Circuit and method for reducing stored energy in an electrosurgical generator

• US 20070093801A1
• Filed: 10/21/2005
• Published: 04/26/2007
• Est. Priority Date: 10/21/2005
• Status: Active Grant

• Current Assignee: Covidien AG (Medtronic Plc)
• Original Assignee: Covidien AG (Medtronic Plc)
• Inventors: Behnke, Robert
• Granted Patent: US 8,734,438 B2
• Time in Patent Office: Days
• US Class Current: 606/34
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 18/1233 with circuits for assuring patient safety
• CPC Class Codes: A61B 2017/00119 alarm; indicating an abnormal situation

Abstract

A circuit for discharging stored energy in an electrosurgical generator is disclosed. The circuit includes a pulse width modulator for controlling a high voltage power supply, an error signal generating circuit configured for delivering an error signal as a difference between an output signal voltage with a feedback voltage generated by the high voltage power supply. The error signal is transmitted to the pulse width modulator. The circuit further includes a switching circuit configured to switch in a load in parallel with an output of the high voltage power supply when the error signal is lesser than a first predetermined threshold to discharge the output.

Claims

1. A circuit for discharging stored energy in an electrosurgical generator comprising:

a pulse width modulator for controlling a high voltage power supply;

an error signal generating circuit configured for delivering an error signal as a difference between an output signal voltage with a feedback voltage generated by the high voltage power supply, the error signal being transmitted to the pulse width modulator; and

a switching circuit configured to switch in a load in parallel with an output of the high voltage power supply when the error signal is lesser than a first predetermined threshold to discharge the output.

2. A circuit as in claim 1, wherein the first predetermined threshold is 0.5V.

3. A circuit as in claim 1, wherein the pulse width modulator turns off if the error signal is below a second predetermined threshold.

4. A circuit as in claim 3, wherein the second predetermined threshold is 0.7V.

5. A circuit as in claim 1, further comprising:

at least one diode for directing current from the high voltage power source.

6. An active discharge circuit as in claim 1, wherein the switching circuit comprises:

a resistive element; and

a switching component.

7. An active discharge circuit as in claim 6, wherein the switching component is a transistor.

8. An active discharge circuit as in claim 7, wherein the transistor is selected from the group consisting of a field-effect transistor (FET), a metal-oxide semiconductor field-effect transistor (MOSFET), and an insulated gate bipolar transistor (IGBT).

9. An active discharge circuit as in claim 6, wherein the resistive element has a resistance of 5 Ohms.

10. An electrosurgical generator comprising:

a high voltage power source for generating direct current;

a radio frequency output stage for converting direct current into radio frequency energy; and

a circuit comprising;

a pulse width modulator for controlling a high voltage power supply;

an error signal generating circuit configured for delivering an error signal as a difference between an output signal voltage with a feedback voltage generated by the high voltage power supply, the error signal being transmitted to the pulse width modulator; and

a switching circuit configured to switch in a load in parallel with an output of the high voltage power supply when the error signal is lesser than a first predetermined threshold to discharge the output.

11. An electrosurgical generator as in claim 10, wherein the first predetermined threshold is 0.5V.

12. An electrosurgical generator as in claim 10, wherein the pulse width modulator turns off if the error signal is below a second predetermined threshold.

13. An electrosurgical generator as in claim 12, wherein the second predetermined threshold is 0.7V.

14. An electrosurgical generator as in claim 10, wherein the active discharge circuit further comprises:

at least one diode for directing current from the high voltage power source.

15. An electrosurgical generator as in claim 10, wherein the switching circuit comprises:

a resistive element; and

a switching component.

16. An electrosurgical generator as in claim 15, wherein the switching component is a transistor.

17. An electrosurgical generator as in claim 16, wherein the transistor is selected from the group consisting of a field-effect transistor (FET), a metal-oxide semiconductor field-effect transistor (MOSFET), and an insulated gate bipolar transistor (IGBT).

18. An electrosurgical generator as in claim 15, wherein the resistive element has a resistance of 5 Ohms.

19. A method for discharging energy stored in a circuit in an electrosurgical generator, comprising the steps of:

deriving an error signal as a difference between an output setpoint voltage with a feedback voltage generated by a high voltage power supply;

comparing the error signal with a first predetermined threshold;

switching on a load in parallel with an output of the high voltage power supply when the error signal is lesser than a first predetermined threshold to discharge the output; and

switching on a pulse width modulator if the error signal is above a second predetermined threshold.

20. A method as in claim 19, wherein the first predetermined threshold is 0.5V.

21. A method as in claim 19, wherein the second predetermined threshold is 0.7V.

22. A method as in claim 19, further comprising:

at least one diode for directing current from the high voltage power source.

23. A method as in claim 19, wherein the switching circuit comprises:

a resistive element; and

a switching component.

24. A method as in claim 23, wherein the switching component is a transistor.

25. A method as in claim 24, wherein the transistor is selected from the group consisting of a field-effect transistor (FET), a metal-oxide semiconductor field-effect transistor (MOSFET), and an insulated gate bipolar transistor (IGBT).

26. A method as in claim 25, wherein the resistive element has a resistance of 5 Ohms.