Sensorless BLDC Motor Control via Back-EMF Detection and Parameter Database
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Solution Overview
Problem
The challenge lies in managing the diverse types of sensorless BLDC motors used in ceiling fans, as existing control devices require specific matching parameters, leading to increased complexity and management issues for manufacturers due to variations in back-EMF constants, rated speeds, and pole pair numbers.
Innovation Solution
A control device comprising a detector circuit, driver circuit, and control circuit with a database of control parameter sets, which detects resistance, inductance, and back-EMF to generate a driver control signal, allowing for the selection of appropriate control parameters for different types of sensorless BLDC motors, thereby simplifying component preparation and management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Hall sensors are used to directly measure the position of the rotor, then the position measurement precision is improved, but the device complexity increases due to additional routing and the reliability deteriorates when sensors become dusty or exposed to high humidity
Solution Approach 1:
The patent extracts the position measurement function from physical Hall sensors and implements it through sensorless back-EMF detection. The controller infers rotor position by detecting the back-EMF voltage generated by the motor windings, eliminating the need for Hall sensors and their associated routing while maintaining position measurement capability
Solution Approach 2:
The patent uses back-EMF voltage as an intermediary to indirectly measure rotor position. Instead of directly sensing position with Hall sensors, the system measures the back-EMF voltage generated by the motor's electromagnetic induction, which contains position information that can be extracted through signal processing
2Manufacturing precision
If different control devices are prepared for different types of sensorless BLDC motors, then the control precision for each motor type is improved, but the manufacturing complexity and management burden increase significantly
Solution Approach 1:
The patent designs a universal controller that can adapt to different types of sensorless BLDC motors. The controller includes a database storing control parameters for multiple motor types and automatically selects the appropriate parameters based on motor identification, enabling one controller to serve multiple motor types without requiring separate specialized controllers for each motor variant
Solution Approach 2:
The patent implements dynamic parameter adjustment by storing multiple sets of control parameters (such as back-EMF constants, rated speeds, pole pair numbers) in a database and automatically selecting the appropriate parameter set based on the detected motor type. This allows the controller to adapt its operating parameters to match different motor characteristics
3Adaptability or versatility
If a database containing multiple control parameter sets is stored in the control circuit, then the adaptability to different motor types is improved, but the device complexity increases
Solution Approach 1:
The patent pre-stores multiple control parameter sets in the controller's database before actual operation. This preliminary preparation allows the controller to quickly identify and select the appropriate parameters when a motor is connected, eliminating the need for complex real-time parameter calculation or manual configuration during operation
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
This solution enables efficient control of various sensorless BLDC motors by automating the detection and selection of control parameters, reducing the need for multiple control devices and enhancing management efficiency, while also allowing for updates to accommodate new motor types, thus extending the device's market lifespan.
Implementation Method 1
Another design measures a back-electromotive force (back-EMF) to infer the position of the rotor and is sensorless
Data Source
AI summary
A control method is to be implemented by a control device, and includes: (A) storing a database that contains control parameter sets which respectively correspond to different types of sensorless BLDC motors; (B) detecting a resistance and an inductance of a sensorless BLDC motor of a ceiling fan, and searching the database, based on at least the detected resistance and the detected inductance, for one of the control parameter sets that corresponds to the sensorless BLDC motor of the ceiling fan; (C) detecting a back-EMF of the sensorless BLDC motor of the ceiling fan; and (D) generating a driver control signal based on said one of the control parameter sets and the detected back-EMF to drive the sensorless BLDC motor of the ceiling fan.