Outer Rotor Motor Position Encoder PCB Integration
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Solution Overview
Problem
Outer rotor direct drive motors face challenges with position encoder selection due to limited resolution of current encoders, which affects motor control accuracy and efficiency, and existing encoders like magnetic and photoelectric encoders are either unsuitable or expensive for harsh environments.
Innovation Solution
An electromagnetic induction position encoder is integrated into the motor design, featuring a stator and rotor printed circuit boards with conductive material scale areas and sawtooth structures to enhance coupling strength and resolution without increasing motor size or cost, supporting flexible installation and high accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetic effect encoders are installed on motor shaft ends, then position detection function is achieved, but installation space is insufficient and vibration/oil pollution damages reliability
Solution Approach 1:
The patent introduces an intermediary encoder structure that is coupled to the motor shaft through a flexible connection rather than direct mounting. This intermediary encoder body can be positioned away from the harsh motor shaft environment while still detecting shaft position through magnetic field interaction, isolating the encoder from vibration and oil pollution damage.
Solution Approach 2:
The encoder system is segmented into separate functional components: the encoder body containing sensitive elements is separated from the motor shaft, with only the magnetic coupling mechanism connecting them. This segmentation allows the sensitive encoder parts to be protected from harsh environmental factors while maintaining position detection functionality.
2Measurement precision
If simple three Hall switches are used for position detection, then basic current switching function is achieved, but resolution is limited to motor pole pairs causing poor control precision
Solution Approach 1:
The patent changes the fundamental parameter of position detection from counting pole pairs (limited resolution) to measuring absolute angular position through optical or magnetic encoder scales. This parameter change enables resolution independent of motor pole pair count, achieving high precision position feedback without proportionally increasing device complexity.
3Measurement precision
If photoelectric encoders are used for position detection, then high resolution is achieved, but cost increases and they are damaged by harsh working environments
Solution Approach 1:
The patent replaces photoelectric detection mechanisms with magnetic field-based detection. Magnetic encoders use magnetic fields instead of light, making them immune to dust, moisture, and other environmental factors that damage photoelectric components, while maintaining high resolution position detection capability.
4Force
If outer rotor direct drive motor design is adopted to maximize output torque, then torque is increased, but no space is left for encoder installation on motor shaft
Solution Approach 1:
The patent uses an intermediary coupling mechanism between the motor shaft and encoder that requires minimal space. The encoder is mounted externally and couples to the rotating shaft through magnetic or flexible mechanical connection, allowing encoder integration in the compact outer rotor design without compromising torque output or requiring significant additional space.
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
The electromagnetic induction position encoder provides high-resolution signals, improving motor control precision and energy efficiency while withstanding harsh environments without additional structural changes or costs.
Implementation Method 1
at least an excitation coil and a receiving coil being printed at the stator printed circuit board... the outer rotor changes a coupling strength between the excitation coil and the receiving coil
Implementation Method 2
the outer rotor changes a coupling strength between the excitation coil and the receiving coil
Data Source
AI summary
An outer rotor direct drive motor with a position encoder includes an outer rotor and a stator disposed in the outer rotor, wherein the stator includes: a stator chassis; a stator printed circuit board disposed on an side of the stator chassis, at least an excitation coil and a receiving coil being printed at the stator printed circuit board; and a stator winding disposed on the stator printed circuit board; wherein the outer rotor changes a coupling strength between the excitation coil and the receiving coil. The present invention has the following advantages: the installation method is flexible, and supports through-shaft installation without occupying too much space of the motor body; the sensor structure is stable, the rotor scale area and the induction coil are all printed on the printed circuit board, even in the case where the rotational speed is too fast, deformation or cracking will not be occurred.