Broad-band low-inductance cables for making Kelvin connections to electrochemical cells and batteries

• US 7,106,070 B2
• Filed: 07/22/2004
• Issued: 09/12/2006
• Est. Priority Date: 07/22/2004
• Status: Active Grant

• Current Assignee: Midtronics Incorporated
• Original Assignee: Midtronics Incorporated
• Inventors: Bertness, Kevin I., Champlin, Keith S.
• Primary Examiner(s): Lee, Diane
• Assistant Examiner(s): Zhu, John
• Application Number:
  US10/896,835
• Publication Number:
  US 20060017447A1
• Time in Patent Office: 782 Days
• Field of Search: 324/538, 324/628, 333/12
• US Class Current: 324/538
• CPC Class Codes: G01R 31/385 Arrangements for measuring battery or accumulator variables for monitoring G01R31/382

Abstract

A broad-band technique for reducing the distributed inductance of a four-conductor Kelvin cable is disclosed. A special inductance-canceling cable section is connected in tandem with the cable section contacting the cell/battery. Connections between the two cable sections are transposed such that conductors in each conductor pair of the canceling section connect to current-carrying and voltage-sensing conductors from different conductor pairs in the contacting section. The canceling section thereby exhibits a distributed negative mutual inductance between its current-carrying and voltage-sensing conductors that can effectively cancel the distributed positive mutual inductance introduced by the contacting section.

In one embodiment, conductor pairs comprise pairs of insulated wires which may be twisted together. In other disclosed embodiments, conductor pairs comprise shielded coaxial cables.

Claims

1. A low-inductance cable for implementing Kelvin connections to positive and negative terminals of an electrochemical cell or battery comprising:

a first cable section adapted to couple to a positive terminal with a first current-carrying conductor and a first voltage sensing conductor and to couple to a negative terminal with a second current-carrying conductor and a second voltage-sensing conductor, said second current-carrying and voltage-sensing conductors spaced apart from said first current-carrying and voltage-sensing conductors,

a second cable section comprising a third current-carrying conductor, a third voltage-sensing conductor, a fourth current-carrying conductor, and a fourth voltage-sensing conductor, said fourth current-carrying and voltage sensing conductors spaced apart from said third current-carrying and voltage-sensing conductors; and

,

a cable junction interposed between said first cable section and said second cable section, said cable junction transposing connections by interconnecting said first and fourth current-carrying conductors, said second and third current-carrying conductors, said first and third voltage-sensing conductors, and said second and fourth voltage-sensing conductors.

2. The low-inductance cable of claim 1 wherein said first current-carrying and voltage-sensing conductors, said second current-carrying and voltage-sensing conductors, said third current-carrying and voltage-sensing conductors, and said fourth current-carrying and voltage-sensing conductors comprise four pairs of insulated wires.

3. The low-inductance cable of claim 2 wherein wires of each said pair are twisted together.

4. The low-inductance cable of claim 1 wherein said first current-carrying and voltage-sensing conductors, said second current-carrying and voltage-sensing conductors, said third current-carrying and voltage-sensing conductors, and said fourth current-carrying and voltage-sensing conductors comprise four shielded coaxial cables.

5. The low-inductance cable of claim 4 wherein current-carrying and voltage-sensing conductors of said first cable section couple through a distributed mutual inductance given by equation (6)

$M_1=(\frac{{\mu }_{}}{}$

0 ·

L 1 π

) ·

{ ( 1 + ( 2 ·

L 1 W 1 ) ·

( d o 4 ·

L 1 ) 1 - ( W 1 2 ·

L 1 ) 2 ) ·

ln ⁡

( 1 + 1 - ( W 1 2 ·

L 1 ) 2 ( 2 ·

L 1 W 1 ) ·

( d o 4 ·

L 1 ) ) - 1 }

and current-carrying and voltage-sensing conductors of said second cable section couple through a distributed mutual inductance given by equation (7)

$M_2=\left(\frac{-{\mathrm{\mu <br><br>}}_0·<br><br>L_2}{\mathrm{\pi <br><br>}}\right)·<br><br>\ln <br><br>\left(1+\frac{2·<br><br>W_2}{d_o}\right).$

6. A connecting cable for providing Kelvin connections to a positive terminal and a negative terminal of an electrochemical cell or battery comprising:

a first cable section adapted to couple to said positive terminal with first and second conductors and to couple to said negative terminal with third and fourth conductors, said third and fourth conductors spaced apart from said first and second conductors,

a second cable section comprising fifth, sixth, seventh, and eighth conductors, said seventh and eighth conductors spaced apart from said fifth and sixth conductors,

a third cable section comprising ninth, tenth, eleventh, and twelfth conductors, said eleventh and twelfth conductors spaced apart from said ninth and tenth conductors,

a first cable junction interposed between said first cable section and said second cable section, said first cable junction transposing connections by interconnecting said first and eighth conductors, said second and sixth conductors, said third and seventh conductors, and said fourth and fifth conductors; and

a second cable junction interposed between said second cable section and, said third cable section, said second cable junction transposing connections by interconnecting said fifth and tenth conductors, said sixth and eleventh conductors, said seventh and twelfth conductors, and said eighth and ninth conductors.

7. The connecting cable of claim 6 wherein said first and second conductors, said third and fourth conductors, said fifth and sixth conductors, and said seventh and eighth conductors comprise four pairs of insulated wires.

8. The connecting cable of claim 7 wherein insulated wires of each said pair are twisted together.

9. The connecting cable of claim 6 wherein said first and second conductors, said third and fourth conductors, said fifth and sixth conductors, and said seventh and eighth conductors comprise conductors of four shielded coaxial cables.

10. The connecting cable of claim 6 wherein said ninth and tenth conductors and said eleventh and twelfth conductors comprise two pairs of twisted insulated wires.

11. The connecting cable of claim 6 wherein said ninth and tenth conductors and said eleventh and twelfth conductors comprise conductors of two shielded coaxial cables.

12. The connecting cable of claim 9 wherein coaxial cable shields couple to coaxial cable center conductors through distributed mutual inductances given by equation (6)

$M_1=(\frac{{\mu }_{}}{}$

0 ·

L 1 π

) ·

{ ( 1 + ( 2 ·

L 1 W 1 ) ·

( d o 4 ·

L 1 ) 1 - ( W 1 2 ·

L 1 ) 2 ) ·

ln ⁡

( 1 + 1 - ( W 1 2 ·

L 1 ) 2 ( 2 ·

L 1 W 1 ) ·

( d o 4 ·

L 1 ) ) - 1 }

in cable section 1 and by equation (7)

$M_2=\left(\frac{-{\mathrm{\mu <br><br>}}_0·<br><br>L_2}{\mathrm{\pi <br><br>}}\right)·<br><br>\ln <br><br>\left(1+\frac{2·<br><br>W_2}{d_o}\right).$

in cable section 2.

13. The connecting cable of claim 11 wherein coaxial cable shields couple to coaxial cable center conductors through distributed mutual inductance given by equation (7)

$M_2=(\frac{-{\mu }_{}}{}$

0 ·

L 2 π

) ·

ln ⁡

( 1 + 2 ·

W 2 d o ) .

14. A cable for implementing Kelvin connections to first and second terminals of an electrochemical cell or battery comprising:

a first cable section adapted to couple to said first terminal with a conductor pair comprising a current-carrying conductor and a voltage-sensing conductor and to couple to said second terminal with another conductor pair comprising a current-carrying conductor and a voltage-sensing conductor,

a second cable section comprising two spaced-apart conductor pairs, each said pair comprising a current-carrying conductor and a voltage-sensing conductor; and

,

a cable junction interconnecting conductors of said first and second cable sections, said cable junction transposing connections such that conductors in each pair in said first cable section couple to conductors in different pairs in said second cable section.

15. The cable of claim 14 wherein said conductor pairs in said first and second cable sections comprise pairs of insulated wires.

16. The cable of claim 15 wherein insulated wires of each said pair are twisted together.

17. The cable of claim 14 wherein said conductor pairs in said first and second cable sections comprise shielded coaxial cables.

18. The cable of claim 17 wherein current-carrying conductors couple to voltage-sensing conductors in said first cable section through distributed mutual inductance given by equation (6)

$M_1=(\frac{{\mu }_{}}{}$

0 ·

L 1 π

) ·

{ ( 1 + ( 2 ·

L 1 W 1 ) ·

( d o 4 ·

L 1 ) 1 - ( W 1 2 ·

L 1 ) 2 ) ·

ln ⁡

( 1 + 1 - ( W 1 2 ·

L 1 ) 2 ( 2 ·

L 1 W 1 ) ·

( d o 4 ·

L 1 ) ) - 1 }

and current-carrying conductors couple to voltage-sensing conductors in said second cable section through distributed mutual inductance given by equation (7)

$M_2=\left(\frac{-{\mathrm{\mu <br><br>}}_0·<br><br>L_2}{\mathrm{\pi <br><br>}}\right)·<br><br>\ln <br><br>\left(1+\frac{2·<br><br>W_2}{d_o}\right).$

19. A low-inductance cable for implementing Kelvin connections to first and second terminals of an electrochemical cell or battery comprising:

a first cable section adapted to couple to said first terminal with one pair of conductors and to couple to said second terminal with another pair of conductors,

a second cable section comprising two spaced-apart pairs of conductors,

a third cable section comprising two spaced-apart pairs of conductors,

a first cable junction interconnecting conductors of said first and second cable sections, said first cable junction transposing connections such that conductors in each pair in said first cable section couple to conductors in different pairs in said second cable section; and

,

a second cable junction interconnecting conductors of said second and third cable sections, said second cable junction transposing connections such that conductors in each pair in said second cable section couple to conductors in different pairs in said third cable section.

20. The low-inductance cable of claim 19 wherein said pairs of conductors in said first and second cable sections comprise pairs of insulated wires.

21. The low-inductance cable of claim 20 wherein wires in each said pair are twisted together.

22. The low-inductance cable of claim 19 wherein said pairs of conductors in said first and second cable sections comprise shielded coaxial cables.

23. The low-inductance cable of claim 19 wherein said pairs of conductors in said third cable section comprise pairs of insulated wires twisted together.

24. The low-inductance cable of claim 19 wherein said pairs of conductors in said third cable section comprise shielded coaxial cables.

25. The low-inductance cable of claim 22 wherein mutual inductance coupling between coaxial cable shields and center-conductors is given by equation (6)

$M_1=(\frac{{\mu }_{}}{}$

0 ·

L 1 π

) ·

{ ( 1 + ( 2 ·

L 1 W 1 ) ·

( d o 4 ·

L 1 ) 1 - ( W 1 2 ·

L 1 ) 2 ) ·

ln ⁡

( 1 + 1 - ( W 1 2 ·

L 1 ) 2 ( 2 ·

L 1 W 1 ) ·

( d o 4 ·

L 1 ) ) - 1 }

in said first section and by equation (7)

$M_2=\left(\frac{-{\mathrm{\mu <br><br>}}_0·<br><br>L_2}{\mathrm{\pi <br><br>}}\right)·<br><br>\ln <br><br>\left(1+\frac{2·<br><br>W_2}{d_o}\right).$

in said second section.

26. The low-inductance cable of claim 24 wherein mutual inductance coupling between coaxial cable shields and center-conductors is given by equations (7)

$M_2=(\frac{-{\mu }_{}}{}$

0 ·

L 2 π

) ·

ln ⁡

( 1 + 2 ·

W 2 d o ) .

in said third section.