Power monitoring circuitry and method for reducing leakage current in RF generators

• US 10,363,086 B2
• Filed: 10/30/2015
• Issued: 07/30/2019
• Est. Priority Date: 10/31/2014
• Status: Active Grant

• Current Assignee: Medtronic Advanced Energy LLC (Medtronic Plc)
• Original Assignee: Medtronic Advanced Energy LLC (Medtronic Plc)
• Inventors: Smith, Jesse A., Hubelbank, David, Reaume, Jeffrey S.
• Primary Examiner(s): Peffley, Michael F
• Assistant Examiner(s): Vahdat, Khadijeh A
• Application Number:
  US14/927,969
• Publication Number:
  US 20160120591A1
• Time in Patent Office: 1,369 Days
• Field of Search: 606 33- 41
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 18/1233 with circuits for assuring patient safety
• CPC Class Codes: A61B 18/1402 Probes for open surgery
• CPC Class Codes: A61B 18/148 having a short, rigid shaft for accessing the inner body transcutaneously, e.g. for neurosurgery or arthroscopy
• CPC Class Codes: A61B 2018/0016 Energy applicators arranged in a two- or three dimensional array
• CPC Class Codes: A61B 2018/00178 Electrical connectors
• CPC Class Codes: A61B 2018/00607 Coagulation and cutting with the same instrument
• CPC Class Codes: A61B 2018/00642 with feedback, i.e. closed loop control
• CPC Class Codes: A61B 2018/00648 using more than one sensed parameter
• CPC Class Codes: A61B 2018/00666 using a threshold value
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00767 Voltage
• CPC Class Codes: A61B 2018/00827 Current
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 2018/00892 Voltage
• CPC Class Codes: A61B 2018/124 switching the output to different electrodes, e.g. sequentially
• CPC Class Codes: A61B 2018/1253 monopolar
• CPC Class Codes: A61B 2018/126 bipolar
• CPC Class Codes: A61B 2018/1286 having a specific transformer

Abstract

An electrosurgical unit having power monitoring circuitry for reducing leakage current in an electrosurgical unit. The electrosurgical unit includes a power source configured to produce direct current, an RF waveform generator configured to convert the direct current into an RF signal, a voltage sensor configured to measure DC input voltage to the RF waveform generator, a current sensor configured to measure output current feedback, and a processor. The processor is configured to estimate output voltage feedback based at least upon the measured DC input voltage and the measured output current feedback, and output a control signal to control the DC input voltage to the RF waveform generator, the control signal based at least upon the estimated output voltage and the output current feedback.

Claims

1. An electrosurgical unit comprising:

a power source configured to produce direct current;

a radiofrequency (RF) waveform generator configured to convert the direct current (DC) into an RF signal;

a voltage sensor configured to measure a DC input voltage to the RF waveform generator;

a current sensor configured to measure an output alternating current (AC) current feedback; and

a processor configured to;

estimate output AC voltage feedback based at least upon the measured DC input voltage and the measured output AC current feedback, the estimated output AC voltage feedback is not based at least in part on measurement of the output AC voltage feedback; and

output a control signal to control the DC input voltage to the RF waveform generator, the control signal based at least upon the estimated output AC voltage feedback.

2. The electrosurgical unit of claim 1, wherein the RF waveform generator comprises a bridge circuit configured to generate the RF signal from the DC input voltage adjusted by the processor.

3. The electrosurgical unit of claim 2, where the voltage sensor measures the DC input voltage to the bridge circuit.

4. The electrosurgical unit of claim 1, further comprising an isolation barrier in electrical communication with the RF waveform generator.

5. The electrosurgical unit of claim 1, wherein the processor estimates the output AC voltage feedback using a statistical analysis mechanism.

6. The electrosurgical unit of claim 5, wherein the statistical analysis mechanism is a multiple linear regression analysis where analog to digital conversion (ADC) readings for the measured DC input voltage and alternating current root-mean-square (AC RMS) readings for the measured output AC current feedback are used as independent variables.

7. The electrosurgical unit of claim 1, wherein the estimated output AC voltage feedback is not based at least in part on measurement of a DC input current to the RF waveform generator.

8. A method for controlling power of radiofrequency (RF) system, the method comprising;

measuring a direct current (DC) input voltage to an RF waveform generator;

measuring an output alternating current (AC) current feedback;

estimating output AC voltage feedback based at least upon the measured DC input voltage and the measured output AC current feedback, the estimated output AC voltage feedback is not based at least in part on measurement of the output AC voltage feedback; and

outputting a control signal to control the DC input voltage to the RF waveform generator, the control signal based at least upon the estimated output AC voltage feedback.

9. The method of claim 8, wherein estimating the output AC voltage feedback comprises using a statistical analysis mechanism.

10. The method of claim 9, wherein the statistical analysis mechanism is a multiple linear regression analysis where analog to digital conversion (ADC) readings for the measured DC input voltage and alternating current root-mean-square (AC RMS) readings for the measured output AC current feedback are used as independent variables.

11. The method of claim 10, further comprising using the measured output AC current feedback to compensate for non-linear behavior in the estimated output AC voltage feedback.

12. The method of claim 8, wherein the estimated output AC voltage feedback is not based at least in part on measurement of a DC input current to the RF waveform generator.