Linear power control with digital phase lock

A method for controlling power delivery in an electro-surgical instrument including a plurality of channels for delivery of an energy to a surgical site, and the method for controlling power comprising the acts of:

• measuring in a first time interval, the impedance of each of plurality of channels by sequentially isolating each of the plurality of channels from others of the plurality of channels;
• and
• computing in a second time interval differences between a target power and an actual power delivered to the plurality of channels to establish an amount by which to increase and to decrease the power in the plurality of channels;
• and
• modulating in the second time interval a driver signal for each of the plurality of channels to increase and to decrease an integer number of whole wavelengths of the driver signal to produce power levels on each of the plurality of channels, responsive to the computing act.

A method for controlling power delivery in an electro-surgical instrument including a plurality of channels for delivery of an energy to a surgical site, and the method for controlling power comprising the acts of:

• generating for a first of the plurality of channels a signal proportional to an actual power, and the signal proportional to the actual power derived from a product of low frequency signals proportional to current and voltage of the first of the plurality of channels and the low frequency signals derived from high frequency oscillating signals corresponding to a current and a voltage of a first oscillating signal of the first of the plurality of channels;
• computing differences between a target power and an actual power delivered to the first of the plurality of channels to establish an amount by which to increase and to decrease the power in the first oscillating signal;
• and
• modulating a driver signal generated by the driver to increase and to decrease an integer number of whole wavelengths of the driver signal to produce the first oscillating signal, responsive to said computing act.

An apparatus for power measurement in an electro-surgical instrument including a first channel for delivery of energy to a surgical site, and the apparatus for power measurement comprising:

• sensors for producing a voltage signal and a current signal proportional to a voltage and a current delivered by the first channel to the surgical site;
• a first summer and differencer for respectively, summing the voltage signal together with the current signal to produce a first signal and for differencing the voltage signal with the current signal to produce a second signal;
• a peak detector coupled to the first summer and differencer for forming a third and a fourth signal proportional respectively to peak voltage levels in the first and the second signals;
• a second summer and differencer for producing a fifth signal and a sixth signal proportional respectively to a difference and a sum of the third signal and the fourth signal;
• and
• a multiplier for multiplying the fifth and the sixth signals to produce a power signal equivalent to an actual power delivered by the first channel to the surgical site.