Rotation Angle Sensor Calibration via Two-Phase Coil Stopping
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Solution Overview
Problem
Existing calibration methods for rotation angle sensors in three-phase brushless electric motors face challenges in accurately stopping the motor rotor at a predetermined position, requiring external servo mechanisms and additional equipment, leading to inaccurate detection values and increased costs.
Innovation Solution
A calibration method that excites a single-phase or a pair of coils to rotate the motor shaft to specific stop positions, using two-phase energization to ensure accurate stopping, and generates sensor-error correction parameters based on reproducible detection values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all three-phase coils are excited to rotate the motor rotor, then the motor rotor can be rotated through a predetermined rotation angle, but the motor rotor cannot stop accurately at the desired predetermined rotation stop position
Solution Approach 1:
The patent segments the coil excitation process into two distinct phases: a first excitation phase that rotates the rotor to a preliminary position, and a second excitation phase that makes precise adjustments to achieve the exact predetermined stop position. This segmentation allows the system to overcome the limitation of using all three-phase coils simultaneously, which cannot achieve accurate stopping.
Solution Approach 2:
The patent applies preliminary action by first rotating the motor rotor to a preliminary rotation position using initial coil excitation, then performing a second excitation to adjust the rotor to the exact predetermined stop position. This two-stage approach ensures accurate positioning without requiring external servo mechanisms.
2Measurement precision
If an external servo mechanism is used to enable accurate stop at the predetermined rotation stop position, then accurate rotation angle error detection can be achieved, but extra expenditure for equipment is required
Solution Approach 1:
The patent implements self-service by enabling the motor rotor to perform its own calibration without requiring external servo mechanisms. The controller executes a calibration routine that uses the motor's existing coil structure to achieve accurate positioning, thereby eliminating the need for additional expensive equipment while maintaining high measurement precision.
Solution Approach 2:
The patent extracts the calibration function from external equipment and integrates it into the motor controller itself. By removing the dependency on external servo mechanisms and implementing the calibration routine within the existing controller, the system achieves accurate rotation angle error detection without adding device complexity.
3Ease of manufacture
If only inaccurate detection values are obtained due to inaccurate rotor stopping, then calibration cannot be performed accurately, but using all three-phase coils for rotation is the standard method
Solution Approach 1:
The patent applies dynamics by making the coil excitation pattern adaptive and variable. Instead of using a fixed excitation method with all three-phase coils, the system dynamically adjusts which coils are excited and in what sequence, based on the current rotor position and the target stop position. This dynamic approach enables both ease of manufacture and high detection value accuracy.
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 accurate and reproducible stopping of the motor rotor at predetermined positions, allowing for highly accurate correction of rotation angle errors without additional equipment, thereby improving detection precision.
Implementation Method 1
a stator coil including three-phase coils of a U phase, a V phase, and a W phase; a motor rotor to be rotated by excitation of the stator coil
Data Source
AI summary
A motor shaft is rotated to a predetermined rotation stop position by excitation of two-phase coils out of three-phase coils of a stator coil, and a detection value of a rotation angle sensor at the rotation stop position is acquired. Further, a sensor-error correction parameter for correcting a detection value of the rotation angle sensor in drive control of an electric motor is generated from the acquired detection value of the rotation angle sensor. With this configuration, in rotating a motor rotor to the predetermined rotation stop position, two coils out of the three-phase coils of the stator coil are excited. By sequentially changing the coils being excited, it is possible to cause the motor rotor to stop accurately at the predetermined rotation stop position.