Device and method for the detection of a charging voltage

• US 20030214268A1
• Filed: 04/14/2003
• Published: 11/20/2003
• Est. Priority Date: 04/15/2002
• Status: Active Grant

• Current Assignee: Friwo Gerätebau GmbH
• Original Assignee: Friwo Gerätebau GmbH
• Inventors: Breuch, Georg, Kubacki, Zbigniew
• Granted Patent: US 6,906,498 B2
• Time in Patent Office: Days
• US Class Current: 320/128
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries

Abstract

The present invention relates to a device and a method for the detection of a charging voltage of at least one rechargeable battery comprising a voltage converter for converting the charging voltage of the at least one rechargeable battery into a voltage signal, an analog/digital converter for converting the voltage signal of the voltage converter into a digital signal, and an evaluation and control device for evaluating the digital signal of the analog/digital converter as well as for controlling the charging process of the at least one rechargeable battery on the basis of the evaluation of the digital signal of the analog/digital converter. The voltage converter comprises an amplifier circuit with a variable gain controlled by at least one control output terminal of the evaluation and control device such that the gain applied for the generation of the voltage signal is adjusted to the input voltage range of the analog/digital converter according to a transfer function.

Claims

1. Device for the detection of a charging voltage (205) of at least one rechargeable battery comprising:

a voltage converter (202) for converting the charging voltage (205) of the at least one rechargeable battery (201) into a voltage signal (206),

an analog/digital converter (203) for converting the voltage signal (206) of the voltage converter (202) into a digital signal, and

an evaluation and control device (203) for evaluating the digital signal of the analog/digital converter (203) as well as for controlling the charging process of the at least one rechargeable battery (201) on the basis of the evaluation of the digital signal of the analog/digital converter (203),

wherein the voltage converter (202) comprises an amplifier circuit with a variable gain controlled by at least one control output terminal (207) of the evaluation and control device (203) such that the gain applied for the generation of the voltage signal (206) is adjusted to the input voltage range of the analog/digital converter (203) according to a transfer function.

2. Device for the detection of a charging voltage (205) according to claim 1, characterized in that the amplifier circuit is formed of an operation amplifier circuit.

3. Device for the detection of a charging voltage (205) according to claim 2, characterized in that the gain is controlled by resistors connected by the evaluation and control device (203).

4. Device for the detection of a charging voltage (205) according to claim 3, characterized in that the adjustment of the voltage signal (206) of the voltage converter (202) to the input voltage range of the analog/digital converter (203) is divided into a number of ranges with a constant gain in response to the maximum number of accumulator cells (201) to be charged, the number of which is defined such that, given both a minimum and a maximum number of batteries (201) to be charged, the evaluation and control device (203) evaluates, with the aid of the analog/digital converter (203), the voltage changes of the voltage signal (206) of the voltage converter (202) with a predetermined accuracy so as to guarantee a defined evaluation accuracy over the entire charging voltage range.

5. Device for the detection of a charging voltage (205) according to claim 4, characterized in that the ranges for the adjustment of the voltage signal (206) of the voltage converter (202) to the input voltage range of the analog/digital converter (203) overlap so as to guarantee a continuous transition between two successive ranges.

6. Device for the detection of a charging voltage (205) according to claim 4, characterized in that the adjustment of the voltage signal (206) of the voltage converter (202) to the input voltage range of the analog/digital converter (203) takes place by the step-wise adjustment of the duty cycle of the pulse width modulation circuit such that the voltage signal (206) is projected in a certain input voltage range of the analog/digital converter (203), so that a defined evaluation accuracy is guaranteed.

7. Device for the detection of a charging voltage (205) according to claim 2, characterized in that the gain is controlled by means of pulse width modulation.

8. Device for the detection of a charging voltage (205) according to claim 7, characterized in that the adjustment of the voltage signal (206) of the voltage converter (202) to the input voltage range of the analog/digital converter (203) is divided into a number of ranges with a constant gain in response to the maximum number of accumulator cells (201) to be charged, the number of which is defined such that, given both a minimum and a maximum number of batteries (201) to be charged, the evaluation and control device (203) evaluates, with the aid of the analog/digital converter (203), the voltage changes of the voltage signal (206) of the voltage converter (202) with a predetermined accuracy so as to guarantee a defined evaluation accuracy over the entire charging voltage range.

9. Device for the detection of a charging voltage (205) according to claim 8, characterized in that the ranges for the adjustment of the voltage signal (206) of the voltage converter (202) to the input voltage range of the analog/digital converter (203) overlap so as to guarantee a continuous transition between two successive ranges.

10. Device for the detection of a charging voltage (205) according to claim 7, characterized in that the adjustment of the voltage signal (206) of the voltage converter (202) to the input voltage range of the analog/digital converter (203) takes place by the step-wise adjustment of the duty cycle of the pulse width modulation circuit such that the voltage signal (206) is projected in a certain input voltage range of the analog/digital converter (203), so that a defined evaluation accuracy is guaranteed.

11. Device for the detection of a charging voltage (205) according to claim 1, characterized in that the evaluation and control device (203) is formed of a microcontroller, a programmable microprocessor or an ASIC (Application Specific Integrated Circuit).

12. Device for the detection of a charging voltage (205) according to claim 1, characterized in that the analog/digital converter is integrated in the evaluation and control device (203).

13. Device for the detection of a charging voltage (205) according to claim 1, characterized in that the microcontroller (203) includes at least one control output terminal (207) by which the resistors or the pulse width modulation for the gain are connected directly or indirectly.

14. Device for the detection of a charging voltage (205) according to claim 1, characterized in that the analog/digital converter is an 8 bit analog/digital converter and the microcontroller is an 8 bit microcontroller.

15. Charger comprising a device for the detection of a charging voltage (205) according to claim 1.

16. Method of detecting a charging voltage (205) of at least one rechargeable battery (201), wherein

the charging voltage (205) of the at least one rechargeable battery (201) is converted by means of a voltage converter (202) into a voltage signal (206),

the voltage signal (206) of the voltage converter (202) is converted by means of an analog/digital converter (203) into a digital signal, and

an evaluation and control device (203) evaluates the digital signal of the analog/digital converter (203) for controlling the charging process of the at least one rechargeable battery (201) on the basis of the evaluation of the digital signal,

wherein the gain of the voltage converter (202 applied for the generation of the voltage signal (206) is variably amplified by an amplifier circuit so as to adjust the voltage signal (206) to the input voltage range of the analog/digital converter (203).

17. Method of detecting the charging voltage (205) according to claim 16, characterized in that the adjustment of the voltage signal (206) of the voltage converter (202) to the input voltage range of the analog/digital converter (203) is divided into a number of ranges with a constant gain in response to the maximum number of accumulator cells (201) to be charged, the number of which is defined such that, given both a minimum and a maximum number of batteries (201) to be charged, the evaluation and control device (203) evaluates, with the aid of the analog/digital converter (202), the voltage changes of the voltage signal (206) of the voltage converter (203) with a predetermined accuracy so as to guarantee a defined evaluation accuracy over the entire charging voltage range.

18. Method of detecting the charging voltage (205) according to claim 16, characterized in that the ranges for the adjustment of the voltage signal (206) of the voltage converter (202) to the input voltage range of the analog/digital converter (203) overlap so as to guarantee a continuous transition between two successive ranges.