Electric Power Circuit Isolation Fault Detection
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Solution Overview
Problem
Existing electric motor systems face challenges in accurately monitoring and detecting faults in electrical isolation between the power circuit and chassis ground, particularly due to degradation in insulation wire, which can reduce torque capacity and is difficult to assess with conventional methods.
Innovation Solution
A method is introduced that involves injecting a common voltage component into the common mode voltage of electrical phases during operation and monitoring negative-ground and positive-negative voltages to determine AC line resistance, allowing for real-time detection of faults in electrical isolation between the power circuit and chassis ground.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional monitoring methods are used, then the system structure remains simple, but the ability to detect insulation degradation and isolation faults is insufficient
Solution Approach 1:
The system uses the existing operational voltages and currents in the power circuit to detect isolation faults, rather than requiring separate test signals or additional test equipment. The control module leverages the natural operation of the motor driver circuitry to perform both motor control and insulation monitoring functions simultaneously.
Solution Approach 2:
The control module performs multiple functions: it controls the motor driver circuitry and simultaneously monitors insulation resistance and detects isolation faults. This multi-functionality eliminates the need for separate dedicated monitoring equipment, maintaining system simplicity while improving detection capability.
2Reliability
If insulation wire degradation is not detected, then the system operates continuously, but torque capacity reduces and motor performance degrades
Solution Approach 1:
The system continuously monitors insulation resistance during normal operation to detect degradation before it causes complete isolation failure or motor damage. By detecting issues early through ongoing measurement of isolation resistance, the system can take preventive action before torque capacity is significantly reduced.
Solution Approach 2:
The control module uses feedback from monitored voltages and currents to determine changes in isolation resistance. This feedback mechanism allows the system to track insulation degradation over time and alert operators before critical failures occur, maintaining both reliability and productivity.
3Difficulty of detecting and measuring
If additional hardware is added for fault detection, then detection capability improves, but system cost and complexity increase
Solution Approach 1:
The existing motor driver circuitry and control module perform both motor control and insulation monitoring functions. The system uses its own operational signals to measure isolation resistance, eliminating the need for separate test equipment or additional sensors.
Solution Approach 2:
The patent combines the motor control function and insulation monitoring function into a single control module. By merging these functions, the system achieves improved fault detection capability without adding separate hardware systems, thus avoiding increased complexity and cost.
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 approach enables effective detection and classification of AC line isolation faults, preventing motor degradation by identifying and addressing isolation issues in real-time without requiring additional hardware, thus maintaining motor performance and efficiency.
Implementation Method 1
An AC line resistance is determined based upon the negative-ground voltage and the positive-negative voltage. Faults in electrical isolation between the electric power circuit and a chassis ground are detected based upon the AC line resistance.
Data Source
AI summary
A method for monitoring an electric power circuit configured to transfer a power signal to a torque module that is electrically isolated from a chassis ground includes injecting a common voltage component into a common mode voltage of electrical phases during operation and monitoring a negative-ground voltage and a positive-negative voltage of the electric power circuit. An AC line resistance is determined based upon the negative-ground voltage and the positive-negative voltage. Faults in electrical isolation between the electric power circuit and a chassis ground are detected based upon the AC line resistance.