Insulation resistance measuring device and method capable of rapidly measuring insulation resistance

{
  "publication_number": "US2017016951A1",
  "country": "US",
  "kind": "A1",
  "title": "Insulation resistance measuring device and method capable of rapidly measuring insulation resistance",
  "abstract": "Disclosed are insulation resistance measuring device and method that are capable of rapidly and accurately calculating insulation resistance, despite parasitic capacitor components present in a battery pack.",
  "claims": [
    "1. An insulation resistance measuring device, comprising: a positive electrode test resistor connected to a positive electrode node of a battery assembly; a negative electrode test resistor connected to a negative electrode node of the battery assembly; a switch unit connecting the positive electrode test resistor and the negative electrode test resistor to the positive electrode node and the negative electrode node of the battery assembly respectively such that a certain circuit is formed; a switch control unit configured to control the switch unit; a voltage measurement unit configured to measure a first voltage applied to the positive electrode test resistor and a second voltage applied to the negative electrode test resistor; and a voltage estimation unit configured such that, after the certain circuit is formed, the voltage estimation unit under controlling of the switch control unit reads at least one voltage among the first voltage and the second voltage measured at the voltage measurement unit for at least two cycles according to a predetermined cycle, and estimates a final convergence value of at least one voltage among the first voltage and the second voltage by using the read voltage. 2. The insulation resistance measuring device of claim 1, wherein the switch unit comprises a first switch provided on a first line connecting the positive electrode node of the battery assembly to the positive electrode test resistor to be selectively turned on or off; and a second switch provided on a second line connecting the negative electrode node of the battery assembly to the negative electrode test resistor to be selectively turned on or off. 3. The insulation resistance measuring device of claim 2, wherein the certain circuit is any one of a first circuit in which the first switch and the second switch are turned on, a second circuit in which the first switch is turned on and the second switch is turned off, a third circuit in which the first switch is turned off and the second switch is turned on, and a fourth circuit in which the first switch and the second switch are turned off. 4. The insulation resistance measuring device of claim 3, wherein, after the second circuit is formed, the voltage estimation unit reads the first voltage measured at the voltage measurement unit for at least two cycles according to the predetermined cycle, calculates a first estimate value using the read voltage, and estimates that the first estimate value is a final convergence value of the first voltage. 5. The insulation resistance measuring device of claim 4, wherein, after the third circuit is formed, the voltage estimation unit reads the second voltage measured at the voltage measurement unit for at least two cycles according to the predetermined cycle, calculates a second estimate value using the read voltage, and estimates that the second estimate value is a final convergence value of the second voltage. 6. The insulation resistance measuring device of claim 5, wherein the insulation resistance measuring device further comprises an insulation resistance calculation unit configured to calculate an insulation resistance of a positive electrode side of the battery assembly and an insulation resistance of a negative electrode side of the battery assembly, using a second circuit equation that is a circuit equation about the second circuit, a third circuit equation that is a circuit equation about the third circuit, and the first estimate value and the second estimate value. 7. The insulation resistance measuring device of claim 6, wherein the insulation resistance calculation unit calculates the insulation resistance of the positive electrode side of the battery assembly and the insulation resistance of the negative electrode side of the battery assembly by substituting the first estimate value into the second circuit equation, substituting the second estimate value into the third circuit equation, and then finding a solution of simultaneous quadratic equations composed of the second circuit equation and the third circuit equation. 8. The insulation resistance measuring device of claim 1, wherein the voltage estimation unit reads at least one voltage among the first voltage and the second voltage measured at the voltage measurement unit for at least three cycles according to a predetermined cycle, and estimates a final convergence value of at least one voltage among the first voltage and the second voltage by using the read voltage. 9. The insulation resistance measuring device of claim 8, wherein the voltage estimation unit estimates the final convergence value with a first read voltage read in a first cycle, a second read voltage read in a second cycle, and a third read voltage read in a third cycle, using the equation below: y f = y 2 2 - y 1 * y 3 2 * y 2 - y 1 - y 3 where, yf=final convergence value, y 1 =first read voltage, y 2 =second read voltage, y 3 =third read voltage. 10. The insulation resistance measuring device of claim 1, wherein the insulation resistance measuring device further comprises a positive electrode distribution resistor provided on the first line, and a negative electrode distribution resistor provided on the second line. 11. The insulation resistance measuring device of claim 1, wherein the insulation resistance measuring device further comprises a DC power supply provided on the second line. 12. The insulation resistance measuring device of claim 11, wherein a magnitude of voltage outputted from the DC power supply is set such that the second voltage measured by the voltage measurement unit is a positive value. 13. A battery pack comprising the insulation resistance measuring device of claim 1. 14. An electric vehicle comprising the insulation resistance measuring device of claim 1. 15. An insulation resistance measuring method, comprising steps of: preparing an insulation resistance measuring device comprising a positive electrode test resistor connected to a positive electrode node of a battery assembly, a negative electrode test resistor connected to a negative electrode node of the battery assembly, a switch unit connecting the positive electrode test resistor and the negative electrode test resistor to the positive electrode node and the negative electrode node of the battery assembly respectively such that a certain circuit is formed, and a voltage measurement unit configured to measure a first voltage applied to the positive electrode test resistor and a second voltage applied to the negative electrode test resistor; controlling the switch unit to form a certain circuit; after the certain circuit is formed, reading at least one voltage among the first voltage and the second voltage for at least two cycles according to a predetermined cycle; and estimating a final convergence value of the at least one voltage among the first voltage and the second voltage using the voltage read in the reading step. 16. The insulation resistance measuring method of claim 15, wherein the switch unit comprises a first switch provided on a first line connecting the positive electrode node of the battery assembly to the positive electrode test resistor to be selectively turned on or off; and a second switch provided on a second line connecting the negative electrode node of the battery assembly to the negative electrode test resistor to be selectively turned on or off. 17. The insulation resistance measuring method of claim 16, wherein the certain circuit is any one of a first circuit in which the first switch and the second switch are turned on, a second circuit in which the first switch is turned on and the second switch is turned off, a third circuit in which the first switch is turned off and the second switch is turned on, and a fourth circuit in which the first switch and the second switch are turned off. 18. The insulation resistance measuring method of claim 17, wherein the step of forming the certain circuit comprises forming the second circuit, the reading step comprises, after the second circuit is formed, reading the first voltage for at least two cycles according to the predetermined cycle, and the estimating step comprises calculating a first estimate value with the voltage read in the reading step, and estimating that the first estimate value is a final convergence value of the first voltage. 19. The insulation resistance measuring method of claim 18, wherein the step of forming the certain circuit comprises forming the third circuit, the reading step comprises, after the third circuit is formed, reading the second voltage for at least two cycles according to the predetermined cycle, and the estimating step comprises calculating a second estimate value with the voltage read in the reading step, and estimating that the second estimate value is a final convergence value of the second voltage, wherein the steps of forming the third circuit, reading the second voltage, and estimating that the second estimate value is the final convergence value of the second voltage are performed prior to, or subsequent to the steps of forming the second circuit, measuring the first voltage, and estimating that the first estimate value is the final convergence value of the first voltage. 20. The insulation resistance measuring method of claim 19, wherein the insulation resistance measuring method further comprises calculating an insulation resistance of a positive electrode side of the battery assembly and an insulation resistance of a negative electrode side of the battery assembly, using a second circuit equation that is a circuit equation about the second circuit, a third circuit equation that is a circuit equation about the third circuit, and the first estimate value and the second estimate value. 21. The insulation resistance measuring method of claim 20, wherein the insulation resistance calculating step comprises calculating the insulation resistance of the positive electrode side of the battery assembly and the insulation resistance of the negative electrode side of the battery assembly by substituting the first estimate value into the second circuit equation, substituting the second estimate value into the third circuit equation, and then finding a solution of simultaneous quadratic equations composed of the second circuit equation and the third circuit equation. 22. The insulation resistance measuring method of claim 15, wherein the reading step comprises reading at least one voltage among the first voltage and the second voltage for at least three cycles according to a predetermined cycle, and the estimating step comprises estimating a final convergence value of the at least one voltage among the first voltage and the second voltage using the read voltage. 23. The insulation resistance measuring method of claim 22, wherein the estimating step comprises estimating the final convergence value with a first read voltage read in a first cycle, a second read voltage read in a second cycle, and a third read voltage read in a third cycle, using the equation below: y f = y 2 2 - y 1 * y 3 2 * y 2 - y 1 - y 3 where, yf=final convergence value, y 1 =first read voltage, y 2 =second read voltage, y 3 =third read voltage."
  ],
  "cpc": [
    "G01R 31/1236",
    "G01R 1/203",
    "G01R 1/206",
    "G01R 19/16542",
    "G01R 27/025",
    "G01R 31/12",
    "G01R 31/1263",
    "G01R 31/36",
    "G01R 31/364",
    "G01R 31/3655",
    "G01R 31/3662",
    "G01R 31/3696",
    "G01R 31/389",
    "G01R 31/396",
    "H01M 10/48",
    "H01M 50/569",
    "Y02E 60/10"
  ],
  "assignees": [
    "LG CHEMICAL LTD"
  ],
  "filing_date": "2015-10-02",
  "publication_date": "2017-01-19",
  "priority_date": "2014-10-02",
  "application_number": "US-201515124887-A",
  "family_id": "55630996",
  "citations": [
    "US2008054907A1",
    "US2009289640A1",
    "US2010156426A1",
    "US2013176041A1"
  ]
}