Ground Fault Detection Circuit Using Virtual Ground Sensing
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Solution Overview
Problem
Existing electrical systems face challenges in accurately monitoring and continuously detecting ground connection faults, particularly in equipment with loose or intermittent connections, which can lead to safety hazards and inefficiencies.
Innovation Solution
A system comprising a chassis ground, virtual ground, rectifier, instrumentation amplifier, and controller is used to monitor the ground connection by amplifying differential voltages and currents, rejecting common mode noise, and detecting anomalies, allowing for real-time fault detection and power deactivation when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional ground connection monitoring is used, then the system is simple, but the detection accuracy is insufficient for loose or intermittent faults
Solution Approach 1:
The patent introduces a virtual ground as an intermediary reference point that is electrically isolated from the chassis ground through a current sensor. This virtual ground serves as a stable reference for detecting ground faults without being affected by the same interference as the chassis ground, thereby improving detection accuracy while maintaining manageable system complexity through modular design
Solution Approach 2:
The patent replaces traditional mechanical or simple electrical ground monitoring with an electronic measurement system using operational amplifiers, instrumentation amplifiers, and microcontrollers. This substitution enables precise detection of voltage differences and current leakage, significantly improving fault detection capability while the modular electronic architecture keeps the overall system complexity controlled
2Reliability
If continuous monitoring is implemented, then real-time fault detection is achieved, but energy consumption increases
Solution Approach 1:
The patent implements periodic sampling of ground voltage and current parameters by the microcontroller rather than continuous full-power monitoring. The system periodically reads analog-to-digital converter values and processes them to detect ground faults, achieving continuous monitoring capability while reducing average energy consumption through time-multiplexed operation
Solution Approach 2:
The monitoring system uses the existing ground connection and power supply infrastructure of the electrical equipment to perform self-diagnosis. The ground fault detection circuit draws minimal power from the equipment's existing power system, and the microcontroller processes data using the equipment's existing processing resources, thereby achieving continuous monitoring with minimal additional energy consumption
3Measurement precision
If differential voltage amplification is used, then common mode noise is rejected, but the circuit complexity increases
Solution Approach 1:
The patent uses the virtual ground as an intermediary reference that is electrically isolated from the chassis ground through a current sensor. This intermediary reference point allows the instrumentation amplifier to measure differential voltages without being affected by common-mode noise on the chassis ground, achieving high signal-to-noise ratio while the modular virtual ground implementation keeps circuit complexity manageable
Solution Approach 2:
The patent replaces complex passive RC filtering or transformer-based noise rejection circuits with active electronic instrumentation amplifiers and digital signal processing. The instrumentation amplifier provides high input impedance and differential amplification with built-in common-mode rejection, while the microcontroller performs digital filtering and analysis, achieving superior noise rejection with more compact and controllable circuitry
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
Enhances the accuracy and consistency of ground connection monitoring, reduces single-phase faults, and enables continuous, real-time detection of disconnections, ensuring safety and reliability of electrical equipment.
Implementation Method 1
a rectifier coupled to the chassis ground and configured to output a first voltage based on a virtual ground voltage and a chassis ground voltage
Implementation Method 2
an instrumentation amplifier coupled to the rectifier to receive the first voltage and a second voltage, the instrumentation amplifier configured to output a third voltage based on the first voltage and the second voltage
Data Source
AI summary
A system for monitoring a ground connection on electrical equipment is presented, the system including: a chassis ground; a virtual ground; a rectifier coupled to the chassis ground and configured to output a first voltage based on a virtual ground voltage and a chassis ground voltage; an instrumentation amplifier coupled to the rectifier to receive the first voltage and a second voltage, the instrumentation amplifier configured to output a third voltage based on the first voltage and a second voltage; and a controller coupled to the instrumentation amplifier. The controller is configured to receive the third voltage, determine whether the ground connection of the electrical equipment to the chassis ground is adequate based on the third voltage, and deactivate power to the electrical equipment responsive to determining that the ground connection is inadequate.