Two-Layer V-Shaped Rotor Core Lamination for Higher Saliency Ratio

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Solution Overview

Problem

Conventional built-in permanent magnet synchronous motors in electric vehicles have a limited saliency ratio, leading to low utilization of reluctance torque and increased costs due to the need for a large permanent magnet quantity.

Innovation Solution

The design of a rotor core lamination with specific magnetic slot configurations, including V-shaped outer and inner magnetic slots, optimized to increase the saliency ratio by adjusting the width and angle of these slots, reducing the permanent magnet quantity required while maintaining motor performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a conventional rotor core design with limited saliency ratio is used, then the motor can operate with a simpler structure, but the utilization of reluctance torque is low and permanent magnet quantity must be increased to meet torque requirements

Engineering Contradiction:

Improvepermanent magnet quantityVSAvoid rotor core structure complexity

Core Design Contradiction:

Quantity of substanceVSEase of manufacture

Solution Approach 1:

The rotor core is divided into multiple laminations, each with specific magnetic slot configurations. The segmentation allows optimization of magnetic flux paths and saliency ratio while maintaining manufacturing feasibility through standardized lamination production

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the rotor core lamination are designed with different properties: outer magnetic slots have specific widths and angles optimized for reluctance torque, while inner magnetic slots have different dimensions. This local optimization increases the saliency ratio without requiring complete redesign of the entire rotor structure

Inventive Principle:

Principle #3Local quality

2Power

If the permanent magnet quantity is increased to achieve specified motor torque, then the motor torque requirement is met, but the costs increase

Engineering Contradiction:

Improvemotor torqueVSAvoidpermanent magnet quantity

Core Design Contradiction:

PowerVSQuantity of substance

Solution Approach 1:

The invention changes geometric parameters of the magnetic slots (widths, angles, positions) to optimize the saliency ratio. By adjusting these parameters, the reluctance torque is enhanced, allowing reduced permanent magnet quantity while maintaining the required motor torque output

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The magnetic slot design employs asymmetric configurations where outer magnetic slots and inner magnetic slots have different widths and angles. This asymmetry creates optimal magnetic flux distribution that maximizes reluctance torque, enabling reduced permanent magnet usage while achieving specified power output

Inventive Principle:

Principle #4Asymmetry

3Productivity

If the saliency ratio is increased through optimized magnetic slot design, then the utilization of reluctance torque is improved and permanent magnet quantity is reduced, but the manufacturing precision requirements increase

Engineering Contradiction:

Improvemotor efficiencyVSAvoidmagnetic slot dimensional precision

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The magnetic slot geometries are pre-optimized in the design stage with specific widths and angles that balance performance improvement with manufacturing capability. This preliminary optimization ensures that the enhanced saliency ratio is achieved through dimensions that can be manufactured with standard precision capabilities

Inventive Principle:

Principle #10Preliminary action

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 enhances the utilization of reluctance torque, reduces the permanent magnet quantity, and lowers costs by optimizing the magnetic reluctance and inductance ratios, thereby improving motor efficiency and power density.

Implementation Method 1

optimizing the magnetic reluctance and inductance ratios

Methodology Applied

Scientific EffectMagnetic reluctance: Magnetic Reluctance

Implementation Method 2

permanent magnet synchronous motor

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3989403B1Rotor core lamination, rotor core, rotor, permanent magnet synchronous electric motor, and related product

Publication Date: 2023.12.20 HUAWEI DIGITAL POWER TECH CO LTD

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AI summary

This application provides a rotor structure that is of a permanent magnet synchronous motor and that is applied to an electric vehicle. The rotor structure uses a built-in two-layer V-shaped magnetic pole structure. A magnetic pole included angle of an inner-layer V-shaped magnetic pole structure is greater than a magnetic pole included angle of an outer-layer V-shaped magnetic pole structure. A difference between the two angles is in [0°, 50°]. A width of a permanent magnet slot in the inner-layer magnetic pole structure is 1.5 times to 2 times a width of a permanent magnet slot in the outer-layer magnetic pole structure. This application further provides a permanent magnet synchronous motor including the rotor structure, a powertrain including the permanent magnet synchronous motor, and an electric vehicle including the powertrain. In the solutions of this application, a proper value matching is performed on the magnetic pole included angles of the inner magnetic pole structure and the outer magnetic pole structure and the width of the permanent magnet slot, to improve a saliency ratio of the permanent magnet synchronous motor and reduce a permanent magnet quantity, thereby reducing the costs.