Wireless power transfer circuit for a rechargeable implantable pulse generator

Patent metadata

Field	Value
Publication number	US-11547862-B2
Application number	US-201916676197-A
Country	US
Kind code	B2
Filing date	Nov 6, 2019
Priority date	Apr 15, 2019
Publication date	Jan 10, 2023
Grant date	Jan 10, 2023

Abstract

A charging energy control system includes an implantable medical device (IMD) and an external charger for effectuating wireless power transfer. The IMD receives charging energy to recharge a battery during an ON period and rejects the charging energy during an OFF period. A series switch is disposed between the IMD's coil and rectifier circuitry that is controlled by voltage regulation circuitry operative to generate a clamp control signal configured to detune the coil in the OFF state.

First claim

The invention claimed is:

1. An implantable medical device (IMD) configured to provide stimulation therapy to a patient, the IMD comprising:
a rechargeable battery;
pulse generating circuitry powered by the rechargeable battery;
an inductive coupling element including at least one inductor (L) and at least one capacitor (C) coupled to the at least one inductor in a series LC circuit configuration operative to accept radio frequency (RF) power from an external charger, the series LC circuit configuration defining a first electrical node at a terminal of the at the least one inductor and a second electrical node at a terminal of the at least one capacitor;
a bridge rectifier operative to generate a charging voltage at an output node of the bridge rectifier from an induced voltage provided by the inductive coupling element when magnetically coupled to the external charger to receive the RF power;
a series switch disposed between the first electrical node of the series LC circuit configuration and the bridge rectifier;
voltage regulation circuitry operative to regulate a level of the charging voltage generated at the output node of the bridge rectifier for charging the rechargeable battery; and
a coil clamp circuit configured to change the series switch to an OFF state based on an output of the voltage regulation circuitry to detune the inductive coupling element, whereby a high voltage condition is prevented from developing in the series LC circuit configuration of the inductive coupling element.

2. The IMD as recited in claim 1 , wherein the series switch comprises an N-channel metal oxide semiconductor (NMOS) field-effect transistor (FET) device driven by a gate voltage derived from the series LC circuit configuration in an ON state.

3. The IMD as recited in claim 2 , wherein the NMOS device is opened in the OFF state by clamping the gate voltage to a ground using a first FET device of the coil clamp circuit that is driven by a clamp control signal generated by the voltage regulation circuitry.

4. The IMD as recited in claim 3 , wherein the coil clamp circuit comprises a second FET device disposed in a parallel circuit configuration with the first FET device, the second FET device coupled to the second electrical node of the series LC circuit configuration and driven by the clamp control signal generated by the voltage regulation circuitry.

5. The IMD as recited in claim 1 , wherein the voltage regulation circuitry comprises a first comparator configured to compare a target voltage level of the charging voltage generated by the bridge rectifier with an internal reference voltage associated with the first comparator.

6. The IMD as recited in claim 5 , wherein an output of the first comparator is coupled to a grounded loading resistor for preventing asserting a logic high value of the clamp control signal until an operating voltage of the first comparator comprising the target voltage level is reached.

7. The IMD as recited in claim 5 , wherein the voltage regulation circuitry comprises a second comparator configured to compare an over-voltage shutoff level that is greater than the target voltage level by a select amount with an internal reference voltage associated with the second comparator.

8. The IMD as recited in claim 7 , wherein an output of the second comparator is coupled to a grounded loading resistor for preventing asserting a logic high value of the clamp control signal until an operating voltage of the second comparator comprising the over-voltage shutoff level is reached.

9. The IMD as recited in claim 1 , wherein the inductive coupling element is open when the series switch is in the OFF state.

10. The IMD as recited in claim 1 , wherein the inductive coupling element is not connected to ground when the series switch is in the OFF state.

11. A stimulation system, comprising:
an implantable medical device (IMD) implanted within a patient to provide stimulation therapy to a specific tissue of the patient, the IMD comprising a rechargeable battery and pulse generating circuitry powered by the rechargeable battery; and
an external charger including a primary coil configured to effectuate a near field coupling relationship with the IMD when positioned proximate to a region of the patient having the IMD,
wherein the IMD includes:
an inductive coupling element comprising at least one inductor (L) and at least one capacitor (C) coupled to the at least one inductor in a series LC circuit configuration operative to accept radio frequency (RF) power from the external charger, the series LC circuit configuration defining a first electrical node at a terminal of the at least one inductor and a second electrical node at a terminal of the at least one capacitor;
a bridge rectifier operative to generate a charging voltage at an output node of the bridge rectifier from an induced voltage provided by the inductive coupling element when magnetically coupled to the external charger to receive the RF power;
a series switch disposed between the first electrical node of the series LC circuit configuration and the bridge rectifier;
voltage regulation circuitry operative to regulate a level of the charging voltage generated at the output node of the bridge rectifier for charging the rechargeable battery; and
a coil clamp circuit configured to change the series switch to an OFF state based on an output of the voltage regulation circuitry to detune the inductive coupling element, whereby a high voltage condition is prevented from developing in the series LC circuit configuration of the inductive coupling element.

12. The stimulation system as recited in claim 11 , wherein the inductive coupling element is disposed in a header portion so that only two feedthroughs are utilized in connecting the inductive coupling element to a first input node of the bridge rectifier via the series switch and to a second input node of the bridge rectifier, and further wherein the series switch, the bridge rectifier, the voltage regulation circuitry and the coil clamp circuit are disposed in a device housing of the IMD to which the header portion is hermetically coupled.

13. The stimulation system as recited in claim 12 , wherein the external charger comprises:
a clamp detector configured to detect clamping of the series LC circuit configuration due to at least one of: (i) detuning the series LC circuit configuration caused by opening the series switch, and (ii) assertion of a voltage control signal generated responsive to monitoring a target voltage level of the charging voltage generated by the bridge rectifier; and
a controller for monitoring a rate of occurrence of clamping at the series LC circuit configuration and, responsive to the monitoring of the rate of occurrence of clamping, for modifying a frequency of the RF power generated by the primary coil.

14. The stimulation system as recited in claim 13 , wherein the series switch comprises an N-channel metal oxide semiconductor (NMOS) field-effect transistor (FET) device driven by a gate voltage derived from the series LC circuit configuration in an ON state.

15. The stimulation system as recited in claim 14 , wherein the NMOS device is opened in the OFF state by clamping the gate voltage to a ground using a first FET device of the coil clamp circuit that is driven by a clamp control signal generated by the voltage regulation circuitry.

16. The stimulation system as recited in claim 15 , wherein the coil clamp circuit comprises a second FET device disposed in a parallel circuit configuration with the first FET device, the second FET device coupled to the second electr

Assignees

• Advanced Neuromodulation Systems Inc

Inventors

• Winstrom William

Classifications

• A61N1/362

  Heart stimulators (heart defibrillators A61N1/39) · CPC title

• A61N1/0543

  Retinal electrodes · CPC title

• H02J50/80

  involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices · CPC title

• A61N1/3787 Primary

  from an external energy source · CPC title

• H02J50/005

  Mechanical details of housing or structure aiming to accommodate the power transfer means, e.g. mechanical integration of coils, antennas or transducers into emitting or receiving devices · CPC title