Device for measuring a battery current

• US 9,360,500 B2
• Filed: 09/20/2012
• Issued: 06/07/2016
• Est. Priority Date: 09/23/2011
• Status: Active Grant

• Current Assignee: Continental Automotive GmbH (Continental AG)
• Original Assignee: Continental Automotive GmbH (Continental AG)
• Inventors: Schramme, Martin, Graf, Hans-Michael
• Primary Examiner(s): Phan, Huy Q
• Assistant Examiner(s): FORTICH, ALVARO E
• Application Number:
  US14/346,468
• Publication Number:
  US 20140300347A1
• Time in Patent Office: 1,356 Days
• US Class Current: 1/1
• CPC Class Codes: G01R 1/203 Resistors used for electric measuring, e.g. decade resistors standards, resistors for comparators, series resistors, shunts resistors in general H01C; microwave or radiowave terminations H01P1/26; coupling devices H01R
• CPC Class Codes: G01R 31/374 with means for correcting the measurement for temperature or ageing
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• CPC Class Codes: H02J 7/007192 in response to temperature

Abstract

The present invention relates to a device for measuring a battery current of a battery. The device has a measuring distance, over which the entire battery current to be measured flows during the measurement. A measuring device measures a voltage drop across the measuring distance. On the basis of the measured voltage drop and a resistance of the measuring distance, a current determining device determines the battery current, wherein the measuring distance is formed by at least part of a cable with a temperature-dependent resistor.

Claims

1. A device for measuring a battery current of a battery of a vehicle, comprising

a measurement path, including a thermistor via which a total battery current to be measured flows during the measurement,

a measuring apparatus for measuring a voltage drop across the thermistor, and

a current determination apparatus for determining the battery current on the basis of the measured voltage drop;

and

a resistance compensation apparatus;

generating and applying a measurement current to the thermistor,

determining a change in resistance of the thermistor in response to the measurement current,

determining a compensation current based on the change in resistance, and

applying the compensation current to the thermistor.

2. The device as claimed in claim 1, wherein measurement path includes either a grounding cable, which connects a negative pole of the battery to an electrical conductor, to a body of the vehicle, to which conductor the grounding point of consumers are connected, or a connecting cable, which is arranged at a positive pole of the battery.

3. The device as claimed in claim 1, wherein the device is designed to multiplex a predetermined measurement current along the measurement path.

4. The device as claimed in claim 3, wherein the device is designed to implement the multiplexing by at least one method from the group consisting of space-division multiplexing methods, frequency-division multiplexing methods, code-division multiplexing methods and time-division multiplexing methods.

5. The device as claimed in claim 1, wherein a compensation cable runs parallel to a cable of the measurement path and is thermally coupled to the cable, wherein a temperature dependence of the resistance of the cable and of the compensation cable is substantially identical.

6. The device as claimed in claim 1, further comprising a multiplexer for multi-plexing the predetermined measurement current over the measurement path and a demultiplexer for isolating the measurement current from the battery current.

7. The device as claimed in claim 6, wherein the demultiplexer is configured as a filter or a lock-in amplifier.

8. The device as claimed in claim 6, further comprising a frequency generator for generating a predetermined measurement current in the form of an alternating current and/or a code generator for generating a predetermined measurement current with a modulated code.

9. The device as claimed in claim 1, further comprising a switch for ensuring that, in a first phase, only the battery current and, in a second phase, additionally a predetermined measurement current flows via the measurement path.

10. The device as claimed in claim 1, wherein the measuring apparatus is connected to a cable of the measurement path by a measurement cable and a further electrical connection.

11. A vehicle comprising a battery and a device for measuring a battery current of a battery of a vehicle, comprising

a measurement path, including a thermistor via which a total battery current to be measured flows during the measurement,

a measuring apparatus for measuring a voltage drop across the thermistor, and

a current determination apparatus for determining the battery current on the basis of the measured voltage drop;

and

a resistance compensation apparatus;

generating and applying a measurement current to the thermistor,

determining a change in resistance of the thermistor in response to the measurement current,

determining a compensation current based on the change in resistance, and

applying the compensation current to the thermistor.