Synchronous Motor Rotor Axial Protuberances Sensorless Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing synchronous motors require external sensor devices to control rotor positioning, which increases the motor's length and complexity, and slotless designs complicate inductance-based sensorless control methods.
Innovation Solution
A cylindrical rotor with permanent magnets and axial protuberances is integrated into a tubular slotless stator winding, allowing the rotor's geometry to function as a magnetic sensor for position feedback, eliminating the need for external sensors and optimizing inductance variation for position detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external sensor devices are used to control rotor positioning, then positioning accuracy is improved, but device complexity and motor length increase
Solution Approach 1:
The patent merges the rotor structure with the position detection function by integrating axial protuberances directly into the rotor body. These protuberances work with the slotless stator winding to create inductance variations that indicate rotor position, eliminating the need for separate external sensor devices while maintaining positioning accuracy.
Solution Approach 2:
The rotor structure serves dual purposes: it generates magnetic fields for motor operation and simultaneously provides position detection information through its geometric features (axial protuberances). The rotor essentially detects its own position through the inductance variations it creates in the slotless stator winding.
2Measurement precision
If external sensor devices are used to control rotor positioning, then positioning accuracy is improved, but motor length increases
Solution Approach 1:
The patent integrates the position detection function into the existing motor structure by using axial protuberances on the rotor that interact with the slotless stator winding. This merging eliminates the need for additional external sensor components that would extend the motor length, while still providing accurate rotor position information through inductance variations.
3Power
If permanent magnets are placed on the circumferential surface of the rotor, then motor efficiency is improved, but inductance variation for sensorless control is reduced
Solution Approach 1:
The patent segments the rotor structure by adding axial protuberances that extend from the circumferential surface. These protuberances create distinct inductance variations as they pass by the slotless stator winding phases, providing sufficient signal for sensorless control while the circumferential permanent magnets maintain motor efficiency.
Solution Approach 2:
The patent applies different geometric features to different parts of the rotor: circumferential permanent magnets for efficient magnetic field generation and axial protuberances for position detection. This local differentiation allows each feature to optimize its specific function without compromising the other.
4Ease of manufacture
If a slotless stator design is used, then manufacturing simplicity is improved, but inductance variation for sensorless control becomes less obvious
Solution Approach 1:
The patent introduces asymmetry into the rotor structure through axial protuberances that create asymmetric inductance variations as they rotate past the slotless stator phases. This asymmetric geometric feature ensures detectable inductance modulation despite the uniform slotless stator design, enabling sensorless control while maintaining manufacturing simplicity.
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 design reduces motor length, simplifies position detection, and maintains constant inductance values across phases, enabling effective sensorless control without external sensors and minimizing reluctance variation.
Implementation Method 1
a cylindrical rotor comprising a hollow body made out of material having electromagnetic permeability mounted on a cylindrical rotor shaft, said cylindrical rotor body being provided with pairs of permanent magnets, said rotor being located inside a tubular stator provided with a tubular winding
Implementation Method 2
the coils of the tubular winding will be sensitive to the presence or not of the rotor material close to them and sensitive to the change of the inductance value when the rotor rotates
Data Source
AI summary
The present invention relates to synchronous motor comprising a cylindrical rotor (4) provided with permanent magnets (3) located inside a cylindrical stator provided with a winding (U, V, W), characterized in that the rotor is provided with protuberances (41) facing the said winding.