Efficient Power Conversion for Ultra Low Voltage Micro Scale Energy Transducers

• US 20110260536A1
• Filed: 03/10/2011
• Published: 10/27/2011
• Est. Priority Date: 03/10/2010
• Status: Active Grant

• Current Assignee: Purdue Research Foundation (Purdue University)
• Original Assignee: Purdue Research Foundation (Purdue University)
• Inventors: Lu, Chao, Park, Sang Phill, Raghunathan, Vijay, Roy, Kaushik
• Granted Patent: US 8,743,574 B2
• Time in Patent Office: Days
• US Class Current: 307/46
• CPC Class Codes: H01L 31/02021 for solar cells electrical connection means, e.g. junction boxes, specially adapted for structural association with photovoltaic modules H02S40/34
• CPC Class Codes: H02J 3/32 using batteries with converting means
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• CPC Class Codes: H02J 7/35 with light sensitive cells
• CPC Class Codes: H02M 3/073 Charge pumps of the Schenkel-type
• CPC Class Codes: H02M 3/077 with parallel connected charge pump stages
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

Abstract

A power converter is provided for an energy harvesting system of a micro-scale electronic device. The power converter is configured to transfer electrical energy from an energy transducer to an energy storage device. The power converter illustratively includes a tree topology charge pump.

Claims

1. An energy harvesting system for a micro-scale electronic device, the system comprising:

an energy transducer configured to produce electrical energy, the energy transducer having an output configured to supply a first voltage;

an energy storage device configured to store electrical energy; and

a power converter configured to transfer electrical energy from the transducer to the energy storage device, the power converter including a charge pump coupled between the energy transducer and the energy storage device and a control unit configured to control operation of the charge pump, the charge pump including a first stage, a second stage, and a third stage, each of the first and second stages having an output and at least one input coupled to the output of the transducer so that the transducer supplies the first voltage to the at least one input of the first and second stages, the first and second stages of the charge pump providing second and third voltages at their outputs, respectively, the second and third voltages being greater than the first voltage, the outputs of the first and second stages being coupled to first and second inputs of the third stage of the charge pump and an output of the third stage supplying a fourth voltage to the energy storage device, the fourth voltage being greater than the second and third voltages.

2. The system of claim 1, wherein the first and second stages of the charge pump each include a first input and a second input, the first and second inputs of the first and second stages being coupled to the output of the transducer so that the first voltage is provided to both the first and second inputs of the first and second stages of the charge pump.

3. The system of claim 2, wherein the first, second, and third stages of the charge pump each include a plurality of switches, the control unit being configured to provide at least one clocking signal to the first, second, and third stages of the charge pump to selectively open and close the plurality of switches.

4. The system of claim 3, wherein the first, second, and third stages of the charge pump each include at least one capacitor coupled between the plurality of switches, each capacitor being configured to store an electrical charge.

5. The system of claim 3, wherein the first, second, and third stages of the charge pump include first, second and third capacitors, respectively, coupled between the plurality of switches, the first, second and third capacitors each being configured to store an electrical charge.

6. The system of claim 5, wherein the first, second, and third capacitors each include a first plate and a second plate opposite the first plate, the first input of each stage of the charge pump being coupled to the first plate of the capacitor through a switch and the second input of each stage of the charge pump being coupled to the second plate of the capacitor through another switch.

7. The system of claim 1, wherein the second and third voltages are each about twice the first voltage.

8. The system of claim 1, wherein the fourth voltage is about four times the first voltage.

9. The system of claim 1, wherein the energy transducer includes at least one of a photovoltaic cell, a thermoelectric generator, and a fuel cell.

10. The system of claim 1, wherein the energy storage device includes at least one of an energy buffer, a rechargeable battery, and at least one capacitor.

11. The system of claim 1, wherein the first stage of the charge pump includes first and second inputs coupled to the output of the transducer, the first input of the first stage also being coupled to a first plate of a first capacitor through a first switch, and the second input of the first stage being coupled to a second, opposite plate of the first capacitor through a second switch, the first plate of the first capacitor also being coupled to a third switch which is also coupled to the output of the first stage;

the second stage of the charge pump includes first and second inputs coupled to the output of the transducer, the first input of the second stage also being coupled to a first plate of a second capacitor through a fourth switch, and the second input of the second stage being coupled to a second, opposite plate of the second capacitor through a fifth switch, the first plate of the second capacitor also being coupled to a sixth switch which is also coupled to the output of the second stage; and

wherein

the first input of the third stage is coupled to a first plate of a third capacitor, and the second input of the third stage is coupled to a second, opposite plate of the third capacitor, the first plate of the third capacitor also being coupled to a seventh switch which is also coupled to the output of the third stage, the control unit providing at least one clocking signal to selectively open and close the first, second third, fourth, fifth, and sixth switches to control operation of the charge pump.

12. The system of claim 11, wherein the control unit generates first and second non-overlapping clocking signals, the first clocking signal being supplied to the first, fifth, and sixth switches, and the second clocking signal being supplied to the second, third, fourth, and seventh switches to control operation of the charge pump.

13. The system of claim 11, wherein the second plate of the first capacitor is coupled through an eighth switch to ground, the second plate of the second capacitor is coupled through a ninth switch to ground, and the second plate of the third capacitor is coupled through a tenth switch to ground.

14. The system of claim 13, wherein the control unit generates first and second non-overlapping clocking signals, the first clocking signal being supplied to the first, fifth, sixth, and eighth switches, and the second clocking signal being supplied to the second, third, fourth, seventh, ninth, and tenth switches to control operation of the charge pump.

15. A power converter for an energy harvesting system of a micro-scale electronic device, the power converter being configured to transfer electrical energy from an energy transducer to an energy storage device, the power converter comprising:

a control unit configured to provide at least one clocking signal; and

a charge pump coupled to the control unit, the charge pump including a first stage, a second stage, and a third stage;

the first stage of the charge pump including first and second inputs, the first input of the first stage being coupled to a first plate of a first capacitor through a first switch, and the second input of the first stage being coupled to a second, opposite plate of the first capacitor through a second switch, the first plate of the first capacitor also being coupled to a third switch which is also coupled to an output of the first stage;

the second stage of the charge pump including first and second inputs, the first input of the second stage being coupled to a first plate of a second capacitor through a fourth switch, and the second input of the second stage being coupled to a second, opposite plate of the second capacitor through a fifth switch, the first plate of the second capacitor also being coupled to a sixth switch which is also coupled to an output of the second stage;

the third stage of the charge pump including first and second inputs, the first input of the third stage being coupled to a first plate of a third capacitor, and the second input of the third stage being coupled to a second, opposite plate of the third capacitor, the first plate of the third capacitor also being coupled to a seventh switch which is also coupled to an output of the third stage; and

wherein

an output from the energy transducer is coupled to the first and second inputs of the first and second stages of the charge pump and the outputs of the first and second stages are coupled to the first and second inputs, respectively, of the third stage of the charge pump, an output of the third stage being coupled to the energy storage device, and wherein the at least one clocking signal from the control unit is coupled to the first, second third, fourth, fifth, and sixth switches to control operation of the charge pump so that voltages at the outputs of the first and second stages are greater than the voltage supplied by the energy transducer and a voltage at the output of the third stage is greater than the voltages at the outputs of the first and second stages.

16. The system of claim 15, wherein the control unit generates first and second non-overlapping clocking signals, the first clocking signal being supplied to the first, fifth, and sixth switches, and the second clocking signal being supplied to the second, third, fourth, and seventh switches to control operation of the charge pump.

17. The system of claim 15, wherein the second plate of the first capacitor is coupled through an eighth switch to ground, the second plate of the second capacitor is coupled through a ninth switch to ground, and the second plate of the third capacitor is coupled through a tenth switch to ground.

18. The system of claim 17, wherein the control unit generates first and second non-overlapping clocking signals, the first clocking signal being supplied to the first, fifth, sixth, and eighth switches, and the second clocking signal being supplied to the second, third, fourth, seventh, ninth, and tenth switches to control operation of the charge pump.

19. A method for supplying power from an energy transducer to an energy storage device, the method comprising:

providing a charge pump including a first stage, a second stage, and a third stage;

supplying a voltage source from the energy transducer to at least one input of the first and second stages of the charge pump;

increasing the voltage received from the voltage source in the first and second stages of the charge pump in parallel;

supplying output voltages from the first and second stages to first and second inputs of the third stage of the charge pump;

increasing the voltage in the third stage compared to the output voltages of the first and second stages; and

supplying the increased voltage from the third stage to the energy storage device.

20. The method of claim 19, wherein the output voltages from the first and second stages of the charge pump are about twice the voltage of the voltage source, and wherein the output voltage from the third stage of the charge pump is about four times the voltage of the voltage source.