Efficient external charger for an implantable medical device optimized for fast charging and constrained by an implant power dissipation limit

Patent metadata

Field	Value
Publication number	US-9358399-B2
Application number	US-201414292169-A
Country	US
Kind code	B2
Filing date	May 30, 2014
Priority date	Oct 8, 2009
Publication date	Jun 7, 2016
Grant date	Jun 7, 2016

Abstract

An external charger for a battery in an implantable medical device and charging techniques are disclosed. Simulation data is used to model the power dissipation of the charging circuitry in the implant at varying levels of implant power. A power dissipation limit constrains the charging circuitry from producing an inordinate amount of heat to the tissue surrounding the implant, and duty cycles of a charging field are determined so as not to exceed that limit. A maximum simulated average battery current determines the optimal (i.e., quickest) battery charging current, and at least an optimal value for a parameter indicative of that current is determined and stored in the external charger. During charging, the actual value for that parameter is determined, and the intensity and/or duty cycle of the charging field are adjusted to ensure that charging is as fast as possible, while still not exceeding the power dissipation limit.

First claim

What is claimed is:

1. A method for charging a battery in an implantable medical device, comprising:
generating a magnetic charging field using an external charger, the magnetic charging field for producing a battery charging current in the battery in the implantable medical device during a charging session;
determining a parameter indicative of a coupling between the external charger and the implantable medical device during the charging session; and
adjusting in accordance with the parameter: (1) an intensity of the magnetic charging field, and (2) a duty cycle of the magnetic charging field, during the charging session.

2. The method of claim 1 , wherein the parameter is indicative of the produced battery charging current during the charging session.

3. The method of claim 1 , wherein the parameter is indicative of heating in the implantable medical device during the charging session.

4. The method of claim 1 , wherein the parameter is received at the external charger via telemetry from the implantable medical device.

5. The method of claim 4 , wherein the parameter comprises a voltage across charging circuitry serially coupled to the battery in the implantable medical device, wherein the battery charging current passes through the charging circuitry.

6. The method of claim 4 , wherein the parameter is telemetered to the external charger during an off period of the duty cycle.

7. The method of claim 1 , wherein adjusting the intensity comprises comparing the parameter to an optimal value for the parameter in the external charger.

8. The method of claim 7 , wherein the optimal value for the parameter comprises a value at which an average of the battery charging current is maximized.

9. The method of claim 7 , wherein the intensity is adjusted to bring the parameter to the optimal value.

10. The method of claim 1 , wherein the external charger comprises a memory, wherein the memory comprises possible values for the parameter and a duty cycle associated with each possible value, wherein each duty cycle in the memory is determined in accordance with a power dissipation limit for the implantable medical device.

11. The method of claim 10 , wherein adjusting the duty cycle comprises determining an adjusted duty cycle using the parameter and the duty cycles in the memory.

12. The method of claim 10 , wherein the possible values for the parameter correspond to different battery charging currents, and wherein the duty cycle associated with each possible value is determined so as not to exceed a power dissipation limit in the implantable medical device.

13. The method of claim 1 , wherein the intensity and duty cycle are additionally adjusted in accordance with a voltage of the battery.

14. The method of claim 1 , wherein the parameter is periodically determined during the charging session, and wherein the intensity and duty cycle of the magnetic charging field are periodically adjusted in accordance with the periodically-determined parameter during the charging session.

15. A method for charging a battery in an implantable medical device, comprising:
generating a magnetic charging field using an external charger, the magnetic charging field for producing a battery charging current in the battery in the implantable medical device during a charging session;
determining a parameter indicative of a coupling between the external charger and the implantable medical device during the charging session; and
adjusting the magnetic charging field in accordance with the parameter,
wherein the implantable medical device comprises a power dissipation limit determined by the power draw of the implantable medical device in response to the magnetic charging field during the charging session, and
wherein the external charger adjusts the magnetic charging field so as not to exceed the power dissipation limit in the implantable medical device.

16. The method of claim 15 , wherein the parameter is indicative of the produced battery charging current during the charging session.

17. The method of claim 15 , wherein the parameter is received at the external charger via telemetry from the implantable medical device.

18. The method of claim 17 , wherein the parameter comprises a voltage across charging circuitry serially coupled to the battery in the implantable medical device, wherein the battery charging current passes through the charging circuitry.

19. The method of claim 17 , wherein the parameter is telemetered to the external charger during an off period of the duty cycle.

20. The method of claim 15 , wherein an intensity and duty cycle of the magnetic charging field are adjusted in accordance with the parameter.

21. The method of claim 20 , wherein adjusting the intensity comprises comparing the parameter to an optimal value for the parameter in the external charger.

22. The method of claim 21 , wherein the optimal value for the parameter comprises a value at which an average of the battery charging current is maximized.

23. The method of claim 21 , wherein the intensity is adjusted to bring the parameter to the optimal value.

24. The method of claim 15 , wherein the external charger comprises a memory, wherein the memory comprises possible values for the parameter and a duty cycle for the magnetic charging filed associated with each possible value, wherein each duty cycle in the memory is determined in accordance with the power dissipation limit for the implantable medical device.

25. The method of claim 24 , wherein adjusting the magnetic charging field in accordance with the parameter comprises determining an adjusted duty cycle using the parameter and the duty cycles in the memory.

26. The method of claim 24 , wherein the possible values for the parameter correspond to different battery charging currents, and wherein the duty cycle associated with each possible value is determined so as not to exceed the power dissipation limit in the implantable medical device.

27. The method of claim 15 , wherein the magnetic charging field is additionally adjusted in accordance with a voltage of the battery.

28. The method of claim 15 , wherein the parameter is periodically determined during the charging session, and wherein the magnetic charging filed is periodically adjusted in accordance with the periodically-determined parameter during the charging session.

Assignees

• Boston Scient Neuromodulation

Inventors

• Carbunaru Rafael
• Parramon Jordi
• Ozawa Robert
• Shi Jess
• Chen Joey
• Rahman Md Mizanur

Classifications

• A61N1/37217

  characterised by the communication link, e.g. acoustic or tactile · CPC title

• A61N1/3605

  Implantable neurostimulators for stimulating central or peripheral nerve system · CPC title

• A61N1/3787 Primary

  from an external energy source · CPC title

• A61N1/37205

  Microstimulators, e.g. implantable through a cannula · CPC title