BLDC Motor Overload Detection via Angle Difference
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Solution Overview
Problem
Existing methods for detecting overload and stalling in brushless direct current (BLDC) motors, especially those using sensorless vector control, face challenges in accurately determining motor stalling without increasing device costs and continuously flowing current, making it difficult to detect stalling conditions effectively.
Innovation Solution
An apparatus and method that measure the difference between electrical and mechanical angles of the BLDC motor using a regulator angle without a separate rotor position detection sensor, determining motor stalling by counting errors and controlling the motor velocity to 0 when the difference exceeds a predetermined threshold, allowing for accurate overload detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a position detection sensor device (hall sensor, encoder) is used to detect rotor position, then the accuracy of motor control is improved, but the device cost is increased
Solution Approach 1:
The patent extracts the rotor position detection function from separate sensor devices and implements it through sensorless vector control using only the existing three-phase current sensors. By measuring back-EMF voltages and calculating rotor position through software algorithms rather than hardware sensors, the solution eliminates additional cost while maintaining detection accuracy.
Solution Approach 2:
The system uses its own three-phase current sensing capability to simultaneously perform both motor control and rotor position detection functions. The current sensors serve dual purposes: controlling motor operation and detecting rotor position through back-EMF analysis, eliminating the need for separate position detection sensors.
2Device complexity
If sensorless vector control is used to reduce device cost, then the device complexity is reduced, but the ability to accurately detect stalling is worsened because current continues to flow during stalling
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors the difference between electrical angle (from back-EMF measurement) and mechanical angle (from current-based estimation). When the motor stalls, this angle difference deviates from the normal 90-degree relationship, providing a clear feedback signal for stalling detection even though current continues to flow.
Solution Approach 2:
The patent detects stalling by monitoring changes in the angle difference parameter between electrical and mechanical angles. During normal operation, this difference remains at 90 degrees, but during stalling, the parameter changes significantly, providing a reliable detection criterion without requiring additional sensors or interrupting current flow.
3Measurement precision
If the difference between electrical angle and mechanical angle is continuously monitored to detect stalling, then the stalling detection accuracy is improved, but the processing complexity is increased
Solution Approach 1:
The patent monitors the angle difference parameter continuously but only triggers stalling detection when the difference exceeds a predetermined threshold. This partial monitoring approach focuses computational resources on the critical detection moment rather than processing all angle data equally, reducing overall processing complexity while maintaining detection accuracy.
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
Enables accurate detection of motor stalling and overload conditions without additional sensors, reducing costs and improving stalling detection accuracy by controlling the motor velocity to prevent further damage.
Implementation Method 1
a sensorless method using a back electro motive force (BEMF) method
Implementation Method 2
a mechanical angle of the BLDC motor, estimated through current supplied to the BLDC motor
Data Source
AI summary
The present disclosure provides a brushless direct current (BLDC) motor overload detection apparatus. The BLDC motor overload detection apparatus includes a measurer for measuring an electrical angle of the BLDC motor, a determiner for determining whether a difference between the electrical angle measured by the measurer and a mechanical angle of the BLDC motor, estimated through current supplied to the BLDC motor, is within a predetermined range, and a driving controller for control of driving of the BLDC motor according to whether the BLDC motor stalls, determined by the determiner.