Permanent Magnet Rotor Cooling for Lower-Cost Traction Motors
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Solution Overview
Problem
The high manufacturing costs of electromagnetic machines with permanent magnet rotors and the need for effective thermal management in electric machines, particularly in traction motors for electrified vehicles, where heat dissipation is crucial.
Innovation Solution
The design includes a stator with radially disposed electrical conductors and a rotor with permanent magnets, featuring cooling channels and a heat pipe system to efficiently convey coolant fluids and manage heat, along with axial and radial magnet segmentation to reduce magnet losses and torque ripple, while minimizing the use of electrical steel and neodymium magnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If permanent magnet rotors are used in electromagnetic machines, then high specific torque, high specific power, and high efficiency are achieved, but manufacturing costs increase
Solution Approach 1:
The rotor is segmented into multiple independent magnet segments arranged around the rotor periphery, with each segment having its own recess and engaging member. This segmentation allows for reduced magnet material usage while maintaining performance, and enables modular manufacturing that reduces overall production costs.
Solution Approach 2:
An engaging member with a non-magnetic material is introduced as an intermediary between the magnet segment and the rotor body. This intermediary reduces magnetic losses by preventing eddy currents in the rotor body while providing mechanical retention, and it can be made from inexpensive non-magnetic materials.
2Force
If permanent magnet rotors are used in electromagnetic machines, then high specific torque and low torque ripple are achieved, but manufacturing costs increase
Solution Approach 1:
The rotor is segmented into multiple independent magnet segments arranged around the rotor periphery, with each segment having its own recess and engaging member. This segmentation allows for reduced magnet material usage while maintaining performance, and enables modular manufacturing that reduces overall production costs.
3Temperature
If cooling channels are added to manage heat in electric machines, then thermal management is improved, but device complexity increases
Solution Approach 1:
The cooling channels are merged with the existing structural components of the electric machine, specifically integrating them into the stator and rotor bodies. This eliminates the need for separate cooling system components and reduces overall system complexity while maintaining effective thermal management.
Solution Approach 2:
The stator and rotor bodies serve dual functions: they provide the electromagnetic structure necessary for machine operation and simultaneously serve as the cooling system through integrated channels. This multi-functionality reduces the number of separate components needed in the system.
4Loss of energy
If magnet segmentation is implemented to reduce magnet losses, then efficiency is improved, but device complexity increases
Solution Approach 1:
The rotor is segmented into multiple independent magnet segments arranged around the rotor periphery, with each segment having its own recess and engaging member. This segmentation allows for reduced magnet material usage while maintaining performance, and enables modular manufacturing that reduces overall production costs.
Solution Approach 2:
An engaging member with a non-magnetic material is introduced as an intermediary between the magnet segment and the rotor body. This intermediary reduces magnetic losses by preventing eddy currents in the rotor body while providing mechanical retention, and it can be made from inexpensive non-magnetic materials.
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 achieves similar output characteristics to traditional electromagnetic machines at lower manufacturing costs, with enhanced thermal management, reduced magnet losses, and minimal torque ripple, making it suitable for electrified vehicles.
Implementation Method 1
A cooling channel extends through the slot and is configured to convey a coolant fluid for removing heat from the stator
Implementation Method 2
The heat pipe is configured to absorb heat from the rotor by evaporating a refrigerant within the evaporator tube
Implementation Method 3
The heat pipe is also configured to transfer the heat away from the rotor by condensing the refrigerant to a liquid within the condenser
Implementation Method 4
An electrical current is applied or induced in the electrical conductors to generate a magnetic field that transfers energy to or from the rotating component
Data Source
AI summary
An electromagnetic machine includes a stator that includes a back plate and a plurality of electrical conductors radially disposed on the back plate. The electromagnetic machine also includes a rotor that includes a body having an outer diameter corresponding to an inner diameter of the stator and at least one magnet having a first end disposed proximate the stator and a second end disposed opposite the first end. The electromagnetic machine also includes an engaging member disposed on a shaft that extends axially relative to the rotor, the engaging member being configured to engage at least one recessed portion of the rotor.