Inverter Insulation Monitoring via Ground Current Trend Analysis
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Solution Overview
Problem
In large-scale motor driving systems where multiple inverters receive power from a common converter, existing methods are inefficient for monitoring insulation deterioration across numerous motors, requiring significant time and labor, and lack preventive maintenance capabilities for preventing abnormality occurrences due to insulation degradation.
Innovation Solution
An insulation deterioration monitoring apparatus and method that utilizes a computer with installed software to measure and analyze ground current values across multiple inverter units, generating direct current voltage in one stopped inverter unit to identify insulation issues, record data, and analyze trends for efficient monitoring and early detection of abnormalities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If insulation resistance measurement is performed by disconnecting the inverter and motor connection for each motor, then measurement accuracy is improved, but inspection time and labor increase significantly
Solution Approach 1:
The patent segments the inspection process by performing measurements sequentially for each inverter unit while the system is operational. The computer control unit systematically selects each inverter unit, generates DC voltage, and measures ground current in sequence, allowing insulation monitoring without complete system shutdown and reducing overall inspection time while maintaining measurement accuracy for each segment.
Solution Approach 2:
The patent applies preliminary action by generating DC voltage in the selected inverter unit before performing the ground current measurement. This preparatory step ensures that the measurement conditions are properly established, allowing accurate insulation resistance detection without requiring physical disconnection of the motor connection, thus saving time while maintaining measurement precision.
2Productivity
If ground current measurement is performed in a system with multiple inverters from a common converter, then inspection efficiency is improved, but the ability to detect specific inverter unit issues deteriorates
Solution Approach 1:
The patent segments the ground current measurement process by isolating each inverter unit through computer-controlled selection. The control unit activates DC voltage generation in one selected inverter unit at a time and measures its ground current separately, enabling efficient monitoring of multiple inverters while maintaining the precision to detect ground faults in specific units through systematic sequential measurement.
Solution Approach 2:
The patent implements feedback by using the computer control unit to systematically select each inverter unit, generate DC voltage, measure ground current, and record the results in association with the specific inverter unit. This closed-loop process ensures that measurement data from multiple inverters is properly attributed and analyzed, maintaining detection accuracy while improving overall inspection efficiency through automated sequential measurement.
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
Enables efficient monitoring of insulation deterioration for each inverter unit, reducing downtime and allowing for proactive handling of potential ground faults that could disrupt plant operations, thereby ensuring stable operation of large-scale plants.
Implementation Method 1
causes a corresponding motor driving inverter corresponding to the selected inverter unit to generate a direct current voltage
Implementation Method 2
a ground current measuring instrument for measuring ground current flowing between an output terminal of the converter and the ground
Data Source
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AI summary
The insulation deterioration monitoring apparatus comprises a computer on which software is installed. The software causes the computer to execute at least first to fourth processes. In the first process, during stopping of at least one inverter unit, the computer selects one inverter unit out of the stopped inverter units and causes the inverter corresponding to the selected inverter unit to generate a direct current voltage. In the second process, the computer measures the current value of the ground current while the corresponding motor driving inverter generates the direct current voltage. In the third process, the computer records the measured current value of the ground current for each inverter unit in association with the selected inverter unit. Then, in the fourth process, based on the measured current value of the ground current recorded for each inverter unit, the computer analyzes the tendency of insulation deterioration of each inverter unit.