Interior Magnet Machine Angled Slots Cogging Torque
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Interior magnet machines face challenges such as lower power density, significant torque ripple, cogging torque, higher inductance, and increased drive cost due to trapezoidal air-gap flux distribution and rotor geometry, which affect noise, vibration, and power factor.
Innovation Solution
Incorporating angled slots between the magnet surface and the rotor outside diameter to alter the rotor flux distribution from trapezoidal to sinusoidal, reducing cogging torque and increasing the fundamental component of the flux distribution, thereby enhancing back-emf and torque production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If interior magnets are buried in the rotor core, then the machine structure is more robust and cooling is improved, but power density is reduced
Solution Approach 1:
The rotor core is segmented into multiple sections with magnets positioned in specific segments, allowing optimization of both structural integrity and magnetic flux paths for high power density
Solution Approach 2:
The invention transitions from conventional radial magnet positioning to a three-dimensional flux distribution achieved through specific winding arrangements and rotor geometry, increasing power density while maintaining structural robustness
2Device complexity
If a trapezoidal air-gap flux distribution is generated by interior magnet rotor, then the rotor structure is simple, but torque ripple is significant
Solution Approach 1:
The stator windings are designed with local variations in coil distribution and positioning to specifically address and smooth out the torque ripple caused by the trapezoidal flux distribution, while keeping the rotor structure simple
Solution Approach 2:
The invention modifies electrical parameters such as winding pitch, coil span, and current distribution to reduce torque ripple without changing the mechanical rotor structure, thereby maintaining simplicity while eliminating harmful effects
3Object-generated harmful factors
If skewing is used to reduce cogging torque, then cogging is reduced, but power density is lowered
Solution Approach 1:
The invention introduces an intermediary approach by using specific winding configurations and magnetic pole arrangements that indirectly reduce cogging torque through flux distribution optimization, rather than direct mechanical skewing that would reduce power density
Solution Approach 2:
The rotor employs composite construction with specific material properties in different regions to manage flux distribution and reduce cogging torque while maintaining high power density, avoiding the need for skewing
4Force
If higher inductance is present in interior magnet machines, then the machine can handle higher loads, but power factor is reduced and drive cost increases
Solution Approach 1:
The invention employs dynamic control strategies with power electronics to adjust operating parameters in real-time, optimizing the balance between inductance benefits for load handling and power factor maintenance, thereby reducing drive system costs
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 solution reduces cogging torque while maintaining or increasing back-emf and average torque, allowing for higher power density and reduced drive costs by optimizing rotor geometry and flux distribution.
Implementation Method 1
Incorporating angled slots between the magnet surface and the rotor outside diameter to alter the rotor flux distribution from trapezoidal to sinusoidal
Implementation Method 2
increasing the fundamental component of the flux distribution, thereby enhancing back-emf and torque production
Data Source
AI summary
An interior permanent magnet machine has non-contiguous, non-magnetic radial slots between the magnets and the cylindrical periphery and the magnets have non-magnetic radial end slots.