Liquid-Cooled EV Charging Cable With Dual Coolant Channels
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Solution Overview
Problem
Conventional charging cables for electric vehicles face limitations in thermal performance, mechanical robustness, reliability, and safety at high charging currents due to the use of non-insulating coolants and complex cooling systems, which result in increased weight, stiffness, and potential safety hazards.
Innovation Solution
A heavy-current charging cable design with a cylindrical shape, featuring a liquid tight inner and outer sheath, a first and second hollow area for coolant flow, and a flexible metal tube for enhanced mechanical protection, allowing efficient cooling and scalability to higher power ratings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional charging cables use non-insulating coolants for cooling, then cooling efficiency is improved, but safety and reliability deteriorate due to potential contact with living parts and chemical compatibility issues
Solution Approach 1:
The cooling system is segmented into multiple independent channels: an inner hollow channel for non-insulating coolant (water/glycol) providing efficient cooling, and an outer annular channel for insulating coolant providing safety and chemical compatibility. This segmentation allows each coolant to perform its specialized function without compromising the other.
Solution Approach 2:
The insulating coolant in the outer annular channel acts as an intermediary safety layer between the non-insulating coolant and the environment. It prevents direct contact with living parts while allowing the non-insulating coolant to maintain efficient thermal contact with conductors through the inner channel.
2Power
If charging cables are designed with large cross section for high current, then current carrying capacity is improved, but weight and stiffness increase making them too heavy and stiff for users
Solution Approach 1:
The patent replaces solid conductor material with hollow channels that circulate liquid coolant. This hydraulic approach allows heat removal through fluid convection, enabling the use of thinner conductor walls while maintaining high current capacity, thus reducing overall cable weight and improving flexibility.
Solution Approach 2:
The cable employs composite construction with inner and outer sheaths made of different materials optimized for their specific functions. The inner sheath provides electrical insulation and structural support, while the outer sheath provides mechanical protection and flexibility, creating a lightweight yet robust composite structure.
3Temperature
If liquid coolant flows directly around bare conductors, then cooling performance is improved, but thermal performance at high ambient temperature deteriorates requiring derating of maximum charging current
Solution Approach 1:
The cooling system is divided into two independent channels: the inner channel provides direct coolant contact with conductors for high cooling performance, while the outer annular channel provides thermal isolation from ambient temperature. This segmentation allows the inner channel to maintain efficient heat removal even when ambient temperatures are high.
Solution Approach 2:
The outer annular channel filled with insulating coolant acts as a thermal intermediary layer that isolates the inner cooling channel from ambient temperature fluctuations. This allows the inner channel to maintain its cooling efficiency independent of external thermal conditions, preventing the need for current derating.
4Temperature
If refrigeration loop with evaporator and condenser is used to decrease working temperature, then conductor temperature control is improved, but device complexity and cost increase
Solution Approach 1:
The dual-channel cooling system is designed to be self-regulating. The inner channel provides active cooling through coolant circulation, while the outer channel passively provides thermal isolation and protection. The system automatically maintains conductor temperature within acceptable ranges through the combined action of both channels without requiring complex external refrigeration control.
Solution Approach 2:
The outer annular channel serves multiple functions simultaneously: it provides thermal isolation from ambient temperature, mechanical protection for the inner channel, chemical compatibility with the non-insulating coolant, and safety isolation. This multi-functionality eliminates the need for separate refrigeration components, simplifying the overall system.
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 cable achieves improved thermal and mechanical performance, safety, and ease of manufacturing, enabling charging at 500A and 1000V with reduced conductor temperatures and reduced weight, while being scalable to higher power ratings.
Implementation Method 1
an active liquid cooling system is essential for removing heat generated by Joule effect both in the charging cable and in a charging connector connected to the charging cable
Implementation Method 2
a liquid coolant, such as for example a synthetic coolant, oil, water/glycol or water/salts mixtures, halogenated hydrocarbon compounds, etc., for removing heat from conductors
Implementation Method 3
In an evaporator, i.e. in the refrigerant-to-coolant heat exchanger, the heat coming from the conductors is transferred to the refrigerant. The refrigerant is then compressed and the heat is finally released to ambient air in a condenser.
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a heavy-current charging cable (1) for charging an electric vehicle, comprising a ground heavy-current wire (2) configured for serving as ground, the ground heavy-current wire (2) comprising a ground conductor (3) and extending in a longitudinal direction, at least two heavy-current power wires (5) configured for conducting positive and negative direct current, DC, each of said heavy- current power wires (5) comprising a power conductor (6) and a power wire insulation (7) surrounding said power conductor (6), the heavy-current power wires (5) extending parallel to the ground wire, a liquid tight inner sheath (8) extending in the longitudinal direction and surrounding the heavy-current power wires (5) thereby defining a first hollow area (10) between and around the heavy-current power wires (5) comprising liquid coolant to flow between the heavy-current power wires (5) along the longitudinal direction, whereby the liquid tight inner sheath (8) comprises a second hollow area (12) extending in the longitudinal direction, arranged adjacent to at least one of the heavy-current power wires (5) and comprising liquid coolant to flow within the second hollow area (12) along the longitudinal direction, and a liquid tight outer sheath (9) extending in the longitudinal direction and surrounding the inner sheath (8) and the ground heavy-current wire (2).