Dual-Frequency Electrosurgical Generator for Cross-Current Control
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Solution Overview
Problem
Existing electrosurgical generators face challenges in dual activation scenarios due to interference between high-voltage outputs, leading to unwanted cross-currents and difficulties in precise control of energy delivery to electrosurgical instruments.
Innovation Solution
An electrosurgical generator with dual HF generation units operating at different frequencies, coupled with a central control unit and an observer unit that calculates working currents indirectly from measurable total currents, allowing for improved control of energy delivery and reduced interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate electrosurgical generators are used for each instrument to enable dual activation, then the ability to perform multiple surgery tasks simultaneously is improved, but interference between outputs occurs and cross-currents develop in the body
Solution Approach 1:
The patent combines multiple HF generation units into a single electrosurgical generator system with a shared control unit. This merging approach allows dual activation of electrosurgical instruments while maintaining centralized control over frequency assignment and power distribution, thereby preventing cross-currents and interference that would occur with completely separate generators.
Solution Approach 2:
The system assigns different fundamental frequencies to each output channel of the HF generation units. By changing the frequency parameter for each output, the system enables simultaneous operation of multiple instruments without interference, as the different frequencies prevent beat phenomena and allow independent control of each channel.
2Adaptability or versatility
If a single electrosurgical generator with dual inverters and output stages is employed, then dual activation is enabled, but avoiding unwanted interference remains difficult
Solution Approach 1:
The HF generation units are configured to output voltages at different fundamental frequencies for each channel. This parameter differentiation allows the system to provide dual output capability while eliminating interference between channels, as the distinct frequencies prevent cross-talk and beat phenomena that plague systems using identical frequencies.
Solution Approach 2:
The control unit continuously monitors the operation of each output channel and adjusts the HF generation parameters accordingly. This feedback mechanism ensures that interference is detected and corrected in real-time, maintaining stable dual output operation and preventing harmful cross-currents.
3Measurement precision
If power measurement is performed over both outputs, then total power monitoring is achieved, but the true power distribution between each output remains unknown and settings must be identical
Solution Approach 1:
The measurement system is segmented to independently monitor each output channel. By separating the measurement functions for each HF generation unit and their respective outputs, the system can provide both total power monitoring and individual power distribution data, eliminating the information loss that occurs with aggregated measurements.
Solution Approach 2:
The control unit receives separate measurement data from each output channel and uses this feedback to independently adjust and monitor power distribution. This allows the system to maintain identical or different settings for each output while providing complete visibility into individual power levels and their contribution to total power output.
4Reliability
If discrete Fourier transformation with Goertzel type filter is used to detect cross-conductance, then safety detection is achieved, but precise determination of working current is not enabled
Solution Approach 1:
The system uses DFT with Goertzel type filters to detect cross-conductance and generates feedback signals that enable precise calculation of working currents. The detection mechanism provides reliability by identifying unsafe conditions, while the associated measurement and calculation capabilities simultaneously deliver precise working current determination for each output channel.
Solution Approach 2:
The system analyzes multiple frequency parameters simultaneously using DFT techniques. By examining the frequency spectrum and identifying beat frequencies indicative of cross-conductance, the system achieves both safety detection and precise working current measurement through sophisticated parameter analysis rather than simple threshold detection.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables precise determination of individual working currents for each output, enhancing control over energy delivery, improving operational safety, and reducing risks associated with cross-currents and over-currents.
Implementation Method 1
a first HF generation unit supplying a first high-frequency alternating voltage having a first frequency to a first output, a second HF generation unit supplying a second high-frequency alternating voltage having a second frequency which is different from the first frequency to a second output
Implementation Method 2
an observer unit being configured for an indirect determination of the first and second working currents based on measured values obtained by a dual measurement of the first and second total current outputted at the first and the second output
Data Source
Figure 1~4
Figure 5~8
Figure 9
AI summary
Electrosurgical generator provides a HF alternating voltage to electrosurgical instruments, comprising a first/second HF generation unit (4, 4') supplying a first/second HF alternating voltage having a first/second frequency to a first/second output (16, 16') which are configured for connection of a first/second electrosurgical instrument (19, 19'). Upon activation a first current flows to the first electrosurgical instrument and simultaneously a second current flows to the second electrosurgical instrument. That portion of these currents being actually delivered from the electrosurgical instruments to the tissue to be worked on are working currents (Iw1, Iw2). They are important for safe operation but cannot be measured directly. The invention provides an observer unit (6) configured for indirect determination of said working currents (Iw1, Iw2) based on measured values of the total currents. The so determined working currents are used as input signals for an inverter controller (3), achieving improved control of the electrosurgical generator.