ADAPTIVE RATE RECHARGING SYSTEM

• US 20130193914A1
• Filed: 01/24/2013
• Published: 08/01/2013
• Est. Priority Date: 01/27/2012
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Gaddam, Venkat R., Bornhoft, Reid K., Kelly, Kevin J., Olson, David P., Smith, Todd V.
• Granted Patent: US 9,270,134 B2
• Time in Patent Office: Days
• US Class Current: 320/108
• CPC Class Codes: A61N 1/3787 from an external energy source
• CPC Class Codes: H02J 2310/23 The load being a medical device, a medical implant, or a life supporting device
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 7/007 Regulation of charging or discharging current or voltage
• CPC Class Codes: H02J 7/00711 with introduction of pulses during the charging process

Abstract

Devices, systems, and techniques for selecting a period for charging an implantable rechargeable power source are disclosed. Implantable medical devices may include a rechargeable power source that can be transcutaneously charged. A system may control a charging module to begin charging the rechargeable power source of the implantable medical device with a high power level. The system may then determine an estimated heat loss based on power initially delivered to the rechargeable power source when beginning the charging. Based on this estimated heat loss during the initial period of recharging, the system may select a boost period that includes a duration of time that the rechargeable power source is charged with the high power level.

Claims

1. A method comprising:

controlling a charging module to begin charging a rechargeable power source of an implantable medical device with a high power level, wherein the high power level is higher than a non-zero low power level;

determining, by a processor, an estimated heat loss based on power initially delivered to the rechargeable power source when beginning the charging with the high power level;

selecting, by the processor, a boost period based on the estimated heat loss; and

continuing to control the charging module to charge the rechargeable power source with the high power level for a duration of the boost period.

2. The method of claim 1, further comprising:

comparing a high power charging time to the boost period, wherein the high power charging time is an elapsed time with which the rechargeable power source was charged with the high power level; and

terminating charging with the high power level when the high power charging time exceeds the duration of the boost period.

3. The method of claim 2, further comprising:

selecting the low power level when the high power charging time exceeds the boost period; and

charging the rechargeable power source with the low power level until the rechargeable power source is fully charged, wherein the low power level comprises a lower power level than the high power level.

4. The method of claim 1, wherein determining the estimated heat loss comprises:

calculating a power delivered to a primary coil of an external charging device;

calculating a power lost in the primary coil; and

subtracting the power lost in the primary coil and the power delivered to the rechargeable power source from the power delivered to the primary coil.

5. The method of claim 1, further comprising calculating the power delivered to the rechargeable power source by measuring an electrical current flowing to the rechargeable power source, measuring a voltage of the rechargeable power source, and multiplying the electrical current by the voltage.

6. The method of claim 1, wherein:

selecting the boost period comprises selecting one of a plurality of boost periods that corresponds to the estimated heat loss; and

the plurality of boost periods comprise different durations of time.

7. The method of claim 1, wherein the duration of the boost period is between approximately 5 minutes and 35 minutes.

8. The method of claim 1, further comprising:

generating a first electrical current in a primary coil of a charging device based on the high power level; and

inducing an electrical current in an implanted secondary coil to charge the rechargeable power source.

9. The method of claim 1, further comprising:

calculating, by the processor, an estimated cumulative thermal dose delivered to the patient during charging of the rechargeable power source over at least the duration of the boost period; and

selecting, by the processor, a subsequent power level for charging the rechargeable power source after the boost period based on the estimated cumulative thermal dose.

10. The method of claim 1, wherein the processor is housed by one of the implantable medical device or an external charging device.

11. The method of claim 1, wherein the high power level is a first power level, and wherein the method further comprises:

controlling the charging module to begin charging the rechargeable power source of an implantable medical device with a second power level different than the first power level;

determining, by the processor, an estimated heat loss for the second power level based on power delivered to the rechargeable power source when charging with the second power level;

selecting, by the processor, a boost period based on the estimated heat loss for the second power level;

calculating a first charge addition to the rechargeable power source for the first power level during the boost period of the first power level;

calculating a second charge addition to the rechargeable power source for the second power level during the boost period of the second power level;

determining a highest charge addition by comparing the first forecast charge addition to the second forecast charge addition; and

selecting, by the processor, the first power level for charging the rechargeable power source when the first power level is associated with the highest charge addition.

12. The method of claim 1, wherein the rechargeable power source comprises a negative electrode comprising lithium titanate.

13. The method of claim 1, wherein continuing to control the charging module to charge the rechargeable power source with the high power level comprises controlling the charging module to charge the rechargeable power source at a charge rate greater than approximately 0.5 C.

14. The method of claim 1, wherein continuing to control the charging module to charge the rechargeable power source with the high power level comprises controlling the charging module to charge the rechargeable power source at a charge rate greater than approximately 5.0 C.

15. The method of claim 1, wherein continuing to control the charging module to charge the rechargeable power source with the high power level comprises controlling the charging module to charge the rechargeable power source at a constant voltage greater than a full charge voltage of the rechargeable power source.

16. A system comprising:

a processor configured to;

control a charging module to begin charging a rechargeable power source of an implantable medical device with a high power level, wherein the high power level is higher than a non-zero low power level;

determine an estimated heat loss based on power initially delivered to the rechargeable power source when beginning to charge the rechargeable power source with the high power level;

select a boost period based on the estimated heat loss; and

continue to control the charging module to charge the rechargeable power source with the high power level for a duration of the boost period.

17. The system of claim 16, wherein the processor is configured to:

compare a high power charging time to the boost period, wherein the high power charging time is an elapsed time with which the rechargeable power source was charged with the high power level; and

terminate charging with the high power level when the high power charging time exceeds the duration of the boost period.

18. The system of claim 17, further comprising a charging module, wherein:

the processor is configured to select the low power level when the high power charging time exceeds the boost period;

the charging module is configured to charge the rechargeable power source with the low power level until the rechargeable power source is fully charged; and

the low power level comprises a lower power level than the high power level.

19. The system of claim 16, wherein the processor is configured to:

calculate a power delivered to a primary coil of an external charging device;

calculate a power lost in the primary coil; and

subtract the power lost in the primary coil and the power delivered to the rechargeable power source from the power delivered to the primary coil to determine the estimated heat loss.

20. The system of claim 19, wherein the processor is configured to multiply a measured electrical current flowing to the rechargeable power source by a measured voltage of the rechargeable power source to calculate the power delivered to the rechargeable power source.

21. The system of claim 16, further comprising a memory configured to store a plurality of boost periods each comprising different durations of time, wherein the processor is configured to select one of the plurality of boost periods that corresponds to the estimated heat loss.

22. The system of claim 16, wherein the duration of the boost period is between approximately 5 minutes and 35 minutes.

23. The system of claim 16, further comprising:

an external charging device configured to generate a first electrical current in a primary coil of the charging device based on the high power level;

a secondary coil configured to be implanted in a patient and produce a second electrical current induced by a magnetic field of the primary coil, wherein the secondary coil is associated with the rechargeable power source; and

a telemetry module configured to receive charging data from the implantable medical device, wherein the charging data comprises a measured electrical current flowing to the rechargeable power source and a measured voltage of the rechargeable power source.

24. The system of claim 16, wherein the processor is configured to:

calculate an estimated cumulative thermal dose delivered to the patient during charging of the rechargeable power source over at least the duration of the boost period; and

select a subsequent power level for charging the rechargeable power source after the boost period based on the estimated cumulative thermal dose.

25. The system of claim 16, wherein the processor is contained within one of the implantable medical device or a charging device configured to charge the rechargeable power source.

26. The system of claim 16, further comprising the rechargeable power source, wherein the rechargeable power source comprises a negative electrode comprising lithium titanate.

27. The system of claim 16, wherein the processor is configured to control the charging module to charge the rechargeable power source at a charge rate greater than approximately 0.5 C.

28. The system of claim 16, wherein the processor is configured to control the charging module to charge the rechargeable power source at a charge rate greater than approximately 5.0 C.

29. The system of claim 16, further comprising a charging module of the implantable medical device, wherein the charging module is configured to charge the rechargeable power source at a constant voltage greater than a full charge voltage of the rechargeable power source.

30. A computer-readable storage medium comprising instructions that cause at least one processor to:

control a charging module to begin charging a rechargeable power source of an implantable medical device with a high power level, wherein the high power level is higher than a non-zero low power level;

determine an estimated heat loss based on power initially delivered to the rechargeable power source when beginning the charging with the high power level;

select a boost period based on the estimated heat loss; and

continue to control the charging module to charge the rechargeable power source with the high power level for a duration of the boost period.

31. The computer-readable storage medium of claim 30, further comprising instructions that cause the at least one processor to:

compare a high power charging time to the boost period, wherein the high power charging time is an elapsed time with which the rechargeable power source was charged with the high power level; and

terminate charging with the high power level when the high power charging time exceeds the boost period.

32. The computer-readable storage medium of claim 31, further comprising instructions that cause the at least one processor to calculate the power delivered to the rechargeable power source by measuring an electrical current flowing to the rechargeable power source, measuring a voltage of the rechargeable power source, and multiplying the electrical current by the voltage, wherein the instructions that cause the at least one processor to determine the estimated heat loss comprise instructions that cause the at least one processor to:

calculate a power delivered to a primary coil of an external charging device;

calculate a power lost in the primary coil; and

subtract the power lost in the primary coil and the power delivered to the rechargeable power source from the power delivered to the primary coil.

33. A system comprising:

means for controlling a charging module to begin charging a rechargeable power source of an implantable medical device with a high power level, wherein the high power level is higher than a non-zero low power level;

means for determining an estimated heat loss based on power initially delivered to the rechargeable power source when beginning the charging with the high power level; and

means for selecting a boost period based on the estimated heat loss, wherein the means for controlling the charging module to begin charging the rechargeable power source comprises means for continuing to control the charging module to charge the rechargeable power source with the high power level for a duration of the boost period.