Electrosurgical generator

• US 5,836,943 A
• Filed: 08/23/1996
• Issued: 11/17/1998
• Est. Priority Date: 08/23/1996
• Status: Expired due to Term

• Current Assignee: Microline Surgical, Inc. (Hoya Corporation)
• Original Assignee: Team Medical, LLC
• Inventors: Miller, Scott A. III
• Primary Examiner(s): PEFFLEY, MICHAEL F
• Application Number:
  US08/702,282
• Time in Patent Office: 816 Days
• Field of Search: 606/32-34, 606/35, 606/37-42
• US Class Current: 606/34
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 2018/0066 without feedback, i.e. open loop control
• CPC Class Codes: A61B 2018/0072 Current
• CPC Class Codes: A61B 2018/00726 Duty cycle
• CPC Class Codes: A61B 2018/00767 Voltage
• CPC Class Codes: A61B 2018/00827 Current

Abstract

An electrosurgical generator is disclosed that provides radio-frequency electrical waveforms for performing surgical operations on a tissue mass. The various aspects of the present invention are embodied in an electrosurgical generator that includes a DC regulator, an amplifier, an energy recovery circuit, and a method of controlling these components to generate a desired electrical waveform for an electrosurgical operation.

Claims

1. An electrosurgical generator for providing an output signal for use in the performance of a surgical operation on a tissue mass, comprising:

a) dc regulator means for converting a first dc signal from a power source into a second dc signal having a pre-determined voltage, including

inductive input means for reducing current ripple in the first dc signal,

capacitive energy storage means for storing and releasing energy,

switch means for alternately charging said capacitive energy storage means with the first dc signal and discharging said capacitive energy storage means to generate the second dc signal, and

inductive output means for reducing current ripple in the second dc signal;

b) amplifier means for converting the second dc signal into the output signal having a predetermined frequency; and

c) control means for providing control signals to the dc regulator means and said amplifier means for establishing at least one of said predetermined voltage and said predetermined frequency.

2. The electrosurgical generator of claim 1, wherein said electrosurgical generator further comprises a core material that magnetically couples said inductive input means and said inductive output means for substantially reducing current ripples in one of said inductive input means and said inductive output means.

3. The electrosurgical generator of claim 1, wherein said capacitive energy storage means comprises:

a first capacitor;

a second capacitor; and

isolation transformer means, for isolating the current of the first dc signal from the current of the second dc signal.

4. The electrosurgical generator of claim 3, wherein said isolation transformer means includes a primary winding connected in series with said first capacitor, said inductive input means, and said power source, and a secondary winding connected in series with said second capacitor, said inductive output means, and said amplifier means.

5. The electrosurgical generator of claim 3, further comprising a core material that magnetically couples said isolation transformer means, said inductive input means, and said inductive output means for substantially reducing current ripples in said inductive input means and said inductive output means.

6. The electrosurgical generator of claim 1, wherein said switch means comprises:

a transistor connecting a junction between said inductive input means and said capacitive energy storage means to a return current path for said power source; and

a diode connecting a junction between said capacitive energy storage means and said inductive output means to the return current path.

7. The electrosurgical generator of claim 1, wherein said switch means comprises:

a transistor connecting a junction between said capacitive storage means and said inductive output means to a return current path.

8. The electrosurgical generator of claim 1, wherein said switch means comprises:

a switching means capable of supporting current flow in both directions connecting a junction between said inductive input means and said capacitive energy storage means to a return current path for the power source,

a switching means capable of supporting current flow in both directions connecting a junction between said capacitive storage means and said inductive output means to the return current path.

9. The system described in claim 8 in which switching means is comprised of one or more transistors.

10. The electrosurgical generator of claim 1, wherein said amplifier means comprises:

an amplifier input inductor for reducing current ripple of the second dc signal;

a resonant circuit connectable across the tissue mass, where said resonant circuit is connected in series with said amplifier input inductor and includes an inductor and a capacitor; and

amplifier switch means for alternately connecting and disconnecting a current return path of said amplifier means to a junction between said input inductor and said resonant circuit thereby providing an output signal.

11. The electrosurgical generator of claim 10, wherein:

said inductor and said capacitor of said resonant circuit are selected to provide a substantially zero voltage across said amplifier switch means and a substantially zero instantaneous rate of change of voltage across said amplifier switch means prior to said connecting by said amplifier switch means thereby substantially reducing energy dissipation by said amplifier switch means.

12. The electrosurgical generator of claim 1, further comprising:

energy recovery means electrically connected to said amplifier switch means for selectively storing and releasing energy of the output signal.

13. The electrosurgical generator of claim 12 where the energy recovery means is comprised of:

energy storage means in connection with said resonant circuit;

energy recovery switching means in connection with the control means, which alternately directs excess energy form the resonant circuit to the energy recovery storage means, and returns the excess energy to the amplifier means.

14. The electrosurgical generator of claim 13 wherein the energy storage means is an inductor.

15. The electrosurgical generator of claim 13 wherein the switching means is a transistor.

16. An electrosurgical generator for providing an output signal for use in the performance of a surgical operation on a tissue mass, comprising:

a) dc regulator means for converting a first dc signal from a power source into a second dc signal having a pre-determined voltage;

b) amplifier means for converting the second dc signal into the output signal having a predetermined frequency, including

an input inductor for reducing current ripple in the second dc signal,

a resonant circuit connectable across the tissue mass, where said resonant circuit is connected in series with said amplifier input inductor and includes an inductor and a capacitor; and

switch means for alternately connecting and disconnecting a current return path of said amplifier to a junction between said input inductor and said resonant circuit; and

c) control means for establishing at least one of said predetermined voltage and said predetermined frequency.

17. The electrosurgical generator of claim 16, wherein:

said inductor and said capacitor of said resonant circuit are selected so as to provide a substantially zero voltage across said switch means and a substantially zero instantaneous rate of change of voltage across said switch means prior to said connecting by said switch means thereby substantially reducing energy dissipation by said switch means.

18. The electrosurgical generator of claim 16, wherein:

said switch means includes a transistor.

19. The electrosurgical generator of claim 16, further comprising:

energy recovery means electrically connected to said resonant circuit for selectively storing and releasing energy of the output signal.

20. The electrosurgical generator of claim 16, wherein said inductive input means has a first number of windings and where said inductor of said resonant circuit has a second number of windings, wherein said first number of windings is substantially equal to said second number of windings.

21. The electrosurgical generator of claim 19 wherein the energy recovery means is comprised of:

energy storage means in connection with said resonant circuit;

energy recovery switching means in connection with the control means, which alternately directs excess energy of the output signal to the energy recovery storage means, and returns the excess energy to the amplifier means.

22. The electrosurgical generator of claim 21 wherein the energy storage means is an inductor.

23. The electrosurgical generator of claim 21 wherein the switching means is a transistor.