Maximum power point tracking in energy harvesting DC-to-DC converter

• US 10,063,081 B2
• Filed: 01/07/2016
• Issued: 08/28/2018
• Est. Priority Date: 01/07/2015
• Status: Active Grant

• Current Assignee: Dialog Semiconductor B.V. (Renesas Electronics Corporation)
• Original Assignee: Dialog Semiconductor B.V. (Renesas Electronics Corporation)
• Inventors: Kruiskamp, Marinus Wilhelmus
• Primary Examiner(s): Houston, Adam
• Application Number:
  US14/989,926
• Publication Number:
  US 20160197508A1
• Time in Patent Office: 964 Days
• Field of Search: 307130
• 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: H02M 3/04 by static converters
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators

Abstract

An energy harvesting direct current to direct current ‘DC-to-DC’ converter circuit is presented. It is comprised of an energy storage element, an input configured to receive an input voltage, an output; switching means configured to perform cycles. Each cycle is marked when the input voltage reaches a reference voltage, switching the circuit such that the energy storage element enters into an energy charging state in which the energy storage element stores energy provided by the input voltage. Control means is configured to determine the reference voltage based on the number of cycles per time period performed by the circuit.

Claims

1. An energy harvesting direct current to direct current ‘

DC-to-DC’

converter circuit comprising

an energy storage element;

an input configured to receive an input voltage;

an output;

switching means configured to perform cycles wherein each cycle comprises, when the input voltage reaches a reference voltage, switching the circuit such that the energy storage element enters into an energy charging state in which the energy storage element stores energy provided by the input voltage;

and control means configured to determine the reference voltage based on a number of cycles per time period performed by the circuit, wherein the energy harvesting ‘

DC-to-DC’

converter circuit operate is configured to operate in a discontinuous conduction mode ‘

DCM’

.

2. The energy harvesting DC-to-DC converter circuit of claim 1 wherein the cycle further comprises, when an energy stored in the energy storage element reaches an upper energy threshold, switching the circuit such that the energy storage element enters into an energy discharging state in which the energy storage element provides energy to the output.

3. The energy harvesting DC-to-DC converter circuit of claim 1 wherein the cycle further comprises, when the energy stored in the energy storage element reaches a lower energy threshold, switching the circuit such that the energy storage element enters into a waiting state in which the energy storage element is not charging neither discharging energy.

4. The energy harvesting ‘

DC-to-DC’

converter circuit of claim 1, wherein the control means is configured to vary the reference voltage in order to obtain a maximum number of cycles per time period performed by the circuit.

5. The energy harvesting ‘

DC-to-DC’

converter circuit of claim 1, wherein the energy storage element comprises an inductor.

6. The energy harvesting ‘

DC-to-DC’

converter circuit of claim 2, wherein the energy storage element comprises a first end connected to the input and a second end, and wherein the switching means comprise a first switch comprising a first end connected to the second end of the energy storage element and a second end connected to ground and wherein the first switch is configured to connect the energy storage element to the ground when the input voltage reaches the reference voltage such that the energy storage element enters into a charging state and to disconnect the energy storage element from the ground when the energy stored in the energy storage element reaches the upper energy threshold.

7. The energy harvesting ‘

DC-to-DC’

converter circuit of claim 6, wherein the switching means further comprises a second switch having a first end connected to the second end of the energy storage element and having a first end connected to the output and wherein the second switch is configured to connect the energy storage element to the output when the energy stored in the energy storage element reaches the upper energy threshold such that the energy storage element enters into a discharging state.

8. The energy harvesting ‘

DC-to-DC’

converter circuit of claim 2, wherein the energy storage element comprises a first end and a second end wherein the second end is connected to the output, and wherein the switching means comprise a third switch having a first end connected to the first end of the energy storage element and having a second end connected to the input and wherein the third switch is configured to connect the energy storage element to the input when the input voltage reaches the reference voltage such that the energy storage element enters into the charging state and to disconnect the energy storage element from the input when the energy stored in the energy storage element reaches the upper energy threshold.

9. The energy harvesting ‘

DC-to-DC’

converter circuit of claim 8, wherein the switching means further comprises a fourth switch having a first end connected to the first end of the energy storage element and having a second end connected to the ground and wherein the fourth switch is configured to connect the energy storage element such that the energy storage element enters into a discharging state when the energy stored in the energy storage element reaches the upper energy threshold.

10. The energy harvesting ‘

DC-to-DC’

converter circuit of claim 1, wherein the control means further comprises a first comparator configured to compare the input voltage to the reference voltage.

11. The energy harvesting ‘

DC-to-DC’

converter circuit of claim 2, wherein the control means further comprises a second comparator configured to compare the energy stored in the energy storage element to the upper energy threshold.

12. The energy harvesting ‘

DC-to-DC’

converter circuit of claim 3, wherein the control means comprises a third comparator configured to compare the energy stored in the energy storage element to the lower energy threshold.

13. A method of operating an energy harvesting direct current to direct current ‘

DC-to-DC’

converter circuit, the method comprising the steps of;

operating the circuit in order to perform cycles wherein each cycle comprises;

when the input voltage reaches a reference voltage, switching the circuit such that the energy storage element enters into an energy charging state in which the energy storage element stores energy provided by the input voltage;

determining the reference voltage based on a number of cycles per time period performed by the circuit, wherein the energy harvesting ‘

DC-to-DC’

converter circuit operates in a discontinuous conduction mode ‘

DCM’

.

14. The method of claim 13, wherein the cycle further comprises, when an energy stored in the energy storage element reaches an upper energy threshold, switching the circuit such that the energy storage element enters into an energy discharging state in which the energy storage element provides energy to the output.

15. The method of claim 14, wherein the cycle further comprises, when the energy stored in the energy storage element reaches a lower energy threshold, switching the circuit such that the energy storage element enters into a waiting state in which the energy storage element is not charging neither discharging energy.

16. The method of claim 13, wherein the control means varies the reference voltage in order to obtain a maximum number of cycles per time period performed by the circuit.

17. The method of claim 13, wherein the energy storage element comprises an inductor.

18. The method of claim 14, wherein the energy storage element comprises a first end connected to the input and a second end, and wherein the switching means comprise a first switch comprising a first end connected to the second end of the energy storage element and a second end connected to ground and wherein the first switch connects the energy storage element to the ground when the input voltage reaches the reference voltage such that the energy storage element enters into a charging state and to disconnect the energy storage element from the ground when the energy stored in the energy storage element reaches the upper energy threshold.

19. The method of claim 18, wherein the switching means further comprises a second switch having a first end connected to the second end of the energy storage element and having a first end connected to the output and wherein the second switch connects the energy storage element to the output when the energy stored in the energy storage element reaches the upper energy threshold such that the energy storage element enters into a discharging state.

20. The method of claim 14, wherein the energy storage element comprises a first end and a second end wherein the second end is connected to the output, and wherein the switching means comprise a third switch having a first end connected to the first end of the energy storage element and having a second end connected to the input and wherein the third switch connects the energy storage element to the input when the input voltage reaches the reference voltage such that the energy storage element enters into the charging state and to disconnect the energy storage element from the input when the energy stored in the energy storage element reaches the upper energy threshold.

21. The method of claim 20, wherein the switching means further comprises a fourth switch having a first end connected to the first end of the energy storage element and having a second end connected to the ground and wherein the fourth switch connects the energy storage element such that the energy storage element enters into a discharging state when the energy stored in the energy storage element reaches the upper energy threshold.

22. The method of claim 13, wherein the control means further comprises a first comparator to compare the input voltage to the reference voltage.

23. The method of claim 14, wherein the control means further comprises a second comparator to compare the energy stored in the energy storage element to the upper energy threshold.

24. The method of claim 15, wherein the control means comprises a third comparator to compare the energy stored in the energy storage element to the lower energy threshold.