Abstract: A surgical generator configured to output a high-frequency alternating voltage to a surgical ultrasound instrument. An oscillator generates a driving oscillation for an inverter generating high-frequency voltage being for the surgical instrument. A matching-coil emulation device includes a correction device acting on the driving oscillation. The correction device includes a mixing unit and a feedback circuit, modifying the driving oscillation supplied to the inverter. An estimator calculates a virtual current which would flow in the emulated matching-coil if it were present, based on this and a measured output voltage an artificial phase shift is determined for steering of the oscillator. Thereby, the transfer function is reshaped mimicking that of a physical matching coil. Accordingly, a bulky matching coil that must be precisely tuned to the ultrasound instrument and restricts use of newer and different ultrasound instruments is no longer needed.

Abstract: An electrosurgical generator for an electrosurgical instrument includes a DC voltage supply and a high-voltage inverter that generates a high-frequency AC voltage having a variable voltage and frequency that is output at an output for the connection of the electrosurgical instrument. The inverter is configured as a multilevel inverter and includes a plurality of inverter cells connected in a cascaded manner that are driven by a control device. Thanks to the cascading, switching losses incurred in the power semiconductors are reduced, both in terms of value (through the divided and thus lower voltage) and in terms of frequency (through the reduced switching frequency).