Consequent-Pole Rotor Opening Design to Reduce Motor Noise

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Solution Overview

Problem

Conventional consequent-pole type rotors in electric motors experience increased noise due to magnetic flux passing through adjacent magnetic poles in the circumferential direction.

Innovation Solution

A consequent-pole type rotor design with a rotor core featuring magnet insertion holes and openings, where the first magnetic pole is formed by a permanent magnet inserted in the holes, and the openings are configured such that the maximum width in the radial direction is greater than in the perpendicular direction, ensuring the magnetic flux primarily flows through the second magnetic pole, reducing noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If magnetic flux flows from the stator to a pseudo-magnetic pole of the consequent-pole type rotor, then the rotor can function as a consequent-pole type rotor, but noise in the motor increases

Engineering Contradiction:

Improveconsequent-pole type rotor functionVSAvoidnoise

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The rotor core is segmented into multiple magnetic poles (first magnetic pole with permanent magnet, second magnetic pole without permanent magnet) with distinct regions. The openings are strategically positioned to segment the magnetic flux paths, ensuring flux from the stator flows primarily to the second magnetic pole rather than passing through the first magnetic pole, thereby reducing noise while maintaining consequent-pole functionality

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the rotor core are given different properties: the first magnetic pole region contains permanent magnets with specific magnetic characteristics, while the second magnetic pole region is designed without permanent magnets. The openings are locally positioned to control flux distribution, creating optimal local magnetic conditions that reduce noise generation

Inventive Principle:

Principle #3Local quality

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 effectively reduces noise in electric motors by preventing magnetic flux from passing through the first magnetic pole, maintaining sufficient magnetic force and motor efficiency while minimizing noise.

Implementation Method 1

a permanent magnet inserted in the magnet insertion hole and forming the first magnetic pole

Methodology Applied

Scientific EffectMagnetism: Magnetism

Implementation Method 2

magnetic flux flowing from the stator to a pseudo-magnetic pole of the consequent-pole type rotor

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS11342802B2Consequent-pole type rotor, electric motor, compressor, blower, and air conditioner

Publication Date: 2022.05.24 MITSUBISHI ELECTRIC CORP

AI summary

A rotor includes a rotor core including a magnet insertion hole and an opening and a permanent magnet inserted in the magnet insertion hole and forming a first magnetic pole. The rotor satisfies L1<L2, where L1 is a first maximum width of the opening in a direction perpendicular to a radial direction and L2 is a second maximum width of the opening in the radial direction. A distance from the opening to the magnet insertion hole is smallest at a magnetic pole center of the first magnetic pole.