Three-Phase Motor Winding Diagnosis With Rotation Suppression
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Solution Overview
Problem
When current is applied to only two phase windings of a three-phase alternating current motor, significant rotation occurs due to the inability to perform vector control, causing discomfort to the user.
Innovation Solution
A diagnostic method involving the application of predetermined voltage in specific current paths (first, second, and third current paths) to detect abnormalities in the motor windings while minimizing rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If current is applied to only two phase windings of three phase windings for resistance detection, then the diagnostic process can be simplified, but the motor may move significantly causing user discomfort
Solution Approach 1:
The patent applies preliminary anti-action by selecting a specific current path for resistance detection that generates torque in the opposite direction to counteract the motor's rotation. The controller determines the rotation direction based on the current rotation angle and selects a current path that produces counterbalancing torque, thereby suppressing unwanted motor movement during diagnosis while maintaining diagnostic simplicity.
2Measurement precision
If current is applied to two phase windings to calculate resistance values, then the measurement can be performed, but vector control is not possible leading to significant motor movement
Solution Approach 1:
The patent applies dynamics by making the current path selection dynamic based on the motor's current rotation angle. The controller continuously monitors the rotation angle and dynamically selects the appropriate current path from multiple options to apply current to two phase windings. This dynamic adaptation allows resistance measurement while simultaneously controlling motor stability by choosing paths that minimize rotation.
3Ease of operation
If current paths are selected based on rotation angle to suppress motor rotation, then user comfort is improved, but the control logic becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the optimal current path selections for different rotation angle ranges. The controller determines the current rotation angle and selects the appropriate current path based on pre-established criteria, avoiding the need for complex real-time calculations. This preliminary preparation simplifies the control logic while maintaining the ability to suppress motor rotation effectively.
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
The method effectively suppresses the rotation of the three-phase alternating current motor during diagnosis, allowing for accurate detection of abnormalities in the windings.
Implementation Method 1
A resistance value of each phase winding of a three-phase alternating current motor can be calculated by a current value and a voltage value between terminals when current for resistance detection is applied to any two of the three phase windings
Data Source
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Figure 2A~2C
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AI summary
A diagnostic method of a three-phase alternating current motor having a first phase winding, a second phase winding, and a third phase winding, including: applying predetermined voltage for a predetermined period of time in an order of a first current path, a second current path, and a third current path among three current paths of a current path in which current flows from the first phase winding to the second phase winding via a neutral point, a current path in which current flows from the second phase winding to the third phase winding via a neutral point, and a current path in which current flows from the third phase winding to the first phase winding via a neutral point; and detecting an abnormality in the first phase winding, the second phase winding, and the third phase winding based on current values flowing in the first current path, the second current path, and the third current path when the predetermined voltage is applied, wherein the second current path is a current path in which a rate of change of generated torque with respect to change of the rotation angle at a current rotation angle of the three-phase alternating current motor is greatest among the three current paths, and a rotation direction of the three-phase alternating current motor when the first current path is energized is a direction in which an absolute value of generated torque generated when starting energization of the second current path decreases.