Manually guided device having high voltage power electronics
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Solution Overview
Problem
Hand-guided devices with high voltage power electronics in insulating housings can experience electrical discharges through the user's hand, especially when operating with AC voltage, leading to unpleasant sensations due to high current density.
Innovation Solution
The device incorporates an electrically conductive potential equalizing facility that forms part of the outer surface, isolated from the power electronics, to increase the surface area for electrical potential equalization, reducing current density and making discharges imperceptible to the user.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the housing is made electrically insulating to prevent energy transmission to the user's hand, then safety is improved, but electrical discharges and back discharges still occur via the hand during high voltage operation
Solution Approach 1:
The patent applies the equipotentiality principle by providing a conductive connection between the housing and the user's hand through the potential equalizing facility. This equalizes the electrical potential between the housing and the user, preventing potential differences that would cause discharge. The conductive path allows charges to redistribute evenly, eliminating the harmful discharge effect while maintaining the insulating housing structure.
Solution Approach 2:
The patent introduces a potential equalizing facility as an intermediary element between the high voltage power electronics and the user's hand. This intermediary provides a controlled conductive path that safely equalizes potential without allowing harmful discharges. The facility acts as a mediator that manages the electrical interaction between the insulating housing and the user's body.
2Ease of operation
If the outer surface is made electrically conductive to enlarge the potential equalizing surface, then current density is reduced and user comfort is improved, but the housing loses its electrical insulation property
Solution Approach 1:
The patent applies local quality by making only specific regions of the housing conductive rather than the entire housing. The potential equalizing facility is localized to the outer surface region that contacts the user's hand, while the rest of the housing maintains its insulating properties. This localized conductive treatment reduces current density at the contact point without compromising the overall electrical insulation of the housing structure.
Solution Approach 2:
The patent segments the housing into different functional zones: an insulating bulk structure for overall safety and a conductive outer surface layer for potential equalization. This segmentation allows the housing to simultaneously provide electrical insulation where needed and conductive properties at the user contact interface, resolving the contradiction between insulation and comfort.
3Power
If the power electronics are operated with high voltage and AC voltage to provide sufficient power for treatment, then treatment capability is improved, but the frequency and probability of discharges increase
Solution Approach 1:
The patent uses equipotentiality to address discharge frequency by continuously equalizing the electrical potential between the housing and the user's hand throughout the AC voltage cycle. This prevents the buildup of potential differences that would otherwise cause repeated discharges during high frequency AC operation, allowing full power operation without increased discharge frequency.
Solution Approach 2:
The patent converts the potentially harmful effect of high voltage operation into a beneficial one by using the electrical energy to create a controlled conductive path through the potential equalizing facility. Instead of allowing uncontrolled discharges, the system uses the high voltage to establish a safe equipotential condition, turning the harmful high voltage into a mechanism for preventing discharges.
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 design enhances user comfort by reducing the noticeability of discharges and allows for simpler, cost-effective production while maintaining unchanged power electronics and electrical voltage supply.
Implementation Method 1
the device has an electrically conductive potential equalizing facility (16) that at least in part forms an outer surface (17) of the device, which during use is in contact with the hand (4) of the user
Implementation Method 2
devices that generate plasma via a plasma source that is accommodated in the housing and is supplied electrically using the power electronics
Data Source
AI summary
A manually guided device has an electrically insulating housing in which power electronics operated by high voltage are accommodated. The device is used in particular for treating an object, in particular by way of plasma. Increased comfort and simplified manufacturing of the device result from an electrically conductive equipotential bonding device which is electrically isolated from the power electronics and which forms, at least in part, an outer surface of the device with which a user's hand is in contact during use.