Apparatus and method for charging an energy storage source

• US 6,194,793 B1
• Filed: 08/07/1998
• Issued: 02/27/2001
• Est. Priority Date: 08/07/1998
• Status: Expired due to Term

• Current Assignee: OKC Products, Inc.
• Original Assignee: OKC Products, Inc.
• Inventors: Fisher, Carl Jr.
• Primary Examiner(s): Ballato, Josie
• Assistant Examiner(s): DeBeradinis, Robert L.
• Application Number:
  US09/131,254
• Time in Patent Office: 935 Days
• Field of Search: 307/43, 307/46, 307/66
• US Class Current: 307/66
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence
• CPC Class Codes: H02J 7/35 with light sensitive cells

Abstract

A power supply for supplying energy to a load includes an energy supply source for generating energy, an energy storage device that is charged from the energy generated by the energy supply source, an optional regulator for improving the energy matching of the energy supply source and the energy storage device, an energy converter for delivering energy from the energy storage device and/or the energy supply source to a load, a detector for monitoring the energy level of the energy storage device and for determining when to activate the energy converter to allow energy delivery to the load from the energy storage device and/or the energy supply source, an optional energy discharge controller that allows the energy storage device to discharge over time, and an optional switch controller for controlling a switch, valve, relay, etc.

Claims

1. Power supply apparatus, comprising:

an energy storage device coupled to a first node and being capable of storing energy;

an energy supply source coupled to said first node and being capable of producing energy;

an energy converter having an input terminal coupled to said first node and an output terminal that is connectable to a load, said energy converter being capable of converting electric energy of varying voltages at said input terminal to electric energy at a constant voltage and of delivering the electric energy at said constant voltage to a load connected to said output terminal, but where said energy converter converts energy from said input terminal to said output terminal at efficiency levels which vary as a function of voltage on said input terminal such that a minimum desired energy conversion efficiency requires a corresponding minimum threshold voltage on said first node at said input terminal, and wherein said energy converter is actuateable in response to a control signal to convert electric energy from said input terminal to electric energy at said constant voltage for said load; and

a detector connected to said first node and being capable of sensing voltage of said energy storage device at said first node and of providing said control signal upon sensing voltage at said first node which is at or above said minimum threshold voltage.

2. The apparatus of claim 1, including a discharger coupled to said first node.

3. The apparatus of claim 2, wherein said discharger includes a resistive component.

4. The apparatus of claim 1, including a discharger coupled to said energy storage device and capable of draining said energy stored in said energy storage device.

5. The apparatus of claim 1, including a switch controller coupled to said energy storage device and to said load.

6. The apparatus of claim 5, wherein said switch controller receives energy from said energy storage device.

7. The apparatus of claim 5, wherein said switch controller receives energy from said energy supply device.

8. The apparatus of claim 5, wherein said load receives energy from said energy converter.

9. The apparatus of claim 8, wherein said load generates a load signal and transmits said load signal to said switch controller.

10. The apparatus of claim 9, wherein said switch controller generates a controller signal responsive to said load signal.

11. The apparatus of claim 1, wherein said energy storage source includes at least one battery.

12. The apparatus of claim 1, wherein said energy source includes at least one capacitor.

13. The apparatus of claim 1, wherein said energy supply source includes at least one solar cell.

14. The apparatus of claim 1, including a voltage regulator interposed between said energy supply source and said first node, said voltage regulator being capable of capping voltage supplied at said first node to a maximum voltage limit, regardless of higher voltage levels provided by said energy supply source.

15. The apparatus of claim 14 wherein said maximum voltage limit is approximately equal to said energy storage device'"'"'s preferred maximum voltage.

16. The apparatus of claim 14, wherein said maximum voltage limit is set such that said energy converter operates at a predetermined conversion efficiency level.

17. The apparatus of claim 1, wherein said energy storage device comprises a rechargeable battery and said energy supply source comprises a solar cell electric generator.

18. The apparatus of claim 1, wherein said minimum desired energy conversion efficiency is about fifty percent (50%).

19. The apparatus of claim 1, wherein said minimum threshold voltage is about 2 volts.

20. The apparatus of claim 1, wherein said minimum desired energy conversion efficiency is about seventy percent (70%).

21. The apparatus of claim 1, wherein said minimum threshold voltage is about 2.5 volts.

22. The apparatus of claim 1, including a diode interposed between said first node and said energy supply source in a manner that prevents back flow of electric energy from said energy storage device to said energy supply source.

23. A solar power supply system, comprising:

a solar power source connected to a node, said solar power source having a capacity to produce electric energy at varying voltage and current output levels depending on available sunlight;

a rechargeable battery connected to said node, said rechargeable battery being capable of receiving and storing electric energy from said solar power source via said node at varying voltage levels and of delivering stored electric energy to said node at varying voltage levels;

an energy converter that has an input terminal connected to said node and an output terminal that is connectable to a load, said energy converter being actuatable in response to a control signal to convert electric energy of varying voltages from said node to electric energy of a constant voltage level at said outlet terminal for powering said load, and said energy converter having varying energy conversion efficiency levels that vary as a function of the varying voltage levels at said node, there being a minimum threshold voltage level at said node that corresponds with a minimum desired energy conversion efficiency level at which the solar power source can deliver energy to the load and supply energy to the rechargeable battery; and

a voltage detector connected to said node and having a capability of providing said control signal to said energy converter in response to detection of voltage at said node that is equal to or greater than said minimum threshold voltage level.

24. The solar power supply system of claim 23, wherein said minimum desired energy conversion efficiency level is about fifty percent (50%).

25. The solar power supply system of claim 23, wherein said minimum threshold voltage level is about 2.0 volts.

26. The solar power supply system of claim 23, wherein said minimum desired energy conversion efficiency level is about seventy percent (70%).

27. The solar power supply system of claim 23, wherein said minimum threshold voltage level is about 2.5 volts.

28. The solar power supply system of claim 23, wherein said rechargeable battery has a maximum desired voltage level, thus there is a maximum desired voltage level at said node, and solar power supply system includes a voltage regulator positioned between said solar power source and said node, said voltage regulator having a capability of capping electric energy produced by said solar power source to not exceed said maximum desired voltage level at said node.

29. The solar power supply system of claim 23, including a diode positioned between the node and the solar power source in a manner that prevents back flow of electric energy from the rechargeable battery to the solar power source.

30. The solar power supply system of claim 23, wherein the solar power source includes at least one solar cell.

31. The solar power supply system of claim 23, wherein said rechargeable battery comprises a capacitor.

32. The solar supply system of claim 23, wherein said rechargeable battery comprises a Ni˜

Cd battery.

33. A power supply system, comprising:

an energy recharge source connected to a node, said energy recharge source having a capacity to produce electric energy, but at varying energy output levels that can decrease to be insufficient to power a load and then increase again;

an energy storage device connected to said node, said energy storage device being capable of receiving and storing electric energy from said energy recharge source via said node at varying voltage levels and of delivering stored electric energy to said node at varying voltage levels;

an energy converter that has an input terminal connected to said node and an output terminal that is connectable to the load, said energy converter being actuatable in response to a control signal to convert electric energy of varying voltages from said node to electric energy of a constant voltage level at said outlet terminal for powering the load, and said energy converter having varying energy conversion efficiency levels that vary as a function of the varying voltage levels at said node, there being a minimum threshold voltage level at said node that corresponds with a minimum desired energy conversion efficiency level at which the energy recharge source can deliver energy to the load and supply energy to the energy storage device to recharge the energy storage device; and

a voltage detector connected to said node and having a capability of providing said control signal to said energy converter in response to detection of voltage at said node that is equal to or greater than said minimum threshold voltage level.

34. The power supply system of claim 33, wherein said energy recharge source comprises a solar cell, panel, or array, and said varying energy output levels vary as a function of sunlight intensity incident on said solar cell, panel, or array.

35. The apparatus of claim 34, wherein said energy storage device'"'"'s maximum energy output level is approximately equal to said energy storage device'"'"'s energy storage capacity.

36. A method of initially actuating a power supply that comprises a solar power source, a rechargeable energy storage device that initially has virtually no energy stored in it so that its voltage is virtually zero, and a DC—

DC voltage converter with its input connected at a common node to both the solar power source and the rechargeable energy storage device and with its output connected to a load, the method comprising;

exposing the solar power source to light energy to produce electric energy to said node while keeping said DC—

DC voltage converter deactuated so that all of the electric energy produced by the solar power source flows into said rechargeable energy storage device and none of the electric energy flows to the load in order to build up voltage of said rechargeable energy storage device at said common node;

monitoring voltage of said rechargeable energy storage device at said common node and, when the voltage of the rechargeable energy storage device at said common node rises to a minimum voltage threshold that corresponds to a minimum desired energy conversion efficiency capability of said DC—

DC voltage converter, then actuating said DC—

DC voltage converter to convert and deliver at least some of the electric energy available at said common node to said load with said DC—

DC voltage converter operating at or above said minimum desired energy conversion efficiency.

37. The method of claim 36, wherein said minimum desired energy conversion efficiency is about fifty percent (50%).

38. The method of claim 36, wherein said minimum desired energy conversion efficiency is about seventy percent (70%).

39. A method of powering a load with a solar power source that produces electric energy at varying voltage and current output levels depending on available sunlight, comprising:

connecting the solar power source to a node;

connecting a rechargeable battery to said node in such a manner that said rechargeable battery can receive electric energy from the node for storage and can deliver stored electric energy to the node;

connecting an energy converter to the node in a manner such that said energy converter is capable of converting electric energy of varying voltage levels from the node and at corresponding varying energy conversion efficiencies to a electric energy of constant voltage at a converter output;

connecting the load to the converter output;

determining a minimum energy conversion efficiency level and a corresponding minimum threshold voltage level at the node at which the solar power source can deliver electric energy to the load and supply electric energy to recharge the rechargeable battery;

monitoring the varying voltage levels at the node; and

enabling the energy converter to convert electric energy of the varying voltage levels at the node to electric energy of a constant voltage level at the converter output for the load only when the node is at a voltage equal to or greater than the minimum threshold voltage level.

40. The method of claim 39, including positioning a diode between the solar power source and the node in a manner that prevents back flow of electric energy from the rechargeable battery to the solar power source.

41. The method of claim 39, wherein the minimum energy conversion efficiency level is about fifty percent (50%).

42. The method of claim 39, wherein the minimum energy conversion efficiency level is about seventy percent (70%).