Systems and methods for calibrating power measurements in an electrosurgical generator

• US 9,918,775 B2
• Filed: 03/03/2015
• Issued: 03/20/2018
• Est. Priority Date: 04/12/2011
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Gilbert, James A.
• Primary Examiner(s): Della, Jaymi
• Assistant Examiner(s): KIM, EUN HWA
• Application Number:
  US14/636,422
• Publication Number:
  US 20150164576A1
• Time in Patent Office: 1,113 Days
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 18/1233 with circuits for assuring patient safety
• CPC Class Codes: A61B 18/1445 at the distal end of a shaft, e.g. forceps or scissors at the end of a rigid rod
• CPC Class Codes: A61B 2018/00648 using more than one sensed parameter
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00827 Current
• CPC Class Codes: A61B 2018/00892 Voltage
• CPC Class Codes: H03H 17/0027 by means of a non-recursive filter
• CPC Class Codes: H03H 17/0251 Comb filters
• CPC Class Codes: H03H 17/0283 Filters characterised by the filter structure H03H17/0202, H03H17/0219 - H03H17/0248 take precedence
• CPC Class Codes: H03H 2017/0472 based on allpass structures
• CPC Class Codes: H03H 21/0012 Digital adaptive filters

Abstract

The disclosed electrosurgical systems and methods accurately determine the power actually applied to a load by using equalizers to calibrate the power measurements. The electrosurgical systems include an electrosurgical generator and an electrosurgical instrument coupled to the electrosurgical generator through an electrosurgical cable. The electrosurgical generator includes an electrical energy source, voltage and current detectors, equalizers that estimate the voltage and current applied to a load, and a power calculation unit that calculates estimated power based upon the estimated voltage and current. The methods of calibrating an electrosurgical generator involve applying a resistive element across output terminals of the electrosurgical generator, applying a test signal to the resistive element, measuring the magnitude and phase angle of voltage and current components of the test signal within the electrosurgical generator, estimating the magnitude and phase angle of the voltage and current at the resistive element using equalizers, and determining gain correction factors and minimum phase angles for the equalizers.

Claims

1. An electrosurgical generator comprising:

an electrical energy source;

an output stage coupled to the electrical energy source and configured to generate an electrosurgical signal based on electrical energy output by the electrical energy source;

a voltage detector coupled to the output stage and configured to detect a voltage at an output of the output stage;

a current detector coupled to the output stage and configured to detect a current at the output of the output stage;

an equalizer configured to estimate voltage and current applied to a load based on the detected voltage and current; and

a power calculation unit configured to calculate power applied to the load based on the estimated voltage and current,

wherein the equalizer includes a gain element and an all-pass filter and is configured to minimize an error between the calculated power and a power based on the detected voltage and current.

2. The electrosurgical generator according to claim 1, wherein the equalizer includes:

a voltage equalizer configured to estimate the voltage applied to the load; and

a current equalizer configured to estimate the current applied to the load.

3. The electrosurgical generator according to claim 1, wherein the equalizer is a parametric equalizer.

4. The electrosurgical generator according to claim 3, wherein the parametric equalizer is one of a shelving boost filter, a shelving cut filter, or a peak filter.

5. The electrosurgical generator according to claim 1, wherein the power calculation unit is configured to calculate actual power applied to the load.

6. The electrosurgical generator according to claim 1, further comprising analog-to-digital converters electrically coupled to the current and voltage detectors.

7. The electrosurgical generator according to claim 1, further comprising a digital signal processor, which includes the equalizer and the power calculation unit.