POWER CONVERTER FOR USE WITH IMPLANTABLE THERMOELECTRIC GENERATOR

• US 20070253227A1
• Filed: 03/05/2007
• Published: 11/01/2007
• Est. Priority Date: 04/26/2006
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Erbstoeszer, Blair, James, Kristofer J., Morita, Glenn
• Granted Patent: US 8,538,529 B2
• Time in Patent Office: Days
• US Class Current: 363/19
• CPC Class Codes: A61N 1/3785 generated by biological activity or substance, e.g. body movement
• CPC Class Codes: H02N 1/006 of the gap-closing type H02N1/004 takes precedence

Abstract

Method an apparatus for converting the output of a thermoelectric generator to voltages compatible with implantable medical devices is provided. One apparatus includes an implantable thermoelectric generator. The apparatus includes an input terminal for receiving an input voltage generated by a thermoelectric energy converter and a charging inductor connected in series with the input terminal. The apparatus also includes a switching Field Effect Transistor (FET) connected to the inductor, and a capacitor connected to the FET and the input terminal via a diode. The FET is switched with a frequency and duty cycle such that a voltage level at an output terminal is compatible with an implantable medical device. According to various embodiments, the FET is switched using a closed loop feedback system that controls the frequency and duty cycle based on an observed voltage level at the output terminal. Other aspects and embodiments are provided herein.

Claims

1. An apparatus, comprising:

a thermoelectric energy converter having an output to an input terminal;

a charging inductor connected in series with the input terminal;

a switching FET connected to the inductor; and

a capacitor connected to the FET and the input terminal via a diode, the capacitor adapted to accumulate charge;

wherein the FET is switched with a frequency and duty cycle such that a voltage level at an output terminal is compatible with an implantable medical device.

2. The apparatus of claim 1, wherein the capacitor has capacitance of 1 μ

F.

3. The apparatus of claim 1, wherein the input voltage generated by the thermoelectric generator is at most 100 μ

V.

4. The apparatus of claim 1, wherein power efficiency from the input terminal to the output terminal is at least 20%.

5. The apparatus of claim 1, wherein power efficiency from the input terminal to the output terminal is 30%.

6. The apparatus of claim 1, wherein the FET is switched with a frequency of 10 kHz.

7. The apparatus of claim 1, wherein the FET is switched with a duty cycle of at least 90%.

8. The apparatus of claim 1, wherein the FET is switched using a closed loop feedback system.

9. The apparatus of claim 8, wherein the closed loop feedback system controls the frequency and duty cycle based on an observed voltage level at the output terminal.

10. The apparatus of claim 9, wherein the frequency and duty cycle are controlled using pulse-width modulation.

11. The apparatus of claim 1, wherein the charging inductor includes a hand-wrapped wire inductor.

12. The apparatus of claim 1, wherein the charging inductor has 22 turns.

13. The apparatus of claim 1, wherein the charging inductor includes 34 gauge wire.

14. A method, comprising:

forming an input terminal for receiving an input voltage generated by a thermoelectric energy converter;

forming a charging inductor connected in series with the input terminal;

forming a switching FET connected to the inductor; and

forming a capacitor connected to the FET and the input terminal via a diode, the capacitor adapted to accumulate charge;

wherein the FET is switched with a frequency and duty cycle such that a voltage level at an output terminal is compatible with an implantable medical device.

15. The method of claim 14, wherein forming a charging inductor includes forming an inductor with 22 turns of 34 gauge wire.

16. The method of claim 14, wherein forming a switching FET includes forming a FET with a resistance of at most 40 milliohms when switched on.

17. The method of claim 14, wherein forming a capacitor includes forming the capacitor to have a capacitance of approximately 1 μ

F.

18. A method, comprising:

receiving an input voltage level generated by a thermoelectric energy converter;

switching a field effect transistor at a frequency to provide oscillating current to an inductor connected in series with the thermoelectric energy converter;

charging a capacitor using the inductor, converter and transistor to an output voltage level greater than the input voltage level; and

providing an output terminal across the capacitor with the output voltage level at the output terminal compatible with an implantable medical device.

19. The method of claim 18, wherein switching a field effect transistor includes switching the transistor at a frequency of approximately 10 kHz.

20. The method of claim 18, wherein switching a field effect transistor includes using a closed loop feedback system to control switching frequency based on an observed voltage level at the output terminal.