V-Shaped Motor Rotor Structure for Low Torque Ripple
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Solution Overview
Problem
Permanent magnet synchronous motors in electric vehicles experience torque fluctuations and harmonic content due to non-ideal motor body structures and nonlinear inverter characteristics, leading to increased noise, vibration, and reduced efficiency.
Innovation Solution
A motor rotor design with a rotor core and permanent magnets arranged in V-shaped mounting slots, along with flux barriers and relief grooves, is implemented to constrain key dimensions and reduce no-load counter-electromotive force harmonics and torque ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the motor uses a conventional rotor structure with permanent magnets, then the motor can generate torque, but the torque fluctuates due to magnetic field harmonics and inductance harmonics
Solution Approach 1:
The patent applies asymmetry by designing the rotor core with an asymmetric magnetic circuit structure. The rotor includes a rotor core with mounting slots arranged asymmetrically, and permanent magnets positioned in these slots create an asymmetric magnetic field distribution. This asymmetric design balances the magnetic field harmonics and reduces torque fluctuation while maintaining effective torque generation.
Solution Approach 2:
The patent implements local quality by creating different magnetic circuit paths in different regions of the rotor. The rotor core has varying magnetic permeability in different areas, with specific regions designed to guide and balance magnetic flux. This local variation in magnetic properties helps equalize the magnetic field distribution and reduce harmonics, thereby stabilizing torque output.
2Loss of energy
If the motor operates with high power density, then the motor efficiency is improved, but the torsional vibration of the powertrain increases
Solution Approach 1:
The patent addresses torsional vibration by designing the rotor structure to reduce magnetic field harmonics that cause electromagnetic vibrations. The asymmetric rotor configuration and optimized permanent magnet positioning create a more uniform magnetic field, reducing the electromagnetic forces that induce torsional vibration in the powertrain while maintaining high power density and efficiency.
3Quantity of substance
If the motor uses a built-in permanent magnet rotor structure, then the permanent magnet utilization rate increases, but the rotor design complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the rotor into modular components: a rotor core with multiple mounting slots, and separate permanent magnets positioned in these slots. This segmented design allows for optimized permanent magnet placement to maximize utilization while keeping each component relatively simple in structure, thereby reducing overall manufacturing complexity despite high magnet utilization.
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 design effectively reduces harmonic content and torque ripple to less than 3%, enhancing the smoothness of output torque, reducing vibration and noise, and improving the overall efficiency and safety of the electric vehicle.
Implementation Method 1
The permanent magnets will generate magnetic flux, including radial magnetic flux and tangential magnetic flux
Implementation Method 2
The radial electromagnetic force is the interaction force between the stator core and the rotor
Implementation Method 3
The air-gap magnetic field formed by the main flux will act on the rotor, causing deformation of the stator core and the rotor of the motor, resulting in cyclic vibration
Data Source
AI summary
The present disclosure relates to a motor rotor, a permanent magnet motor, and an electric vehicle. The motor rotor includes a rotor core (1) and permanent magnets (3). The rotor core (1) includes mounting slots (2). The permanent magnets (3) are arranged in the mounting slots (2). An included angle between two mounting slots (2) forming a V-shaped structure in the mounting slots (2) is Δ. A numerical value of a thickness of the permanent magnets (3) is L4 when a unit thereof is mm. A numerical value of a width of the permanent magnets (3) is L5 when a unit thereof is mm. 110°≤Δ≤140°. A numerical value of Δ=(18 to 20)*L4, L5≥2*L4.