Real-time arc control in electrosurgical generators
An electrosurgical generator is disclosed. The generator includes a radio frequency output stage configured to generate a radio frequency waveform and a sensor circuit configured to measure a property of the radio frequency waveform during a predetermined sampling period to determine whether an arc event has occurred. The generator also includes a controller configured to determine a total charge and/or total energy deposited by the radio frequency waveform during the predetermined sampling period associated with the arc event. The controller is further configured to adjust the output of the electrosurgical generator based on at least one parameter to limit arcing.
1. An electrosurgical generator comprising:
a radio frequency output stage configured to generate at least one radio frequency waveform having a voltage waveform and a current waveform;
a sensor circuit configured to determine at least one property of each of the voltage waveform and the current waveform during a predetermined sampling period; and
a controller configured to compare the at least one property of each of the voltage waveform and the current waveform on a time scale substantially equal to one-half radio frequency cycle of the at least one radio frequency waveform on a time scale substantially equal to one-half radio frequency cycle of the at least one radio frequency waveform to determine at least one deviation between the at least one property of each of the voltage waveform and the current waveform indicative of an arc event, the controller further configured to determine at least one of total charge, total energy and duration of the arc event based on the at least one deviation,
wherein the controller includes a total charge calculator module configured to temporally integrate the voltage waveform to determine the total charge deposited by the at least one radio frequency waveform during the predetermined sampling period.
2. The electrosurgical generator according to claim 1 , wherein the controller is further configured to adjust the output of the electrosurgical generator based on the at least one deviation.
3. The electrosurgical generator according to claim 2 , wherein the controller includes a total energy calculator module configured to temporally integrate total power deposited by the at least one radio frequency waveform to determine the total energy deposited by the at least one radio frequency waveform during the predetermined sampling period.
4. The electrosurgical generator according to claim 1 , further comprising:
a shunt capacitor disposed between active and return terminals of the electrosurgical generator.
5. The electrosurgical generator according to claim 4 , wherein the controller includes a total energy calculator module configured to temporally integrate product of total charge deposited by the at least one radio frequency waveform and voltage across the shunt capacitor to determine the total energy deposited by the at least one radio frequency waveform during the predetermined sampling period.
6. The electrosurgical generator according to claim 4 , wherein the controller is configured to determine a desired amount of energy to be deposited into tissue per arc event based on a formula E=CV 2 /2+LI 2 /2, wherein E is the desired energy, C is capacitance of the shunt capacitor, L is inductance of a series inductor, I is current and V is voltage measured across the shunt capacitor.
7. The electrosurgical generator according to claim 4 , further comprising:
a resistor and an inductor coupled in series with the active terminal.
8. A method for operating an electrosurgical generator, comprising:
generating at least one radio frequency waveform having a voltage waveform and a current waveform;
determining at least one property of each of the voltage waveform and the current waveform during a predetermined sampling period;
measuring amplitude of the voltage waveform across a series resistor of the electrosurgical generator during the sampling period;
comparing the at least one property of each of the voltage waveform and the current waveform on a time scale substantially equal to one-half radio frequency cycle of the at least one radio frequency waveform to determine at least one deviation between the at least one property of each of the voltage waveform and the current waveform indicative of an arc event
determining at least one of total charge, total energy and duration of the arc event based on the at least one deviation; and
temporally integrating voltage across the series resistor to determine total charge deposited into tissue by the at least one radio frequency waveform during the sampling period.
9. The method according to claim 8 , further comprising:
temporally integrating power of the at least one radio frequency waveform during the sampling period to determine total energy deposited into tissue by the at least one radio frequency waveform during the sampling period.
10. The method according to claim 8 , further comprising:
measuring voltage across a shunt capacitor disposed between active and return terminals of the electrosurgical generator during the sampling period; and
temporally integrating a product of the total charge and the voltage across the shunt capacitor to determine total energy deposited into tissue by the at least one radio frequency waveform during the sampling period.
11. The method according to claim 10 , further comprising:
calculating a desired amount of energy to be deposited into tissue per arc event to limit the arc event; and
adjusting output of the electrosurgical generator based on the desired maximum amount of energy to be deposited into tissue per arc event.
12. The method according to claim 11 , wherein calculating the desired amount of energy is based on a formula E=CV 2 /2+LI 2 /2, wherein E is the desired energy, C is capacitance of the shunt capacitor, L is inductance of a series inductor, I is current and V is voltage measured across the shunt capacitor.