Rotor Cooling Channel Layout for Eddy Loss Heat in Electric Machines
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Solution Overview
Problem
Electric motors, particularly in high-voltage applications, generate excessive heat due to eddy current losses, affecting efficiency and potentially leading to demagnetization and damage, with existing fluid cooling systems being inadequate.
Innovation Solution
A rotor assembly with an internal fluid cooling system featuring cooling channels and end plate channels that enhance fluid filling levels, utilizing centrifugal force to improve cooling efficiency by guiding cooling fluid through the rotor and potentially the stator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional cooling systems are used in rotor assemblies, then the structure is simpler, but cooling efficiency is insufficient to manage heat from eddy current losses
Solution Approach 1:
The cooling system is segmented into multiple cooling channels distributed around the rotor core, with each channel independently configured to optimize fluid flow and heat dissipation. The downstream end plate channel is further segmented into multiple radial positions to create varying filling levels in different zones of the rotor.
Solution Approach 2:
The invention introduces a radial dimension variation in the downstream end plate channel configuration, where the radially innermost position of the radially outer wall portion is arranged inward of the radially innermost position of the radially inner wall portion. This creates a three-dimensional filling level gradient that enhances cooling efficiency without adding complex external structures.
2Quantity of substance
If the radially outer wall portion is positioned outward, then the cooling channel volume is larger, but the filling level of cooling fluid decreases under centrifugal force
Solution Approach 1:
The invention changes the geometric parameters of the downstream end plate channel by positioning the radially outer wall portion inward relative to the radially inner wall portion. This parameter modification creates a filling level gradient that optimizes cooling fluid distribution under centrifugal force, ensuring adequate filling even in outer regions of the rotor.
3Power
If cooling fluid filling level is increased, then cooling power is improved, but the risk of fluid leakage and mechanical stress increases
Solution Approach 1:
The invention applies local quality by creating different filling levels in different radial zones of the cooling system. The downstream end plate channel is configured with its radially outer wall portion positioned inward, which locally optimizes the filling level in outer regions while maintaining appropriate volumes in inner regions, thereby balancing cooling power with leakage risk mitigation.
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 enhanced cooling system increases cooling power and efficiency, reducing heat-related issues and improving motor performance.
Implementation Method 1
The at least one fluid cooling pathway (110) is configured to guide cooling fluid through the rotor (30)
Implementation Method 2
at least one cooling channel (124, 126) extending through the rotor core (32) from the first axial end (32a) to the second axial end (32b)
Implementation Method 3
Particularly in operating conditions where the centrifugal force is higher than the gravity force the filling level of cooling fluid in the at least one cooling channel can be increased
Data Source
AI summary
The present disclosure relates to a rotor assembly for an electric machine. The rotor assembly comprises a rotating shaft, a rotor and a fluid cooling system. The rotor is fixed to the rotating shaft. The rotor comprises a rotor core, a first end plate and a second end plate. The first end plate is provided at a first axial end of the rotor core. The second end plate is provided at a second axial end of the rotor core. The fluid cooling system comprises at least one fluid cooling pathway provided internally in the rotor. The at least one fluid cooling pathway is configured to guide cooling fluid through the rotor, and comprises at least one cooling channel and a downstream end plate channel. The at least one cooling channel extends through the rotor core from the first axial end to the second axial end. The downstream end plate channel is fluidically connected to a downstream end of the at least one cooling channel. The downstream end plate channel is restricted radially outwards by a radially outer wall portion. The at least one cooling channel is restricted radially inwards by a radially inner wall portion. A radially innermost position of the radially outer wall portion is arranged in a range about or at or radially inwards of a radially innermost position of a radially inner wall portion.