Transformer Leakage Control Winding for Surgical Tool Current Cancellation
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Solution Overview
Problem
Current surgical tool systems face challenges in reducing leakage current, particularly in ultrasonic systems, due to high voltages exceeding the capacity of existing matched current sources, and difficulty in adjusting current flow to match parasitic currents, which can lead to unsafe levels of current flow through patients.
Innovation Solution
A control console with a transformer incorporating a self-contained matched current source, featuring a leakage control winding and capacitor, allows for precise adjustment of current levels and voltage settings, enabling effective cancellation of parasitic currents across high side conductors, even at high voltages, to minimize leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a matched current source is used to reduce leakage current, then leakage current is reduced, but the solution cannot handle high voltages exceeding 250VAC
Solution Approach 1:
The patent changes the voltage rating parameter of the capacitor from 250VAC to a higher voltage rating (e.g., 1000VAC or more) to enable the matched current source to handle high voltages in ultrasonic surgical systems while maintaining leakage current reduction functionality
Solution Approach 2:
The patent makes the matched current source adjustable by providing variable capacitance or variable inductance, allowing the cancellation current to be dynamically tuned to match the parasitic current at different operating voltages and frequencies, thereby maintaining effectiveness across varying voltage conditions
2Object-affected harmful factors
If a matched current source is used to reduce leakage current, then leakage current is reduced, but the current level cannot be adjusted to match parasitic current
Solution Approach 1:
The patent introduces adjustable elements (variable capacitors, variable inductors, or switchable capacitor/inductor combinations) that allow the matched current source parameters to be dynamically changed during system operation or setup, enabling precise matching of the cancellation current to the parasitic current at different operating conditions
Solution Approach 2:
The patent incorporates a feedback mechanism that monitors the actual leakage current or parasitic current and automatically adjusts the matched current source parameters to optimize cancellation, ensuring continuous effectiveness without manual intervention
3Object-affected harmful factors
If insulation is increased to reduce parasitic capacitance, then leakage current is reduced, but mechanical coupling and vibration transfer are dampened
Solution Approach 1:
The patent introduces a matched current source as an electrical intermediary that cancels parasitic current through active compensation, allowing the use of minimal insulation necessary for mechanical coupling while maintaining safety through electrical current cancellation rather than relying solely on increased physical insulation
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
The solution effectively reduces leakage current to safe levels, ensuring patient safety by precisely matching parasitic currents, thereby meeting stringent IEC 60601 standards for both general and cardiac tissue applications.
Implementation Method 1
a first winding (252) having a first voltage generated across the first winding by electromagnetic induction from an input signal
Implementation Method 2
a capacitor (248) having a current generated by the capacitor that is opposite in phase to the parasitic current
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Control console (50) for a powered surgical tool that includes a transformer (250) with a secondary winding (264) across which the tool drive signal is present. Also internal to the transformer is a matched current source that consists of a leakage control winding (246) and a capacitor (248). The current sourced by the matched current at least partially cancels out leakage current that may be present.