Electrical Machine Rotor Axial Bore Cooling Design
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Solution Overview
Problem
Existing electrical machines face challenges in achieving high efficiency and power density while maintaining effective cooling, particularly in weight-sensitive applications such as wind turbines and electric vehicles, where traditional cooling methods can impair operation or lead to increased material usage and cost.
Innovation Solution
The design incorporates a rotor with an axial bore and an inflow element for a cooling liquid to flow through, allowing for efficient heat dissipation without contacting electrical components, and a coolant circuit that operates independently of the machine's operational state or speed, utilizing a combination of axial and radial boundaries to guide the coolant effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional cooling methods are used, then cooling effectiveness is improved, but the electrical machine's operation is impaired or material usage increases
Solution Approach 1:
The cooling liquid flow path is extracted from the stator side and redirected through the rotor's axial bore. The inflow element extends into the axial bore to introduce cooling liquid directly into the rotor's internal cooling passage, separating the cooling function from the stator structure and enabling effective rotor cooling without interfering with stator electrical components
Solution Approach 2:
The cooling liquid acts as an intermediary medium that transfers heat from the rotor to the environment. The coolant circuit system serves as an intermediary structure that delivers and removes the cooling liquid through the rotor, enabling heat dissipation without direct contact between cooling components and electrical parts
2Temperature
If cooling liquid is used, then cooling efficiency is improved, but electrical components are contacted by the cooling liquid
Solution Approach 1:
The cooling liquid flow path is extracted from the stator side and redirected through the rotor's axial bore. The inflow element extends into the axial bore to introduce cooling liquid directly into the rotor's internal cooling passage, separating the cooling function from the stator structure and enabling effective rotor cooling without interfering with stator electrical components
Solution Approach 2:
The cooling liquid acts as an intermediary medium that transfers heat from the rotor to the environment. The coolant circuit system serves as an intermediary structure that delivers and removes the cooling liquid through the rotor, enabling heat dissipation without direct contact between cooling components and electrical parts
3Power
If high power density is achieved, then material usage is reduced, but cooling effectiveness deteriorates
Solution Approach 1:
The cooling approach transitions from external/stator-based cooling to internal/rotor-based cooling by utilizing the axial bore dimension. The cooling liquid flows axially through the rotor's internal passage, accessing heat sources directly within the rotor volume and enabling effective cooling in compact, high-power-density configurations
Solution Approach 2:
A hydraulic cooling system is implemented using cooling liquid instead of air or other gases. The liquid coolant circuit provides superior heat transfer capabilities through the rotor's axial bore, enabling effective thermal management in high-power-density applications where conventional cooling would be insufficient
4Temperature
If rotor cooling is implemented, then heat dissipation is improved, but pressure losses increase
Solution Approach 1:
The axial bore and inflow element are pre-configured in the rotor design to create an optimized flow path. The cooling liquid is introduced at the optimal location and direction before entering the cooling passage, reducing flow resistance and pressure losses while maximizing heat dissipation efficiency
Solution Approach 2:
The cooling system parameters (flow path geometry, inlet position, passage dimensions) are optimized to minimize pressure losses. The axial bore configuration and inflow element positioning are specifically designed to reduce flow resistance and turbulence, enabling effective cooling with lower energy penalties
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 solution enables efficient cooling at high rotational speeds, reduces pressure losses, and allows for a cost-effective design with lower energy consumption, maintaining efficient operation across various operating conditions without compromising the rotor's movement or increasing material usage.
Implementation Method 1
a cooling liquid can flow from the inflow element into the axial bore
Implementation Method 2
a coolant circuit for transporting the coolant through the axial bore
Data Source
Figure 1
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AI summary
The invention relates to an electrical machine (1, 51), in particular an asynchronous machine, comprising a stator (2), a rotor (4) which is rotatably mounted about a rotation axis (3) and magnetically interacts with the stator (2) during operation of the electrical machine (1, 51), a shaft (5) on which the rotor (4) is fixed and which has an axial hole (6), and an inflow element (7, 47) which extends into the axial hole (6) such that a coolant (15), in particular a cooling liquid (15), can flow into the axial hole (6) from the inflow element (7, 47). The invention also relates to a cooling system (50) comprising an electrical machine (1, 51) and a coolant circuit (55) for transporting the coolant (15), in particular the cooling liquid (15), through the axial hole (6), and to a vehicle (61) comprising a cooling system (50).