Motor Control Device Hall Timing Correction
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Solution Overview
Problem
Existing motor control devices for brushless motors face challenges in accurately suppressing vibration and abnormal noise due to variations in magnetization and sensor mounting, leading to potential motor misalignment and operational issues.
Innovation Solution
A motor control device with a switching control unit that corrects position detection signals for each Hall edge and adjusts the conducting pattern based on these corrections, using a correction factor calculated from detection errors to maintain optimal Hall stage timing and prevent abnormal noise generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If correction is performed at low speed at start of movement, then Hall stage timing accuracy is improved, but Hall pattern overtaking occurs causing control abnormalities
Solution Approach 1:
The correction application is made dynamic by conditionally enabling it based on motor speed and acceleration state. At low speeds where overtaking risk exists, correction is suppressed. At normal operating speeds, correction is actively applied to maintain timing accuracy. This dynamic switching resolves the contradiction by adapting the correction strategy to operational conditions.
Solution Approach 2:
The system changes the parameter of correction application based on speed and acceleration thresholds. By monitoring these parameters and adjusting whether correction is applied, the system avoids Hall pattern overtaking at low speeds while maintaining timing accuracy at normal speeds, thus resolving the contradiction between precision and reliability.
2Reliability
If correction is suspended upon detecting Hall pattern abnormality, then control stability is improved, but motor operation fails at high loads requiring continuous correction
Solution Approach 1:
The correction suspension strategy is made dynamic by evaluating multiple conditions including acceleration state and consecutive abnormality counts. Correction is only suspended when both acceleration is below threshold and abnormalities exceed a count threshold, allowing continuous correction during high-load operations while maintaining stability during genuine faults. This resolves the contradiction between stability and productivity.
Solution Approach 2:
The system changes the correction suspension decision based on multiple parameters including acceleration threshold, abnormality count threshold, and consecutive abnormality detection. By adjusting these parameters, the system allows correction to continue during high-load operations while suspending it during actual faults, thus resolving the contradiction between control stability and high load operation capability.
3Measurement precision
If correction is continuously applied without abnormality determination, then Hall stage timing accuracy is maintained, but motor lock detection becomes impossible
Solution Approach 1:
The system dynamically switches between correction application and abnormality determination modes. During normal operation, correction is applied to maintain timing accuracy. When abnormalities are detected, the system transitions to determination mode to identify motor lock or other faults. This dynamic switching resolves the contradiction between maintaining accuracy and detecting abnormalities.
Solution Approach 2:
The system maintains continuous monitoring and correction capability while periodically performing abnormality determination. Rather than completely suspending correction during determination, the system continues useful correction actions while adding diagnostic functionality, thus maintaining both timing accuracy and abnormality detection capability simultaneously.
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 solution effectively suppresses vibration and abnormal noise by ensuring accurate Hall stage timing, allowing for continuous correction even during abnormality determination and maintaining motor operation at high loads.
Implementation Method 1
three Hall sensors that detect a rotation position are attached at an interval of 120° in the rotation direction so that switching of magnetic poles of the sensor magnet can be detected
Data Source
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AI summary
A motor control device includes: a switching control unit that acquires a next Hall pattern from a predetermined Hall pattern among six Hall patterns being combinations of potentials of position detection signals that are outputs of a plurality of sensors, determines whether the next Hall pattern is different from a first Hall pattern scheduled next to the predetermined Hall pattern, and counts a number of times the next Hall pattern is different from the first Hall pattern, in which correction is suspended when the number of times the next Hall pattern is different from the first Hall pattern is greater than a predetermined number of times of abnormality, or when a rotation speed of a rotor is not being accelerated even if the number of times the next Hall pattern is different from the first Hall pattern is less than or equal to the predetermined number of times of abnormality.