IPM Motor Torque Ripple Reduction via Segmented Stator Teeth
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Solution Overview
Problem
Interior Permanent Magnet (IPM) motors experience significant torque ripple and cogging torque due to interactions between rotor magnets and stator slots, limiting the potential for reducing torque ripple and increasing motor output torque, especially at low speeds.
Innovation Solution
The design features a rotor assembly with rectangular magnet pockets and a stator assembly with planar stator teeth, where the stator teeth have equal leading and trailing chord lengths, and a segmented stator assembly with angled segment interface lines to minimize torque ripple and maximize output torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If traditional IPM motor design with rectangular magnets and simple stator slots is used, then manufacturing is simple, but torque ripple is significant
Solution Approach 1:
The stator tooth inner surface is divided into three distinct planar segments (leading, intermediate, trailing) with different orientations. Each segment has a specific chord length relationship (leading = trailing, intermediate = leading + trailing) to locally optimize the magnetic interaction at different positions along the tooth, reducing torque ripple while maintaining manufacturing feasibility
Solution Approach 2:
The stator tooth geometry introduces asymmetric planar surfaces with specific chord length relationships. The leading and trailing surfaces have equal chord lengths, while the intermediate surface has a chord length equal to their sum, creating an asymmetric configuration that balances magnetic forces and reduces cogging torque
2Weight of moving object
If magnet volume is reduced to decrease weight, then weight decreases, but torque output may be compromised
Solution Approach 1:
The patent optimizes the geometric parameters of the stator tooth planar surfaces, specifically the chord lengths of leading, intermediate, and trailing segments. By precisely controlling these dimensional parameters and their relationships, the magnetic field distribution is optimized to maintain torque output while allowing for reduced magnet volume
Solution Approach 2:
The segmented planar surfaces with specific chord length relationships create localized magnetic field optimizations that improve the efficiency of magnet utilization, allowing for reduced overall magnet volume while maintaining torque performance
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 configuration reduces torque ripple by 50% and increases average torque output by 4.5% at rated current while reducing magnet volume by 12%, improving the motor's electromagnetic torque response.
Implementation Method 1
The rotor assembly includes a plurality of permanent magnets distributed within the rotor assembly... The stator assembly includes a plurality of winding posts, each having a stator tooth... interact with the static structure (e.g., the slots) of the stator
Implementation Method 2
An Interior Permanent Magnet (IPM) motor comprises a plurality of magnet blocks that are embedded internally within the rotor core... the stator assembly hosts the motor windings
Data Source
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AI summary
Ann interior permanent magnet motor comprises a rotor assembly disposed within a stator assembly. The rotor assembly is configured for rotating about a central axis relatively to the stator assembly. The rotor assembly defines a plurality of magnet pockets within the rotor assembly along a radially outboard surface of the rotor assembly. Each magnet pocket is substantially rectangular in cross-sectional shape, and each magnet pocket is configured to facilitate insertion of a plurality of permanent magnets into and retention of the plurality of permanent magnets within, the magnet pocket. The rotor assembly further comprises a plurality of permanent magnet segments disposed in each magnet pocket.