein, during step (c), the averaged deviation value is obtained by adding a previous averaged deviation value to the standard deviation value.

16 . The method according to claim 12 , wherein step (d) for estimating the updated insulation resistance value is a function of a linear combination of the standard deviation value and the averaged deviation value calculated in step (c).

17 . The method according to claim 16 , wherein, during step (d), the updated insulation resistance value is estimated according to the formula:
R isol ( n )= K variable [R isol ( n− 1)]( K p ε+K i ∫ε)
wherein n corresponds to the standard iteration (n−1) corresponding to the immediately preceding iteration, R isol (n) represents the insulation resistance value updated during the standard iteration, R isol (n−1) represents a previous insulation resistance value, ε represents the standard deviation value, K i and K p represent predetermined constants, and K variable represents a parameter value selected as a function of the previous insulation resistance value.

18 . The method according to claim 12 , further comprising
(e) according to the insulation resistance value updated in step (d), generating an alarm signal to prevent detection of an insulation fault.

19 . A device for estimating an insulation resistance between a point of a high-voltage circuit including a high-voltage motor vehicle battery and a ground of said vehicle, the device comprising:
receiving means to receive a voltage value measured at terminals of a measurement circuit, said measurement circuit comprising a capacitive element connected to the battery; a memory to store a model of the measurement circuit, said model being a function of a capacitance value of the capacitive element; and processing means arranged to calculate a standard deviation value based on the measured voltage value and based on a theoretical voltage value estimated from the model of the measurement circuit, in order to calculate a deviation value averaged from the standard deviation value and a plurality of previous deviation values, and to estimate an insulation resistance value updated according to said averaged deviation value.

20 . A system for estimating an insulation resistance between a point of a high-voltage circuit including a high-voltage motor vehicle battery and a ground of said vehicle, the system comprising:
a measurement circuit comprising a capacitive component electrically connected to the battery; and the estimation device according to claim 19 , the estimation device being electrically connected to an input of the measurement circuit, and to a measurement terminal of the measurement circuit.

21 . The system according to claim 20 , wherein the measurement circuit comprises:
an input resistor including a terminal that is electrically connected to the input of the measurement circuit; and a low-pass filtering part comprising a resistive element and a capacitive element.

22 . A motor vehicle, comprising:
a battery capable of rotating front and/or rear wheels of the vehicle; and the system according to claim 20 .

Assignees

• Renault Sa
• Renault Sa

Inventors

• Mensler Michel
• Merienne Ludovic

Classifications

• G01R27/18

  Measuring resistance to earth {, i.e. line to ground} · CPC title

• G01R31/007 Primary

  using microprocessors or computers · CPC title

• G01R31/025

  Physics · mapped topic

• G01R31/52 Primary

  Testing for short-circuits, leakage current or ground faults · CPC title