Brushless Motor Speed Estimation via Virtual Hall Signal
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Solution Overview
Problem
The use of Hall sensors in three-phase brushless direct current motors increases cost and reduces reliability, and is sensitive to temperature, limiting motor operation.
Innovation Solution
A method for estimating rotational speed by acquiring voltages of three terminals, calculating equivalent line voltage, determining a virtual Hall signal from zero-crossing points, and estimating motor speed without the need for physical Hall sensors, thereby simplifying the estimation process and reducing hardware complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If Hall sensors are added to generate commutation signals and provide motor position and rotational speed estimation, then the motor control function is improved, but the cost increases and reliability decreases
Solution Approach 1:
The patent extracts the speed estimation function from the Hall sensor system by using back electromotive force (BEMF) signals instead. The BEMF zero-crossing detection method eliminates the need for Hall sensors while maintaining the motor control function, thereby improving reliability without sacrificing ease of operation
Solution Approach 2:
The patent creates a virtual Hall signal by processing BEMF signals through coordinate transformation and zero-crossing detection. This virtual signal copy replaces the physical Hall sensor output, providing the same commutation information without the reliability issues of Hall sensors
2Ease of operation
If Hall sensors are used for position sensing and speed estimation, then motor control is enabled, but temperature sensitivity increases limiting motor operation
Solution Approach 1:
The patent replaces the Hall sensor-based magnetic field detection system with an electrical signal processing system that measures BEMF voltages. This substitution eliminates the temperature-sensitive Hall effect sensors while maintaining motor control capability through electrical measurement and computation
3Measurement precision
If virtual Hall signal is determined from equivalent line voltage zero-crossing points, then speed estimation accuracy is improved, but calculation complexity increases
Solution Approach 1:
The patent changes the reference parameter from phase voltages to equivalent line voltages for zero-crossing detection. This parameter transformation simplifies the calculation by eliminating the need for virtual neutral point construction and complex coordinate transformations, reducing computational complexity while maintaining speed estimation accuracy
Data Source
AI summary
The present application provides a method for speed estimation, device, electronic device, and storage medium, and relates to the technical field of rotational speed estimation. The method for speed estimation is applied to a three-phase brushless motor: firstly, acquire voltages of three terminals of a three-phase brushless motor; secondly, take the voltage difference value of each two terminals as an equivalent line voltage; thirdly, determine a virtual Hall signal according to a zero-crossing point of the equivalent line voltage; and lastly, estimate the rotational speed of the three-phase brushless motor according to the virtual Hall signal. The method for speed estimation, device, electronic device, and storage medium provided in the present application have the advantage of being simpler for rotational speed estimation.