Device and method for the detection of a charging voltage

• US 6,906,498 B2
• Filed: 04/14/2003
• Issued: 06/14/2005
• Est. Priority Date: 04/15/2002
• Status: Active Grant

• Current Assignee: Friwo Gerätebau GmbH
• Original Assignee: Friwo Gerätebau GmbH
• Inventors: Kubacki, Zbigniew, Breuch, Georg
• Primary Examiner(s): TIBBITS, PIA FLORENCE
• Application Number:
  US10/413,063
• Publication Number:
  US 20030214268A1
• Time in Patent Office: 792 Days
• Field of Search: 320/145, 320/148, 320/152, 320/156, 320/157, 320/160, 320/161, 320/162, 320/164, 320/DIG.21, 320/106, 324/433, 330/278
• US Class Current: 320/145
• 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
• CPC Class Codes: H02J 7/007182 in response to battery voltage

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 of a plurality of rechargeable batteries, the device comprising:

a voltage converter for converting the voltage of the rechargeable batteries 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 and for controlling the charging process of the at least one rechargeable battery based on the evaluation of the digital signal of the analog/digital converter,

wherein 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 an input voltage range of the analog/digital converter according to a transfer function, and

wherein the evaluation and control device is adapted to define a number of ranges, each range having a gain to adjust the voltage signal of the voltage converter to the input voltage range of the analog/digital converter, the gain being determined by a maximum number of rechargeable batteries the device is capable to charge and a predetermined minimum accuracy for the conversion of the voltage signal of the voltage converter into a digital signal, the evaluation and control device adapted to adjust the transfer function of the amplifier circuit for each of the ranges based on the number of rechargeable batteries to be charged and the predetermined minimum accuracy.

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

4. Device for the detection of a charging voltage according to claim 3, characterized in that the ranges for the adjustment of the voltage signal of the voltage converter to the input voltage range of the analog/digital converter overlap so as to guarantee a continuous transition between two successive ranges.

5. Device for the detection of a charging voltage according to claim 3, characterized in that the adjustment of the voltage signal of the voltage converter to the input voltage range of the analog/digital converter takes place by the step-wise adjustment of the duty cycle of a pulse width modulation circuit such that the voltage signal is projected in a certain input voltage range of the analog/digital converter, so that a predetermined accuracy is guaranteed.

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

7. Device for the detection of a charging voltage according to claim 6, characterized in that the ranges for the adjustment of the voltage signal of the voltage converter to the input voltage range of the analog/digital converter overlap so as to guarantee a continuous transition between two successive ranges.

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

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

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

11. Device for the detection of a charging voltage according to claim 1, wherein the evaluation and control device includes a microcontroller and characterized in that the microcontroller includes at least one control output terminal by which the resistors or the pulse width modulation for the gain are connected directly or indirectly.

12. Device for the detection of a charging voltage according to claim 1, wherein the evaluation and control device includes a microcontroller and characterized in that the analog/digital converter is an 8 bit analog/digital converter and the microcontroller is an 8 bit microcontroller.

13. Charger comprising a circuit for detection of a charging voltage of a plurality of rechargeable batteries, the circuit comprising:

a voltage converter for converting the charging voltage of the rechargeable batteries 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 and for controlling the charging process of the at least one rechargeable battery based on the evaluation of the digital signal of the analog/digital converter,

wherein 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 an input voltage range of the analog/digital converter according to a transfer function, and

wherein the evaluation and control device is adapted to define a number of ranges, each range having a gain to adjust the voltage signal of the voltage converter to the input voltage range of the analog/digital converter, the gain being determined by a maximum number of rechargeable batteries the device is capable to charge and a predetermined minimum accuracy for the conversion of the voltage signal of the voltage converter into a digital signal, the evaluation and control device adapted to adjust the transfer function of the amplifier circuit for each of the ranges based on the number of recharaeable batteries to be charged and the predetermined minimum accuracy.

14. Method of detecting a charging voltage of a plurality of rechargeable batteries, wherein

the voltage of the rechargeable batteries is converted by means of a voltage converter into a voltage signal,

the voltage signal of the voltage converter is converted by means of an analog/digital converter into a digital signal, and

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

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

wherein the evaluation and control device is adapted to define a number of ranges, each range having a gain to adjust the voltage signal of the voltage converter to the input voltage range of the analog/digital converter the gain being determined by a maximum number of rechargeable batteries the device is capable to charge and a predetermined minimum accuracy for the conversion of the voltage signal of the voltage converter into a digital signal, the evaluation and control device adapted to adjust the transfer function of the amplifier circuit for each of the ranges based on the number of rechargeable batteries to be charged and the predetermined minimum accuracy.

15. Method of detecting the charging voltage according to claim 14, characterized in that the ranges for the adjustment of the voltage signal of the voltage converter to the input voltage range of the analog/digital converter overlap so as to guarantee a continuous transition between two successive ranges.