Electrical Safety Circuit Using Delayed MOSFET Ground Switching
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Solution Overview
Problem
Conventional RCCs and RCCs are based on galvanic isolation, which is slow to react and can allow currents to reach dangerous levels for humans, and are costly to implement for rapid reaction.
Innovation Solution
An electrical circuit with a current delay circuit and two switching devices that operate in different modes to prevent dangerous currents without galvanic isolation, using a current delay circuit to control switching devices based on threshold currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If galvanic isolation is used in conventional RCCBs and RCDs, then electrical safety is provided, but the reaction time is slow and currents can reach dangerous levels
Solution Approach 1:
The patent replaces the mechanical galvanic isolation system with an electronic switching system using MOSFETs (Q1, Q2) and control circuits. This electronic substitution enables much faster reaction times (microseconds) compared to conventional mechanical RCCBs, while maintaining electrical safety through controlled switching and current limiting mechanisms.
Solution Approach 2:
The patent changes the operational parameters by using active electronic components with controllable resistance and switching characteristics. The MOSFETs can rapidly change their conductivity state, and the control circuit adjusts operating parameters (voltage, current, timing) to achieve fast protection response, transforming the static parameter approach of galvanic isolation into a dynamic parameter control system.
2Reliability
If galvanic isolation is implemented for rapid reaction, then safety improves, but the cost increases significantly
Solution Approach 1:
The patent employs relatively inexpensive electronic components (MOSFETs, resistors, capacitors, operational amplifiers) that can be mass-produced using standard PCB fabrication techniques. These components are replaceable and can be manufactured at low cost compared to specialized galvanic isolation devices, making the protection system economically viable for widespread implementation.
Solution Approach 2:
The electronic circuit design uses standard, multi-purpose components that can serve multiple functions within the circuit (e.g., resistors for both current limiting and biasing, capacitors for timing and filtering). This universality reduces the total component count and manufacturing complexity, thereby lowering production costs while maintaining safety functionality.
3Use of energy by moving object
If the first switching device remains conductive continuously, then power delivery to load is maintained, but dangerous current levels can occur
Solution Approach 1:
The patent implements feedback control through the control circuit that continuously monitors the state of the switching devices and load conditions. The control circuit adjusts the switching timing and duration based on feedback signals, ensuring that power delivery is maintained when safe while automatically interrupting conduction when current approaches dangerous levels, thus resolving the contradiction between continuous power delivery and current safety.
Solution Approach 2:
The patent employs periodic switching action where the first switching device (Q1) is turned on and off in controlled cycles. During the ON period, power is delivered to the load; during the OFF period, the circuit resets and prepares for the next cycle. This periodic operation allows sustained power delivery over time while preventing continuous current flow that could reach dangerous levels, achieving both objectives through time-based control.
Data Source
AI summary
The invention relates to an electrical circuit for electrical safety. The electrical circuit comprises an input configured to be connected to a power supply; an output configured to be connected to a load; a current delay circuit and a first switching device connected in series between the input and the output; and a second switching device connected between the first switching device and a ground. The electrical circuit is configured to operate in: a first mode in which the first switching device is in its conductive state thereby feeding a first current to the load and the second switching device is in its non-conductive state; a second mode, following the first mode, in which the first switching device is in its conductive state thereby feeding a first current to the load and the second switching device is in its conductive state thereby feeding a second current to the ground; and a third mode, following the second mode, in which the first switching device is in its non-conductive state and the second switching device is in its conductive state. The invention also relates to a system and a corresponding method.