Three-Phase AC Motor Diagnosis With Low-Rotation Phase Sequencing
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Solution Overview
Problem
When diagnosing a three-phase alternating current motor, applying current to only two phase windings can cause significant rotation, leading to user discomfort due to the inability to perform vector control, which is necessary for precise resistance detection.
Innovation Solution
A diagnostic method that applies predetermined voltage in a specific order across three current paths, including a current path with the highest rate of change of generated torque with respect to rotation angle, to minimize motor rotation during resistance detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If current is applied to only two phase windings for resistance detection, then resistance value calculation is simplified, but the motor rotates significantly causing user discomfort
Solution Approach 1:
The patent applies dynamic control by sequentially energizing different phase combinations in a specific order rather than applying current statically to only two phases. The controller dynamically switches between different current paths (UV, VW, WU phases) to maintain motor stability while performing resistance detection, preventing significant rotation and user discomfort.
2Productivity
If current is applied to two phase windings for resistance detection, then measurement process is simplified, but motor stability deteriorates
Solution Approach 1:
The patent employs periodic action by sequentially applying current to different phase combinations (UV phase, then VW phase, then WU phase) in a predetermined order. This periodic energization of different phase pairs allows resistance detection while maintaining motor stability, as each phase combination is applied for a limited duration before switching to the next combination.
3Loss of time
If current is applied to two phase windings, then diagnostic time is reduced, but motor rotation increases causing discomfort
Solution Approach 1:
The patent changes the parameter of current application by transitioning from applying current to only two phases simultaneously to sequentially applying current to different phase combinations (UV, VW, WU) in a predetermined order. This parameter change allows resistance detection to be performed efficiently while controlling motor rotation through the specific sequencing and timing of current application to different phases.
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 effectively suppresses motor rotation during diagnosis, allowing for accurate resistance value calculation and abnormality detection in the motor windings while reducing the integral value of generated torque, thereby enhancing user comfort and diagnostic precision.
Implementation Method 1
a current path in which the current flows from the first phase winding to the second phase winding via a neutral point, a current path in which the current flows from the second phase winding to the third phase winding via a neutral point, and a current path in which the current flows from the third phase winding to the first phase winding via a neutral point
Data Source
AI summary
A diagnostic method of a three-phase AC motor including: applying predetermined voltage in an order of first, second, and third current paths among three current paths in which current flows from a first phase winding to a second phase winding, from the second phase winding to a third phase winding, from the third phase winding to the first phase winding, respectively, via a neutral point; and detecting an abnormality based on current values flowing in these paths, wherein the second current path is a path in which a rate of change of generated torque to change of the rotation angle at a current rotation angle of the motor is greatest among the three paths, and a rotation direction of the motor when the first current path is energized is a direction in which an absolute value of torque generated when starting energization of the second current path decreases.