RECHARGE TUNING TECHNIQUES FOR AN IMPLANTABLE DEVICE

• US 20120262108A1
• Filed: 04/04/2012
• Published: 10/18/2012
• Est. Priority Date: 04/18/2011
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Olson, David P., Eisch, Jay T., Nolan, Joseph J., Delisi, Nicholas A., LaBrosse, Philip R.
• Granted Patent: US 9,623,257 B2
• Time in Patent Office: Days
• US Class Current: 320/108
• CPC Class Codes: A61N 1/3787 from an external energy source

Abstract

Techniques are disclosed for tuning a frequency at which an external device transcutaneously transfers energy. The transferred energy may be used to charge a rechargeable power source of an implantable medical device (IMD) and/or to power the IMD directly. One embodiment relates to a charging system that may comprise a circuit to drive a primary coil of an external device at a drive frequency and a control circuit to tune the drive frequency based on a characteristic of a monitored signal that is associated with the primary coil. The characteristic is not present when the primary coil is being driven at a resonant frequency of the system. In a specific example, the characteristic comprises a stub pulse and the control circuit is configured to tune the drive frequency based on at least one of a relative timing and a width of the stub pulse.

Claims

1. A charging system configured to transcutaneously deliver power, comprising:

a primary coil;

a drive circuit to drive the primary coil at a drive frequency; and

a control circuit to tune the drive frequency based on a characteristic of a signal that is associated with the primary coil, wherein the characteristic is not present when the primary coil is being driven at a resonant frequency of the system.

2. The charging system of claim 1, further comprising an edge detect circuit configured to detect the characteristic.

3. The charging system of claim 1, wherein the control circuit is configured to change the drive frequency based on relative timing between the characteristic and another characteristic of the signal.

4. The charging system of claim 1, wherein the characteristic comprises a stub pulse, and wherein the control circuit is configured to decrease the drive frequency if the stub pulse appears within a predetermined time period of another characteristic of the signal and otherwise the control circuit is configured to increase the frequency of the signal.

5. The charging system of claim 1, wherein the characteristic comprises a stub pulse, and wherein the control circuit is configured to change the drive frequency by an amount that is based on a width of the stub pulse.

6. The charging system of claim 1, wherein the drive circuit comprises an H-bridge circuit.

7. The charging system of claim 1, wherein the control circuit is configured to increase a duty cycle at which the primary coil is being driven until the characteristic first appears in the signal at a first frequency, to adjust the drive frequency until the characteristic disappears and reappears at a second frequency, and to adjust the drive frequency to be the average of the first and the second frequencies.

8. The charging system of claim 1, wherein the control circuit is configured to determine a high frequency at which the characteristic first appears in the signal and a low frequency at which the characteristic first appears in the signal, and to adjust the drive frequency to be the average of the high and the low frequencies.

9. The charging system of claim 1, wherein the control circuit is configured to monitor the characteristic of the signal to determine a location at which to position the primary coil to transcutaneously deliver power.

10. The charging system of claim 1, wherein the control circuit is configured to adjust the drive frequency until the characteristic disappears at a first frequency and reappears at a second frequency, and to adjust the drive frequency to be the average of the first and second frequencies.

11. The charging system of claim 1, wherein the drive circuit is configured to enforce a dead period during which the primary coil is not being driven and wherein the characteristic occurs during the dead period.

12. The charging system of claim 1, further comprising a detection circuit to detect the characteristic, the detection circuit being coupled to a circuit node associated with the primary coil that is not being driven at a time when the characteristic occurs.

13. The system of claim 1, further comprising:

a cable coupled to the primary coil; and

wherein the control circuit is carried by the cable.

14. The system of claim 1, further comprising:

an implantable medical device (IMD) configured to receive the transcutaneously-delivered power; and

a programmer configured to exchange at least one of data and programmed instructions with the IMD, and wherein the programmer comprises, or is communicatively coupled to, the control circuit.

15. A system, comprising:

a circuit configured to generate a signal associated with transcutaneously delivering power, and to tune the signal to a resonant frequency of the system based on a characteristic in the signal that is not present when the signal is at the resonant frequency of the system.

16. The system of claim 15, wherein the circuit is configured to adjust the frequency of the signal based on relative timing between the characteristic in the signal that is not present when the signal is at the resonant frequency of the system and a characteristic of the signal that is present when the signal is at the resonant frequency of the system.

17. The system of claim 16, wherein the characteristic of the signal that is present when the signal is at the resonant frequency is one of a negative-to-positive-going or a positive-to-negative-going transition.

18. The system of claim 15, wherein the characteristic in the signal that is not present when the signal is at the resonant frequency of the system comprises a stub pulse.

19. The system of claim 15, wherein the circuit is configured to automatically tune the signal based on a predetermined trigger event occurring while transcutaneously delivering power.

20. The system of claim 15, further comprising an implantable medical device to receive the transcutaneously delivered power.

21. A method of transcutaneously delivering power, comprising:

driving a primary coil;

monitoring a signal associated with the primary coil; and

adjusting a drive signal that is driving the primary coil to a resonant frequency based on a characteristic in the monitored signal that is not present when the drive signal is at the resonant frequency.

22. The method of claim 21, further comprising adjusting a location of the primary coil by monitoring at least one of a frequency at which the primary coil is being driven or a voltage at which the primary coil is being driven.

23. The method of claim 21, further comprising detecting the characteristic by detecting a transition in the monitored signal.

24. The method claim 21, wherein adjusting the drive signal comprises adjusting a frequency of the drive signal based on relative timing of the characteristic in the monitored signal that is not present when the drive signal is at the resonant frequency and a characteristic of the monitored signal that is present when the drive signal is at the resonant frequency.

25. The method of claim 21, wherein the characteristic comprises a pulse, and further comprising adjusting the frequency of the drive signal by an amount that is based on a width of the pulse.

26. The method of claim 21, further comprising:

adjusting the frequency of the drive signal until the characteristic appears at a high frequency;

adjusting the frequency of the drive signal until the characteristic appears at a low frequency; and

setting the frequency of the drive signal to the average of the high and low frequencies.

27. The method of claim 21, further comprising monitoring a signal to determine a physical location at which to position the primary coil while the primary coil is being driven.

28. The method of claim 27, wherein the signal monitored to determine the physical location is the monitored signal associated with the primary coil.

29. A system, comprising:

coil means for transcutaneously delivering power;

signal generation means for generating a signal in the coil means; and

control means for tuning a frequency of the signal based on a characteristic of the signal that is not present when the coil means is driven at a resonant frequency of the system.

30. The system of claim 29, further comprising implantable medical device means for receiving the transcutaneously delivered power.