Integrated BLDC Actuator With Absolute Magnetic Position Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Brushless DC electric motors lack high-resolution positional accuracy and complexity in motion control due to reliance on Hall-effect sensors and additional encoder hardware, which is costly and mechanically cumbersome, especially in small-scale applications like diagnostic systems and robotic devices.
Innovation Solution
Integration of an absolute encoder within the motor, utilizing dual magnetic rings and Hall-effect sensors to generate high-resolution positional data without additional hardware, enabling precise commutation and motion control through a microcontroller with ADC capabilities, allowing for wireless communication and synchronization of multiple motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Hall-effect sensors are used for commutation in BLDC motors, then motor operation is achieved, but positional accuracy and resolution are limited
Solution Approach 1:
The patent combines the motor function and encoder function into a single integrated actuator. The same permanent magnets on the rotor serve both to generate motor torque and to provide positional encoding signals, eliminating the need for separate encoder hardware and reducing system complexity while improving positional accuracy.
Solution Approach 2:
The permanent magnets on the rotor perform multiple functions: they generate the magnetic field for motor commutation and simultaneously provide the magnetic field variations needed for high-resolution positional encoding. This multi-functionality reduces the number of components and improves measurement precision.
2Measurement precision
If additional encoder hardware is added to improve positional accuracy, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
The patent merges the motor and encoder into a single integrated unit. The rotor contains permanent magnets that serve both motor function and encoding function, eliminating separate encoder hardware and reducing overall device complexity while achieving high positional resolution through signal processing of the combined magnetic field.
Solution Approach 2:
The motor's own permanent magnets serve the dual purpose of generating motor torque and providing positional encoding information. The system uses its inherent magnetic field structure to provide encoding signals, eliminating the need for external encoder components.
3Ease of operation
If conventional motion control with hardware encoders is implemented, then speed control is achieved, but mechanical packaging becomes large and complex
Solution Approach 1:
The patent integrates the encoder functionality within the motor structure itself. The control electronics process signals from the motor's own permanent magnets to provide both commutation and positional feedback, eliminating the need for separate encoder hardware and reducing the overall motor package size.
Solution Approach 2:
The permanent magnets and control system perform multiple functions: motor commutation, speed control, and positional feedback. This multi-functionality reduces the number of separate components needed, resulting in a more compact motor package while maintaining full motion control capability.
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 provides a compact, cost-effective, and high-resolution motion control system for BLDC motors, enabling precise positioning and commutation without the need for additional encoder hardware, suitable for small-scale applications like diagnostic systems and robotic devices.
Implementation Method 1
Commutation for brushless DC (BLDC) electric motors typically employ Hall-effect sensors to sense movement of permanent magnets in operation of the motors
Implementation Method 2
sense movement of permanent magnets in operation of the motors
Data Source
AI summary
A DC electric motor having a stator mounted to a substrate, the stator having a coil assembly having a magnetic core, a rotor mounted to the stator with a first set of permanent magnets distributed radially about the rotor to facilitate rotation of the rotor and a second set of permanent magnets on the rotor to facilitate determination of an absolute position of the rotor. The motor further includes first and second set of sensors for detection of the magnets of the inner and outer rings. During operation of the motor passage of the permanent magnets over the sensors produces a substantially sinusoidal signal of varying voltage substantially without noise and/or saturation, allowing an absolute position of the rotor relative the substrate to be determined from the sinusoidal signals without requiring use of an encoder or position sensors and without requiring noise-reduction or filtering of the signal.