Rotor Angle Correction for Synchronous Motors
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Solution Overview
Problem
Inaccuracies in the assembly of sensors for electrically commutated synchronous motors lead to incorrect rotor position measurements, resulting in electrical error angles, reduced torque, increased noise, and losses, especially in motors with a high number of poles, due to hysteresis effects and mechanical assembly errors.
Innovation Solution
A calibration method involving an externally imposed rotating field is used to record and store pairs of electrical and mechanical angles in both directions, allowing for the calculation and storage of a correction value to account for error angles, enabling precise rotor position control without additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical sensor adjustment or automated input of compensation value is used, then electrical error angle is reduced, but device complexity and manufacturing cost increase
Solution Approach 1:
The system performs self-calibration by automatically detecting the mechanical reference position and calculating the correction value without external intervention. The control unit autonomously executes the calibration procedure, eliminating the need for manual sensor adjustment mechanisms and reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The calibration method changes the operational parameters of the motor by imposing an externally generated rotating field at a specific frequency and amplitude. This allows the system to operate in a calibrated state during normal operation, enabling automatic detection and correction of angular position errors without additional hardware.
2Manufacturing precision
If manual sensor adjustment is performed, then assembly accuracy is improved, but productivity and ease of operation deteriorate
Solution Approach 1:
The system performs preliminary calibration actions by automatically detecting the mechanical reference position and calculating the correction value before normal operation begins. This preliminary automatic calibration eliminates the need for time-consuming manual adjustment procedures during assembly, thereby improving productivity while maintaining assembly accuracy.
Solution Approach 2:
The patent replaces manual mechanical adjustment procedures with an automated electronic calibration system. The control unit automatically executes the calibration sequence, substitutes human operators in the calibration process, and eliminates the need for manual sensor positioning, thereby significantly improving productivity and ease of operation.
3Measurement precision
If sensor assembly inaccuracies occur, then measurement precision deteriorates, but the invention provides automatic correction
Solution Approach 1:
The system implements feedback by continuously monitoring the electrical angle from the sensor and comparing it with the mechanical reference position. The calculated correction value is fed back to the control unit to compensate for assembly inaccuracies, thereby maintaining measurement precision and control accuracy despite initial sensor misalignment.
Solution Approach 2:
The calibration method exploits the asymmetry between the electrical angle measured by the sensor and the mechanical reference position to detect and correct assembly errors. By identifying the angular offset through the externally imposed rotating field and comparing phases, the system quantifies and compensates for the asymmetric misalignment, improving reliability.
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 method accurately detects and corrects electrical angle errors, ensuring precise motor control and minimizing noise and losses by averaging angle differences from both measurement directions, effectively compensating for phase errors and achieving zero phase error in rotor position control.
Implementation Method 1
the motor is controlled in a calibration run with an externally imposed rotating field
Data Source
AI summary
The invention relates to a method for ascertaining a correction value for the angle of the rotor of an electrically commuted reversible synchronous motor relative to a sensor used for the activation thereof. In order to equalize the sensor and recognize and correct electrical incorrect angles and incorrect controls, it is proposed that the motor be activated in a calibration journey using an externally forced rotating field, the electrical angle of the rotating field and the mechanical angle of the rotor, which is measured by the external sensor, be measured simultaneously on at least one reference position during the calibration journey and be stored associated with one another as a measurement series of value pairs, the electrical angle of the rotating field and the mechanical angle of the rotor, which is measured by the sensor, be detected simultaneously after direction reversal of the rotating field and be stored associated with one another as a second measurement series of value pairs, the angle difference between the electrical angle and the mechanical angle be calculated from value pairs of both measurement series which correspond to one another, and the correction value for taking the actual incorrect angle into consideration be calculated from the two angle differences by averaging and be stored.