Direct Drive Motor Magnetic Pole Position Correction
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Solution Overview
Problem
Direct drive motors experience significant torque reduction due to mounting errors between the motor and position detector, which can lead to uncontrollable positioning and potential collisions, especially when using multi-polar structures and limited movable ranges.
Innovation Solution
A motor magnetic pole position correction method that involves preventing the movable element's movement with a mechanical brake, inputting a position command different from the current position, detecting torque command values, determining and storing a magnetic pole position correction value, and performing motor control using an electrical angle offset to correct the positional relationship between the motor and position detector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a multi-polar structure is used to improve positioning accuracy, then positioning accuracy is improved, but torque reduction due to mounting errors increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the magnetic pole position correction value based on detected torque command values. When mounting errors cause torque reduction, the system modifies the electrical angle offset to compensate, thereby maintaining reliable torque output while preserving the high positioning accuracy enabled by the multi-polar structure.
Solution Approach 2:
The patent implements feedback by continuously monitoring torque command values and using this information to adjust the magnetic pole position correction value. The system compares detected torque with expected values and automatically corrects positional deviations between the motor and position detector, ensuring torque stability without sacrificing positioning precision.
2Reliability
If mechanical brake is applied to prevent movement during correction, then positioning control safety is improved, but movement capability is reduced
Solution Approach 1:
The patent applies preliminary action by engaging the mechanical brake before performing magnetic pole position correction. This ensures the movable element is securely held in place during the correction process, preventing unintended movements that could compromise safety. After correction is complete, the brake is released to restore full movement capability for normal operation.
3Power
If magnetic pole position correction is performed to correct mounting errors, then output torque is maintained, but system complexity increases
Solution Approach 1:
The patent applies self-service by implementing an automatic magnetic pole position correction function that operates autonomously within the existing control system. The correction value is automatically adjusted based on torque command value detection, eliminating the need for manual calibration or external intervention while maintaining output torque. This self-correcting mechanism adds minimal complexity compared to manual adjustment methods.
Data Source
AI summary
A motor magnetic pole position correction method includes preventing a movement of a movable element of a direct drive motor by mechanical brake (step S9), generating a command that designates a position spaced or separated from the present position (step S10), detecting a torque command value of the direct drive motor (step S12), determining a magnetic pole position correction value based on a comparison between the detected torque command value and a predetermined threshold value (steps S14 and S16), storing the determined magnetic pole position correction value in a memory (step S18), and performing motor control using an electrical angle offset value obtained based on the magnetic pole position correction value stored in the memory.