Charging system for field devices

• US 20060244424A1
• Filed: 04/28/2006
• Published: 11/02/2006
• Est. Priority Date: 04/28/2005
• Status: Active Grant

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Nelson, Richard L.
• Granted Patent: US 7,560,907 B2
• Time in Patent Office: Days
• US Class Current: 322/37
• CPC Class Codes: H02J 15/00 Systems for storing electric energy mechanical systems therefor F01-F04; in chemical form H01M
• CPC Class Codes: H02J 7/34 Parallel operation in networks using both storage and other dc sources, e.g. providing buffering H02J7/14 takes precedence
• CPC Class Codes: H02J 7/35 with light sensitive cells

Abstract

A charging circuit for field devices is disclosed. The circuit has at least three modes and automatically shifts between the modes depending on voltage of the generator. In a first mode, the charging circuit provides voltage regulation. In a second mode, the charging circuit couples the generator directly to en energy storage device. In a third mode, the charging circuit decouples the generator from the storage device. A field device utilizing the charging circuit is also disclosed.

Claims

1. A charging system for a field device, the charging system comprising:

an electrical generator disposed to generate electricity from a source of potential energy;

a charging circuit coupled to the generator and disposed to measure a voltage output of the generator;

an electrical storage device coupled to the charging circuit; and

wherein the charging circuit includes an output to provide power to the field device, and wherein the charging circuit is configured to operate a plurality of modes based upon the voltage output of the generator.

2. The charging system of claim 1, wherein the charging circuit has a linear mode wherein the charging circuit provides a regulated output to the storage device.

3. The charging system of claim 2, wherein the charging circuit is in linear mode when the voltage output of the generator is above a bypass threshold.

4. The charging system of claim 1, wherein the charging circuit has a bypass mode wherein the generator is coupled directly to the storage device.

5. The charging system of claim 4, wherein the charging circuit consumes no more than 200 milliwatts in the bypass mode.

6. The charging system of claim 4, wherein the charging circuit is in bypass mode when the voltage output of the generator is below the bypass threshold and above a cutout threshold.

7. The charging system of claim 1, wherein the charging circuit has a cutout mode wherein the charging circuit decouples the storage device from the generator.

8. The charging system of claim 1, wherein the charging circuit is in cutout mode when the voltage output of the generator is below a cutout threshold.

9. The charging system of claim 1, wherein the generator includes a photovoltaic cell.

10. The charging system of claim 1, wherein the generator includes at least one of a wind-based generator module, a thermal generator module, a compressed-gas based generator, and a vibration-based generator.

11. The charging system of claim 1, wherein the electrical storage device is a rechargeable battery.

12. The charging system of claim 11, wherein the rechargeable battery is a gel cell lead acid battery.

13. The charging system of claim 12, and further comprising a temperature sensor operably coupled to the gel cell lead acid battery and to the charging circuit, and wherein the charging circuit limits charging current based upon a temperature of the gel cell lead acid battery.

14. The charging system of claim 1, and further comprising battery protection circuitry.

15. A field device comprising:

a transducer operably coupleable to a process;

a controller coupled to the transducer;

a communications module coupled to the controller and configured to provide process communications functions;

an energy conversion module configured to provide electrical energy to the field device, the energy conversion module including;

an electrical generator disposed to generate electricity from a source of potential energy;

a charging circuit coupled to the generator and disposed to measure a voltage output of the generator;

an electrical storage device coupled to the charging circuit; and

wherein the charging circuit includes an output to provide power to the field device, and wherein the charging circuit is configured to operate a plurality of modes based upon the voltage output of the generator.

16. The field device of claim 15, wherein the communications module is a wireless communications module.

17. The field device of claim 15, wherein the generator includes a photovoltaic cell.

18. The field device of claim 15, wherein the charging circuit has at least three operating modes.

19. The field device of claim 15, wherein the electrical storage device is a gel cell lead acid battery.

20. The field of claim 19, and further comprising a temperature sensor operably coupled to the gel cell lead acid battery and to the charging circuit, and wherein the charging circuit limits charging current based upon a temperature of the gel cell lead acid battery.