Brushless Motor Controller Low-Speed Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Brushless motors experience inefficiency, noise, and vibration during low-speed operation due to overflow in delay counters, which incorrectly set energizing timing, and existing solutions require complex computations increasing controller cost.
Innovation Solution
A brushless motor controller that switches between normal and advancing angle energizing timings based on rotor speed, using a control switching unit to adjust the energizing timing, preventing counter overflow and maintaining efficient operation at low speeds with simplified control logic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If angle advancing control is used to offset energizing timing delay at higher speeds, then motor efficiency is improved at medium-to-high speeds, but the delay counter overflows at extremely low speeds causing incorrect energizing timing
Solution Approach 1:
The patent applies dynamics by making the energizing timing control mode switchable between two states (angle advancing control and normal timing control) based on rotor speed. The control switching unit dynamically selects which control method to use, allowing the system to adapt its behavior to different operating conditions and avoid the counter overflow problem at low speeds while maintaining efficiency at higher speeds.
Solution Approach 2:
The patent changes the control parameter (energizing timing method) based on the rotor speed parameter. When rotor speed is below the threshold, the system switches from angle advancing control to normal timing control, effectively changing the operational parameter to prevent counter overflow and ensure accurate energizing timing at low speeds.
2Measurement precision
If complicated computations are performed to calculate optimum energizing timing for each rotation speed range, then energizing timing accuracy is improved, but controller cost increases due to higher CPU requirements
Solution Approach 1:
The patent segments the control approach into two distinct modes: angle advancing control for medium-to-high speeds and normal timing control for low speeds. This segmentation allows the system to use simple threshold-based switching logic instead of complex computations for every speed range, reducing CPU requirements while maintaining timing accuracy through the appropriate control method.
Solution Approach 2:
The patent uses a simple threshold value and basic control switching logic instead of expensive high-performance CPU computations. The solution replaces complex real-time calculations with a straightforward comparison operation and mode switching, significantly reducing controller cost while achieving the desired timing accuracy.
Data Source
AI summary
A brushless motor controller that controls a brushless motor by determining an energizing timing of a three-phase stator coil based on the rotational position and speed of a rotor. The controller includes a normal timing generation unit, an advancing timing generation unit, and a control switching unit. The normal timing generation unit generates a normal energizing timing. The advancing angle timing generation unit generates an advancing angle energizing timing advanced by a predetermined amount from the normal energizing timing and a final advancing angle energizing timing delayed by a delay amount from the advancing angle energizing timing. The control switching unit switches rotation control of the motor between a first rotation control executed in accordance with the normal energizing timing and a second rotation control executed in accordance with the final advancing angle energizing timing.