Method of minimizing interruptions to implantable medical device recharging
View Patent ↗A system and method of controlling the charging of the battery of a medical device using a remote inductive charger, with the method utilizing both a relatively fast closed-loop charging control based on a proxy for a target power transmission value in conjunction, and a slower closed-loop control based on an actual measured transmission value to control a charging power level for charging the medical device.
1. A method for charging a rechargeable battery in a medical device using an external charger, said method comprising the steps of:
wirelessly transmitting a power signal from the external charger to the medical device, said power signal including power for charging the rechargeable battery;
in the medical device, measuring a value of a first variable relating to the power signal received by the medical device from the external charger;
transmitting the value of the first variable from the medical device to the external charger concurrent with wirelessly receiving the power signal;
in the external charger, measuring a value of a second variable relating to the power signal transmitted by the external charger to the medical device; and
adjusting the power signal transmitted from the external charger to the medical device at least partly based on values of both said first variable and said second variable.
2. The method of claim 1 , wherein the value of said first variable is wirelessly transmitted to said external charger by said medical device.
3. The method of claim 2 , wherein said step of adjusting includes the steps of: said external charger calculating an updated power signal for transmitting to said medical device using said first variable and said second variable; and said external charger transmitting said updated power signal to said medical device.
4. The method of claim 1 , wherein said step of adjusting includes the steps of: said external charger calculating an updated power signal for transmitting to said medical device using said first variable and said second variable; and said external charger transmitting said updated power signal to said medical device.
5. The method of claim 1 , wherein said step of adjusting includes the steps of:
over a first time interval, calculating a power of the power signal transmitted from the external charger to the medical device based on a value of said second variable; and
receiving a value of said first variable from the medical device regularly over a second interval longer than said first interval, wherein
when a value of the first variable is received from the medical device, the step of calculating the power of the power signal transmitted is adjusted according to the value of the first variable as compared to a target value for the first variable.
6. The method of claim 5 , wherein the amount that the step of calculating the power is adjusted is based on a standard deviation of a historical accumulation of values of the first variable.
7. The method of claim 5 , wherein the amount that the step of calculating the power is adjusted is based on a standard deviation of a historical accumulation of values of the first variable multiplied by a factor based on a status of the medical device.
8. The method of claim 1 , wherein said first variable is a measurement of a rectified voltage in the medical device and wherein said second variable is a power of the power signal transmitted by the external charger based on a measurement of the voltage and current provided at an output of the external charger.
9. The method of claim 1 , wherein said medical device is an implantable medical device for implanting in the body of a patient for performing electrical stimulation and wherein said external charger is provided outside of the body of the patient for inductively transmitting power to said medical device using the power signal.
10. A system for implementing the method of claim 1 , comprising the external charger and the medical device.
11. A method for charging a rechargeable battery in an implantable medical device using an external charger, said method comprising the steps of:
inductively transmitting power from a primary coil of the external charger to a secondary coil of the medical device;
in the medical device, measuring a value of a rectified voltage of the secondary coil obtained from the power received from the external charger;
periodically transmitting the value of the rectified voltage or a derivation thereof from the medical device to the external charger;
in the external charger, determining a value of the power transmitted by the external charger to the medical device; and
in the external charger, adjusting the power transmitted from the external charger to the medical device at least partly based on the determined value of the power transmitted by the external charger to the medical device, wherein
when the value of the rectified voltage or derivation thereof is received by the external charger, the step of adjusting the power transmitted from the external charger to the medical device is based on the value of the rectified voltage or derivation thereof as compared to a desired value.
12. The method of claim 11 , wherein said desired value is determined from a standard deviation of a number of values of the rectified voltage or the derivation thereof.
13. The method of claim 11 , wherein said desired value is determined from a standard deviation of a number of values of the rectified voltage, or the derivation thereof, multiplied by a factor based on a status of the medical device.
14. The method of claim 11 , wherein said step of transmitting the value of the rectified voltage or the derivation thereof is done via the inductive link between the external charger and the medical device.
15. The method of claim 11 , wherein said step of transmitting the value of the rectified voltage or the derivation thereof is done via an RF link between the external charger and the medical device.
16. A system for implementing the method of claim 11 , comprising the external charger and the medical device.
17. A method for charging a rechargeable battery in an implantable medical device using an external charger, said method comprising the steps of:
inductively transmitting power from a primary coil of the external charger to a secondary coil of the medical device;
in the medical device, measuring a first variable representing the power received from the external charger;
periodically transmitting the value of the first variable from the medical device to the external charger;
in the external charger, determining a value of a second variable representing the power transmitted by the external charger to the medical device;
in the external charger, adjusting the power transmitted from the external charger to the medical device at least partly based on the determined value of the second variable; and
in the external charger, statistically analyzing a plurality of the values of the first variable received from the medical device, wherein
when the value of the first variable is received by the external charger, adapting the step of adjusting the power transmitted from the external charger to the medical device based on the value of the rectified voltage as compared to a desired value of the rectified voltage that is determined at least partly based on a result of the statistically analyzing step.
18. The method of claim 17 , wherein said adapting said adjusting the power transmitted from the external charger to the medical device step is also based on a status of the medical device.
19. The method of claim 17 , wherein said step of statistically analyzing includes the step of determining a standard deviation of the plurality of the values of the first variable, and wherein the desired value of the rectified voltage is determined at least partly based on the determined standard deviation.
20. A system for implementing the method of claim 17 , comprising the external charger and the medical device.
21. A method of providing a neurostimulation therapy to a patient, comprising the steps of:
providing an implantable medical device having a rechargeable battery and being implanted in a patient;
using said implantable medical device for driving at least one electrode implanted in the patient to stimulate at least one nerve of the patient; and
recharging said battery using an external charger, said recharging including the steps of:
wirelessly transmitting power from the external charger to the medical device;
in the medical device, measuring a value of a first variable relating to the power received by the medical device from the external charger;
in the external charger, measuring a value of a second variable relating to the power transmitted by the external charger to the medical device; and
adjusting the power transmitted from the external charger to the medical device at least partly based on values of both said first variable and said second variable.
22. A method for charging a rechargeable battery in a medical device using an external charger, said method comprising the steps of:
wirelessly transmitting an inductive power signal from the external charger to the medical device, said power signal including power for charging the rechargeable battery;
in the medical device, measuring a value of a first variable relating to the power signal received by the medical device from the external charger;
transmitting the value of the first variable from the medical device to the external charger using an RF transmission;
in the external charger, measuring a value of a second variable relating to the power signal transmitted by the external charger to the medical device; and
adjusting, in the external charger, the inductive power signal transmitted from the external charger to the medical device at least partly based on values of both said first variable and said second variable.