Motor Position Sensor Calibration Using PWM and Orthogonal Signals
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Solution Overview
Problem
Existing position sensor calibration methods for motors are prone to interference and inaccuracies, especially at longer distances and with increasing positional resolution, leading to potential step loss and poor real-time performance.
Innovation Solution
A method and device for calibrating a position sensor that utilizes an absolute lag angle based on PWM signal feedback to calibrate relative angles, incorporating an orthogonal signal and electrical angles to create a calibration mapping table for accurate position sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If SPI communication is used for position sensor, then communication distance can be extended, but position information becomes susceptible to interference
Solution Approach 1:
The patent introduces an intermediary calibration process that mediates between the position sensor and motor controller. A calibration mapping table is created by comparing sensor feedback with actual motor position, serving as a mediator to correct interference-induced errors in position information transmission
Solution Approach 2:
The patent implements feedback mechanisms where the position sensor continuously provides position information to the motor controller, and the calibration process uses feedback from both PWM signals and orthogonal signals to adjust and correct the mapping table, compensating for interference effects
2Length of stationary object
If PWM communication is used for position sensor, then communication distance can be extended, but communication lag increases significantly as positional resolution increases
Solution Approach 1:
The patent segments the position encoding into multiple bits (e.g., 10-bit resolution divided into segments), allowing parallel transmission of position information through orthogonal signals while using PWM for coarse position updates, thereby reducing overall communication lag while maintaining high resolution
3Speed
If orthogonal signal is used for position sensor, then communication speed is improved, but absolute position information feedback is not provided
Solution Approach 1:
The patent merges orthogonal signals (for high-speed communication) with PWM signals (for absolute position information) into a unified calibration system. The calibration mapping table integrates information from both signal types, combining the speed advantage of orthogonal signals with the absolute position capability of PWM
4Measurement precision
If sensor position calibration is performed in prior art, then position information can be obtained, but calibration is easily disturbed and position information becomes inaccurate
Solution Approach 1:
The patent performs calibration beforehand to create a mapping table that cushions against future disturbances. The calibration process accounts for potential interference and errors by pre-establishing correction factors in the mapping table, which are then applied during normal operation to maintain accuracy despite disturbances
Data Source
AI summary
The present invention relates to the technical field of position calibration, and in particular to a method and a device for calibrating a position sensor applied to a motor. The method comprises acquiring absolute position information of a motor based on feedback of a PWM signal; giving an orthogonal signal to the motor; giving an electrical angle in a first direction to the motor, and recording first relative angles fed back by the orthogonal signal; acquiring a first calibration mapping table for mapping the first relative angles to the electrical angle based on a mapping relation between the first relative angles and the electrical angle; and setting the first calibration mapping table as a mapping table after position sensor calibration to perform calibration; utilizing an absolute lag angle based on feedback of a PWM signal to calibrate relative angle with relatively better real-time performance, in order to avoid step loss.