Fault detection for battery chargers

• US 7,848,072 B2
• Filed: 05/01/2008
• Issued: 12/07/2010
• Est. Priority Date: 05/01/2008
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Rivalsi, Kenneth J., Paul, Christopher R., Cordes, Kevin, Riechel, Patrick
• Primary Examiner(s): Nguyen; Danny
• Application Number:
  US12/113,278
• Publication Number:
  US 20090273872A1
• Time in Patent Office: 950 Days
• Field of Search: 361/78, 361/9, 361/90, 361/93.1, 361/93.17, 320/116, 320/134, 320/135
• US Class Current: 361/93.1
• 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 19/16542 for batteries charge condition monitoring in G01R31/36
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• CPC Class Codes: H02H 7/18 for batteries; for accumulators
• CPC Class Codes: H02J 7/00304 Overcurrent protection

Abstract

A method of fault detection for battery chargers includes sensing a charge current applied to a battery with a resistive element. The method includes measuring a voltage across the resistive element. The method includes generating a trigger signal when the measured voltage across the resistive element exceeds a predetermined value. The method includes generating from the trigger signal an interrupt signal for a microprocessor. The method includes initiating an over-current handling routine in the microprocessor.

Claims

1. An apparatus comprising:

a plurality of battery charging stations;

a plurality of resistive elements wherein a resistive element is coupled to a battery charging station for sensing a charge current generated by the battery charging station;

a plurality of comparators wherein a given comparator is associated with a corresponding resistive element selected from the plurality of resistive elements, the given comparator has a first input coupled to a first terminal of the corresponding resistive element and has a second input coupled to a second terminal of the corresponding resistive element, and wherein the first terminal of the given comparator is coupled to a reference voltage;

a microprocessor having an interrupt input; and

wherein the plurality of comparators includes multiple comparators each having an output coupled to the interrupt input of the microprocessor.

2. The apparatus of claim 1, wherein

each comparator measures a voltage across a corresponding resistive element.

3. The apparatus of claim 1,

further comprising a plurality of differential amplifiers for measuring a voltage across a corresponding plurality of resistive elements.

4. The apparatus of claim 1,

further comprising a plurality of low pass filters for filtering a voltage across a corresponding plurality of resistive elements.

5. The apparatus of claim 1, wherein each resistive element senses a charge current generated by the battery charging station by

passing the charge current through each resistive element in the plurality of resistive elements.

6. The apparatus of claim 1,

wherein each battery charging station includes a first terminal coupled to a power source and a second terminal coupled to a common voltage through a corresponding resistive element.

7. The apparatus of claim 1,

wherein each battery charging station includes a first terminal coupled to a power source through a corresponding resistive element and a second terminal coupled to a common voltage.

8. The apparatus of claim 1, wherein at least one of the plurality of comparators is a Schmidt trigger.

9. The apparatus of claim 1, wherein at least one of the plurality of comparators is a differential amplifier.

10. The apparatus of claim 1, further comprising:

a plurality of capacitive elements, each capacitive element being coupled between the second input of a corresponding comparator and a common voltage.

11. The apparatus of claim 1, further comprising:

a plurality of low-pass filters, each low-pass filter being coupled between the second terminal of a corresponding resistive element and the second input of a corresponding comparator.

12. An apparatus comprising:

a plurality of battery charging stations;

a plurality of resistive elements wherein a resistive element is coupled to a battery charging station for sensing a charge current generated by the battery charging station;

a plurality of comparators wherein a given comparator is associated with a corresponding resistive element selected from the plurality of resistive elements, the given comparator has a first input coupled to a first terminal of the corresponding resistive element and has a second input coupled to a second terminal of the corresponding resistive element, and wherein the first terminal of the given comparator is coupled to a reference voltage;

a microprocessor;

a data bus that is configured to be polled by the microprocessor; and

wherein the plurality of comparators includes multiple comparators each having an output coupled to the data bus.

13. The apparatus of claim 12, wherein

each comparator measures a voltage across a corresponding resistive element.

14. The apparatus of claim 12,

further comprising a plurality of low pass filters for filtering a voltage across a corresponding plurality of resistive elements.

15. The apparatus of claim 12, wherein each resistive element senses a charge current generated by the battery charging station by

passing the charge current through each resistive element in the plurality of resistive elements.