Brushless Motor Lead-Angle Setting Method for Noise Reduction
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Solution Overview
Problem
Conventional brushless motor control systems face challenges in accurately detecting the minimum motor current value due to noise susceptibility and frequent changes in phase correction, leading to inefficient rotational control and increased noise.
Innovation Solution
A method for setting a lead-angle value by rotating the rotor at a given rpm, switching the lead-angle value, calculating average current values, and determining the smallest total value to set the lead-angle value that minimizes motor current, thereby improving accuracy and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the motor control circuit detects minimum motor current value by frequent phase correction, then the rotational control accuracy is improved, but the noise susceptibility increases and measurement accuracy deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the relationship between lead-angle values and motor current values in a lookup table before actual motor operation. During runtime, the control circuit simply queries this pre-computed table rather than performing real-time detection and correction, thereby avoiding noise susceptibility while maintaining measurement accuracy.
2Use of energy by moving object
If the lead-angle value is frequently adjusted to minimize motor current, then the rotational efficiency is improved, but the system stability deteriorates due to frequent changes
Solution Approach 1:
The patent pre-computes the optimal lead-angle values for different operating conditions and stores them in advance. During motor operation, the control circuit selects from these pre-determined values based on current operating parameters, avoiding frequent adjustments and maintaining system stability while still achieving optimal rotational efficiency.
Solution Approach 2:
The patent implements a dynamic lookup table that provides different lead-angle values based on varying operating conditions such as speed and load. The system dynamically selects the appropriate pre-computed lead-angle value from the table rather than using a fixed value or frequently adjusting the lead-angle, thereby maintaining both efficiency and stability.
3Measurement precision
If the position sensor is aligned with the given position, then the rotational control accuracy is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent changes the approach from physical alignment to parameter-based correction. Instead of requiring precise physical alignment of the position sensor during manufacturing, the system measures the actual alignment error and compensates for it by adjusting the lead-angle parameter. This transforms a manufacturing precision problem into a controllable parameter adjustment problem.
Data Source
AI summary
A method for setting a lead-angle value of a motor drive control circuit is disclosed. The motor drive control circuit energizes and drives the windings of a motor with an energizing timing based on a stored lead-angle value. The method includes the steps of: rotating a rotor at a given rpm (step S102), energizing and driving the windings during the rotation at the given rpm with the lead-angle value being switched (step S110); calculating an average value of current amount that energizes and drives the windings (step S114); calculating a total value of consecutive multiple average values for each lead-angle value (step S120); finding a smallest total value among the total values, and setting a lead-angle value corresponding to the smallest total value as a stored lead-angle value (step S122).