SYSTEM AND METHOD FOR EFFICIENTLY HARVESTING ENVIRONMENTAL ENERGY

• US 20120274144A1
• Filed: 04/26/2012
• Published: 11/01/2012
• Est. Priority Date: 04/29/2011
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Gasparini, Alessandro, Ramorini, Stefano, Membretti, Giorgio Massimiliano
• Granted Patent: US 9,385,626 B2
• Time in Patent Office: Days
• US Class Current: 307/80
• CPC Class Codes: B60C 23/041 Means for supplying power to the signal- transmitting means on the wheel
• CPC Class Codes: B60C 23/0411 Piezoelectric generators
• CPC Class Codes: H02M 7/2176 comprising a passive stage to generate a rectified sinusoidal voltage and a controlled switching element in series between such stage and the output

Abstract

A transducer converts energy coming from an energy source into an electrical signal for storage as electrical energy on a first storage element. A switch is selectively actuated to pass electrical energy from the first storage element to a second storage element. The selective actuation of the switch is driven by sensing electrical energy stored in the second storage element. The switch is closed when electrical energy in the second storage element is sensed to fall below a first threshold. The switch is opened when electrical energy in the second storage element is sensed to rise above a second threshold.

Claims

1. A system, comprising:

a transducer configured to convert energy coming from an external energy source into an electrical signal;

a first storage element coupled to an output of the transducer and configured to receive said electrical signal and store electrical energy,

a second storage element configured to store electrical energy; and

a switch coupled between the first and the second electrical-energy storage elements and operable to electrically couple the first and second storage elements to one another and, alternatively, uncouple the first and second storage elements from one another.

2. The system according to claim 1, wherein the first storage element comprises a first conduction terminal and a second conduction terminal, wherein the second storage element comprises a first conduction terminal and a second conduction terminal, wherein the second conduction terminals of the first and second storage elements are connected to a common reference terminal, wherein the first conduction terminals of the first and second storage elements are connected to respective terminals of the switch in such a way that, when the switch is operated to electrically couple the first and second storage elements, the respective first conduction terminals of the first and second storage elements are coupled to one another.

3. The system according to claim 1, wherein said first storage element has an electrical energy storage capacity greater than that of said second storage element.

4. The system according to claim 1, further comprising control logic having an output coupled to control said switch, said control logic configured to close the switch when the electrical energy stored in the second storage element is lower than a first threshold value, and further configured to open the switch when the electrical energy stored in the second storage element is higher than a second threshold value.

5. The system according to claim 4, wherein the control logic comprises:

a comparator with hysteresis configured to receive on a first input a first comparison signal indicative of electrical energy stored in the second storage element, and receive on a second input a second predefined comparison signal, and supply at the output a third comparison signal indicative of a result of a comparison between the first and second comparison signals;

a control and driving circuit configured to receive the third comparison signal and, on the basis of the third comparison signal, control opening or closing of the switch.

6. The system according to claim 1, wherein the first storage element includes a capacitor and wherein the electrical signal generated by the transducer is an AC voltage signal, the system further comprising a scavenging interface having an input connected to the transducer and an output connected to the first storage element, the scavenging interface configured to receive at an input the electrical signal and generate at an output a first intermediate DC signal to charge the first storage element.

7. The system according to claim 1, further comprising a DC-DC converter coupled between the second storage element and an electrical load, said DC-DC converter configured to receive a second intermediate signal depending upon the electrical energy stored in the second storage element and supply said electrical load via said second intermediate signal.

8. The system according to claim 7, wherein the second storage element includes a capacitor having biasing terminals, the DC-DC converter further configured to accept a voltage signal having a value lower than a maximum value, and the second storage element being configured in such a way that the difference of potential that, in use, is set up across its terminals has a value lower than said maximum value.

9. The system according to claim 1, comprising an energy-harvesting system for use in harvesting energy from movement of a support.

10. The system according to claim 9, wherein said support is a means of transport.

11. The system according to claim 9, wherein said transducer is chosen in the group comprising:

electrochemical transducer, electromechanical transducer, electroacoustic transducer, electromagnetic transducer, photoelectric transducer, electrostatic transducer, thermoelectrical transducer.

12. An energy-harvesting method, comprising:

converting, by a transducer, energy from an external energy source into electrical energy to generate an electrical signal;

storing said electrical energy in a first storage element;

coupling the first storage element to a second storage element so as to store, in the second storage element, at least a portion of the electrical energy stored in the first storage element;

alternatively, uncoupling the first storage element from the second storage element so as to insulate the first storage element from the second storage element; and

during uncoupling, supplying an electrical load with electrical energy stored in the second storage element.

13. The method according to claim 12, further comprising monitoring the electrical energy stored in the second storage element, wherein a coupling of the first storage element to the second storage element is carried out when the electrical energy stored in the second storage element falls lower than a first threshold value, and wherein uncoupling of the first storage element from the second storage element is carried out when the electrical energy stored in the second storage element rises higher than a second threshold value.

14. The method according to claim 12, wherein monitoring:

supplying, on a first input of a comparator with hysteresis, a first comparison signal indicative of the electrical energy stored in the second storage element;

supplying, on a second input of the comparator with hysteresis, a second predefined comparison signal; and

generating, at an output of the comparator with hysteresis, a third comparison signal indicative of a result of a comparison between the first and second comparison signals,

wherein said coupling and uncoupling actions are performed on the basis of a value assumed by the third comparison signal.

15. The method according to claim 12, wherein the first storage element includes a capacitor and wherein the electrical signal generated by the transducer is an AC voltage signal, the method further comprising:

rectifying the electrical signal generated by the transducer to generate a first intermediate DC signal; and

charging the first storage element with the first intermediate signal.

16. A circuit, comprising:

a first capacitor having a first terminal coupled to a reference voltage node and a second terminal coupled to an input node and configured to store first electrical energy;

a second capacitor having a third terminal coupled to said reference voltage node and a fourth terminal and configured to store second electrical energy;

a switching circuit having an input terminal coupled to the first terminal and an output terminal coupled to the fourth terminal;

a hysteresis comparator coupled to sense the second electrical energy at the fourth terminal and configured to close the switching circuit in response to sensed second electrical energy falling below a first threshold and open the switching circuit in response to sensed electrical energy rising above a second threshold.

17. The circuit of claim 16, further comprising a rectifying circuit configured to rectify an AC signal to generate an DC signal at said input node.

18. The circuit of claim 17, further comprising a transducer circuit configured to convert non-electrical energy into said AC signal.

19. The circuit of claim 18, further comprising a DC-DC converter circuit having an input coupled to said fourth terminal and configured to supply power to a load from the second electrical energy.

20. The circuit of claim 16, wherein said first capacitor has an electrical energy storage capacity greater than that of said second capacitor.