Mn-Bi Magnet Rotor Cavities for Lower-Cost Synchronous Reluctance Motors

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Solution Overview

Problem

Current synchronous reluctance motors face challenges with high manufacturing costs due to the use of Neodymium-based magnets, especially in larger machines, where ferrites with lower intrinsic coercivity are not viable, leading to increased costs and magnetic saturation issues.

Innovation Solution

A permanent magnet rotor using Mn—Bi particles, which form a portion of the magnet, either as sintered or polymer bonded, with a thermoplastic or thermosetting polymer matrix, applied within a rotor body with cavities, offering a composite solution with high intrinsic coercivity and reduced processing temperatures through additives like lubricants and plasticizers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If Neodymium-based magnets are used in synchronous reluctance motors, then intrinsic coercivity and magnetic performance are improved, but manufacturing cost increases significantly

Engineering Contradiction:

Improveintrinsic coercivityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive Neodymium-based magnets with a cost-effective alternative using Mn-Bi particles combined with ferrite. This substitution maintains the required intrinsic coercivity while significantly reducing material costs, especially for larger motor frame sizes where Neodymium costs become prohibitive.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent creates a composite magnetic system combining Mn-Bi particles with ferrite material. This composite approach leverages the high intrinsic coercivity of Mn-Bi (comparable to Neodymium) while using the lower-cost ferrite as the base material, achieving a cost-effective solution that maintains magnetic performance.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If ferrite is used in synchronous reluctance motors, then manufacturing cost is reduced, but intrinsic coercivity is insufficient for larger machines

Engineering Contradiction:

Improvemanufacturing costVSAvoidintrinsic coercivity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies local quality enhancement by strategically placing Mn-Bi particles within the ferrite structure. Rather than using pure ferrite throughout, the Mn-Bi particles are distributed to provide localized high coercivity regions, ensuring the overall motor meets the intrinsic coercivity requirements for larger frame sizes while maintaining cost effectiveness.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Inventive Principle:

Principle #40Composite materials

3Reliability

If Mn—Bi particles are used to form magnets, then intrinsic coercivity comparable to Neodymium is achieved with reduced cost, but processing temperature requirements must be controlled

Engineering Contradiction:

Improveintrinsic coercivityVSAvoidprocessing temperature control

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent utilizes parameter changes by controlling the processing temperature within a specific range (180°C to 280°C) to optimize the Mn-Bi particle formation and magnetic properties. This temperature control enables the Mn-Bi particles to develop their high intrinsic coercivity characteristics while preventing degradation or unwanted phase changes.

Inventive Principle:

Principle #35Parameter changes

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 Mn—Bi particle-based magnets provide a cost-effective alternative with intrinsic coercivity comparable to Neodymium, reducing material and manufacturing costs while maintaining high magnetic performance across varying frame sizes, addressing the limitations of ferrites and Neodymium-based magnets.

Implementation Method 1

forming the at least one magnet includes heating the Mn—Bi particles at a temperature range based at least in part on the predetermined temperature

Methodology Applied

Scientific EffectSintering: Sintering

Implementation Method 2

the at least one magnet includes a polymer bonded magnet, wherein the polymer bonded magnet includes a composite of a polymer matrix and the Mn—Bi particles

Methodology Applied

Scientific EffectPolymer bonding: Binder

Implementation Method 3

an additive, wherein the additive includes a lubricant, a plasticizer, and a combination thereof, wherein the additive reduces a polymer melt viscosity to reduce a processing temperature

Methodology Applied

Scientific EffectViscosity reduction:

Implementation Method 4

applying a magnetic alignment field to the Mn—Bi particles; and sintering the Mn—Bi particles at the temperature range to form the at least one magnet

Methodology Applied

Scientific EffectMagnetic alignment: Magnetic Field

Data Source

PatentUS20250023398A1Permanent magnet assisted synchronous reluctance motors

Publication Date: 2025.01.16 ABB (SCHWEIZ) AG

AI summary

A permanent magnet rotor can include a rotor body and at least one magnet. The rotor body can include at least one rotor cavity. The at least one magnet includes, in part, Mn—Bi particles and the at least one magnet can be either a sintered magnet or a polymer bonded magnet. The at least one magnet can be located, at least partially, in the at least one rotor cavity. Further, the at least one magnet can be installed in the at least one rotor cavity after forming the at least one magnet or the at least one magnet can be formed in the at least one rotor cavity using a mold. Moreover, the polymer bonded magnet can include a composite of polymer matrix and Mn—Bi particles.