Digital GFCI Microcontroller Miswire Detection
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Solution Overview
Problem
Existing ground fault circuit interrupter (GFCI) receptacles face challenges with repeatable miswire detection and calibration due to their analog circuit solutions, which are inflexible, prone to noise, and difficult to monitor, especially after initial installation.
Innovation Solution
A digital GFCI circuit with a microcontroller unit and integrated circuit that includes a self-test feature, trip signal generation, and a test mode to prevent unintended tripping, allowing for flexible control and monitoring of the main switch, enabling repeatable miswire detection and improved reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If analog circuit solutions are used for miswire detection, then the circuit can detect faults during initial installation, but the detection cannot be repeated after reinstallation and the circuit is difficult to calibrate
Solution Approach 1:
The patent replaces analog circuit solutions with a digital controller that uses software-based detection algorithms. The controller sequentially activates hot and neutral lines, measures voltage differentials, and determines miswire conditions through digital processing, enabling repeatable detection after reinstallation while improving calibration consistency
Solution Approach 2:
The patent changes the detection approach from passive analog monitoring to active digital measurement by controlling the state of switches (open/closed positions) and measuring voltage parameters under different switch states. This allows the system to adapt to different installation configurations and perform repeated detections
2Reliability
If analog circuits are used for GFCI operation, then the circuit can monitor current flow, but the circuit is susceptible to noise and environmental interferences
Solution Approach 1:
The patent replaces analog signal processing with digital signal processing. The controller samples voltage and current signals, applies digital filtering and analysis algorithms, and makes decisions based on processed digital data, thereby rejecting noise and environmental interferences that plague analog circuits
3Reliability
If a self-test circuit is added to create test faults, then the system can verify its operation, but the test may cause unintended tripping of the main switch
Solution Approach 1:
The patent disables the main switch tripping mechanism before executing the self-test fault injection. By预先 disabling the tripping capability, the system can safely create test faults without risking unintended circuit interruption, then re-enable tripping after the test completes
Solution Approach 2:
The patent introduces a control state mechanism that mediates between the self-test fault injection and the main switch tripping function. The controller manages the interaction by temporarily suppressing the tripping response during self-test operations, allowing fault detection without unintended consequences
Data Source
AI summary
A GFCI circuit that includes an electronically controllable main switch that can turn on, and turn off, the delivery of electrical power from the GFCI circuit. The main switch is controlled and monitored by a microcontroller unit using at least digital input and digital output signals, and which includes analog to digital converter. The microcontroller unit may also use the on-off functionality of the main switch in connection with repeatable detection of miswiring of the GFCI circuit. The GFCI circuit can further be adapted to conduct a self-test that can temporarily disable the ability of a trip signal generated by a GFCI integrated circuit in response to a test fault to cause the tripping of the main switch. The microcontroller unit further monitors one or more characteristics of the GFCI circuit, including the main switch and trip signal(s), and can determine whether the GFCI circuit has reached its end-of-life stage.