Ferrite Spoke-Type PMSM Layout for Low-Ripple Electric Truck Torque
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current medium-duty electric truck motors are too heavy, expensive, and inefficient to meet the growing demand for lighter, cost-effective, and energy-efficient solutions.
Innovation Solution
A six-phase electric motor design featuring an annular stator with dual three-phase windings offset by 75 degrees, a spoke-type rotor with ferrite permanent magnets, and a nonmagnetic shaft, which eliminates the use of rare earth magnets, reducing torque ripple and induced voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional medium-duty electric truck motors are used, then they can provide sufficient torque, but they are too heavy, expensive, and inefficient
Solution Approach 1:
The motor is divided into two independent three-phase winding sets (first and second three-phase windings) that are circumferentially offset by 75 degrees, allowing each set to contribute independently to torque production and reducing overall energy losses through distributed winding configuration
Solution Approach 2:
The motor combines ferrite permanent magnets with specific magnetic steel sheets (27G or 29G) in the rotor core, creating a composite magnetic circuit that improves magnetic flux density and reduces eddy current losses, thereby enhancing energy efficiency
2Weight of moving object
If conventional motors are used, then they can operate at required speeds, but they are too heavy for medium-duty trucks
Solution Approach 1:
The motor achieves high speed capability through optimized electrical parameters including 75-degree circumferential offset between winding sets, specific pole counts (12 or 14 poles), and tailored magnetic circuit design that reduces rotational inertia while maintaining magnetic flux density for high-speed operation
Solution Approach 2:
The design extracts and eliminates unnecessary components and materials from conventional motors, using ferrite magnets instead of heavy rare-earth alternatives, and optimizing the magnetic circuit to reduce overall motor weight while preserving speed performance
3Ease of manufacture
If ferrite permanent magnets are used in the rotor, then cost is reduced and rare earth materials are eliminated, but magnetic strength may be compromised
Solution Approach 1:
The motor uses ferrite permanent magnets combined with high-permeability magnetic steel sheets (27G or 29G) in the rotor core, creating a composite magnetic circuit that compensates for ferrite's lower intrinsic magnetic strength through optimized magnetic flux paths and reduced magnetic reluctance
Solution Approach 2:
The design optimizes ferrite magnet geometry, positioning, and magnetization direction, along with adjusting the number of poles and winding configurations, to maximize the effective magnetic flux density produced by ferrite magnets, achieving required magnetic strength without rare-earth materials
4Object-generated harmful factors
If dual three-phase windings with 75-degree offset are used, then torque ripple is reduced and efficiency is improved, but device complexity increases
Solution Approach 1:
The motor employs asymmetric winding distribution with two three-phase sets offset by 75 degrees circumferentially, creating an asymmetric magnetic field pattern that smooths torque production and reduces torque ripple through complementary torque contributions from each winding set
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 motor achieves high torque, low torque ripple, and high maximum speed, making it suitable for electric trucks with improved efficiency and cost-effectiveness.
Implementation Method 1
Flux from the four or more permanent magnets interacts with a stator magnetic field created by a current flowing through the first and second three-phase set of concentrated windings to cause the rotor to turn about the rotor axis
Implementation Method 2
Flux from the four or more permanent magnets interacts with a stator magnetic field created by a current flowing through the first and second three-phase set of concentrated windings to cause the rotor to turn about the rotor axis
Implementation Method 3
The rotor includes four or more permanent magnets circumferentially spaced around the rotor axis. Flux from the four or more permanent magnets interacts with a stator magnetic field
Data Source
AI summary
Various implementations include a six-phase electric motor including an annular stator and a rotor. The stator defines an opening having an inner surface. First and second three-phase sets of concentrated windings are circumferentially spaced along the inner surface of the opening. The first and second sets of concentrated windings are circumferentially offset from each other. The stator defines voids located radially outwardly from, and circumferentially between, each of the windings. The rotor includes permanent magnets circumferentially spaced around the rotor axis. The outer circumferential surface of the rotor defines grooves located circumferentially between each of the permanent magnets. The rotor is disposed within the stator opening such that the stator and rotor are coincident with each other. Flux from the permanent magnets interacts with a stator magnetic field created by a current flowing through the first and second sets of concentrated windings to cause the rotor to rotate.