Energy Harvester

• US 20170257023A1
• Filed: 03/03/2016
• Published: 09/07/2017
• Est. Priority Date: 03/03/2016
• Status: Active Grant

• Current Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Original Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Inventors: Wu, Xiao, Blaauw, David Theodore, Sylvester, Dennis Michael Chen
• Granted Patent: US 10,476,382 B2
• Time in Patent Office: Days
• CPC Class Codes: H02J 50/001 Energy harvesting or scavenging
• 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 7/342 The other DC source being a battery actively interacting with the first one, i.e. battery to battery charging with circuits for polarity protection H02J7/0034
• CPC Class Codes: H02J 7/35 with light sensitive cells
• CPC Class Codes: H02M 1/0048 Circuits or arrangements for reducing losses using snubbers H02M1/34
• CPC Class Codes: H02M 1/36 Means for starting or stopping converters
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

Various implementations described herein are directed to a device having a charge pump and a capacitor. The charge pump may be configured for coupling between first and second power sources. The capacitor may be configured for coupling between the first power source and an input of the charge pump. In an energy harvest mode, the charge pump may decouple from the first and second power sources, and the first power source may charge the capacitor with a first voltage while the charge pump is decoupled from the first and second power sources. In an energy transfer mode, the charge pump may couple to the capacitor and the second power source to transfer the first voltage from the capacitor to the second power source during discharge of the first voltage from the capacitor.

Claims

1. A circuit, comprising:

a charge pump for coupling between first and second power sources; and

a buffering capacitor for coupling between the first power source and an input of the charge pump,

wherein in an energy harvest mode, the charge pump decouples from the first and second power sources, and the first power source charges the buffering capacitor with a first voltage while the charge pump is decoupled from the first and second power sources, and

wherein in an energy transfer mode, the charge pump couples to the buffering capacitor and the second power source to transfer the first voltage from the buffering capacitor to the second power source during discharge of the first voltage from the buffering capacitor.

2. The circuit of claim 1, wherein the charge pump receives the first voltage from the first power source and transfers at least a portion of the first voltage to the second power source for charging the second power source with the first voltage.

3. The circuit of claim 1, wherein the first power source comprises a solar power source, and wherein the second power source comprises a battery power source.

4. The circuit of claim 1, wherein the first power source charges the buffering capacitor from a first voltage state to a second voltage state with the first voltage, and wherein the second voltage state is at least greater than the first voltage state.

5. The circuit of claim 1, wherein the first voltage is discontinually transferred from the first power source to the second power source via the buffering capacitor and the charge pump.

6. The circuit of claim 1, wherein switching between the energy harvest mode and the energy transfer mode discontinuously transfers the first voltage from the first power source to the second power source via the buffering capacitor and the charge pump.

7. The circuit of claim 1, further comprising a first switch coupled between the buffering capacitor and the input of the charge pump for selectively decoupling the charge pump from the buffering capacitor during the energy harvest mode to reduce leakage.

8. The circuit of claim 7, wherein the first switch is further coupled between the first power source and the input of the charge pump for selectively decoupling the charge pump from the first power source during the energy harvest mode to reduce leakage.

9. The circuit of claim 1, further comprising a second switch coupled between an output of the charge pump and the second power source for selectively decoupling the second power source from the charge pump during the energy harvest mode to reduce leakage.

10. The circuit of claim 1, wherein in the energy transfer mode, the charge pump is further coupled to the first power source to transfer the first voltage from the first power source to the second power source.

11. The circuit of claim 1, further comprising a mode controller configured for sensing the first voltage at the first power source and the buffering capacitor, wherein the mode controller switches between the energy harvest mode and the energy transfer mode to discontinuously transfer the first voltage from the first power source to the second power source via the buffering capacitor and the charge pump.

12. The circuit of claim 11, wherein the charge pump comprises a switched capacitor network adapted for transferring the first voltage from the buffering capacitor to the second power source during discharge of the buffering capacitor.

13. The circuit of claim 12, further comprising a switched capacitor controller configured for receiving control signals from the mode controller to control the switched capacitor network of the charge pump based on the received control signals.

14. The circuit of claim 13, further comprising a third switch coupled between the second power source and the switched capacitor controller for decoupling the switched capacitor controller from the second power source during the energy harvest mode to reduce leakage.

15. A device, comprising:

a charge pump configured to receive voltage from a solar cell and transfer at least a portion of the voltage to a battery; and

a capacitor coupled between the solar cell and the charge pump,

wherein in an energy harvest mode, the solar cell charges the capacitor with the voltage when the charge pump is decoupled from the solar cell and the battery, and

wherein in an energy transfer mode, the charge pump is coupled to the capacitor and the battery to transfer the voltage from the capacitor to the battery during discharge of the capacitor.

16. The device of claim 15, wherein the voltage is discontinually transferred from the solar cell to the battery via the capacitor and the charge pump.

17. The device of claim 15, wherein switching between the energy harvest mode and the energy transfer mode discontinuously transfers the voltage from the solar cell to the battery via the capacitor and the charge pump.

18. A method, comprising:

in an energy harvest mode, decoupling a charge pump from first and second power sources, and charging a buffering capacitor with voltage from the first power source while the charge pump is decoupled from the first and second power sources, and

in an energy transfer mode, coupling the charge pump to the buffering capacitor and the second power source to transfer the voltage from the buffering capacitor to the second power source during discharge of the buffering capacitor.

19. The method of claim 18, further comprising:

in the energy transfer mode, coupling the charge pump to the first power source to transfer the voltage from the first power source to the second power source.

20. The method of claim 18, further comprising:

coupling the charge pump between the first and second power sources; and

coupling the buffering capacitor between the first power source and an input of the charge pump,

wherein the charge pump is configured to receive the voltage from the first power source and the capacitor and transfer at least a portion of the voltage to the second power source during discharge of the buffering capacitor.