Liquid-Cooled EV Charging Cable for High-Current Heat Management
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Solution Overview
Problem
Conventional heavy-current charging cables for electric vehicles face challenges with heat management at high currents, leading to increased weight, stiffness, and reliability issues due to the need for large cross-sections and active liquid cooling systems.
Innovation Solution
A heavy-current charging cable design featuring a ground heavy-current wire and heavy-current power wires with a liquid tight inner sheath and outer sheath, allowing for efficient liquid coolant flow to manage heat, while maintaining mechanical robustness and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional charging cables with large cross-section are used for high current applications, then the current carrying capacity is improved, but the cable becomes too heavy and stiff for the user
Solution Approach 1:
The cable is divided into multiple conductors (e.g., multiple copper strands) instead of a single solid conductor. This segmentation allows the cable to maintain high current carrying capacity while reducing overall weight and improving flexibility, as each thin strand contributes to the total current capacity without requiring a massive single conductor
Solution Approach 2:
The cable uses composite construction combining copper conductors with polymer insulation and cooling channels. This composite structure enables efficient heat dissipation through the cooling liquid pathways while maintaining electrical conductivity, allowing high power transmission without excessive weight or stiffness
2Temperature
If active liquid cooling system is implemented for currents above 250 A, then heat removal capability is improved, but the device complexity increases
Solution Approach 1:
The cooling channels are integrated directly into the cable structure itself, merging the cooling function with the cable body. The cooling liquid flows through hollow channels formed within the cable's insulation layers, eliminating the need for separate external cooling systems and reducing overall device complexity while maintaining effective heat removal
Solution Approach 2:
The system uses liquid coolant (water/glycol mixture) flowing through hydraulic channels to transfer heat away from the conductors. The hydraulic cooling mechanism provides efficient heat removal through forced convection, managing thermal loads at high currents without requiring complex mechanical cooling components
3Temperature
If non-insulating coolants like water/glycol mixtures are used, then thermal properties are improved, but cooling performance is penalized due to insulating layers between conductors and cooling liquid
Solution Approach 1:
The cable structure is designed with varying insulation thicknesses in different regions. Areas closer to the cooling channels have reduced insulation thickness or enhanced thermal conductivity materials, creating local quality variations that prioritize heat transfer to the coolant in critical zones while maintaining electrical insulation where needed. This localized optimization improves cooling efficiency without compromising safety
Solution Approach 2:
The cooling liquid acts as an intermediary heat transfer medium between the conductors and the external environment. The liquid coolant absorbs heat from the conductors through thermal conduction across minimal insulation barriers, then transports the thermal energy away through convection, efficiently bridging the heat transfer gap while maintaining electrical isolation
4Temperature
If refrigeration loop cooling unit is used to decrease working temperature at high ambient temperature, then temperature control is improved, but the system becomes more expensive and less reliable
Solution Approach 1:
The cable's cooling channels and liquid circulation system provide passive thermal management that automatically responds to heat generation. The cooling liquid continuously flows through the channels, absorbing heat as it passes, providing self-regulating temperature control without requiring active refrigeration cycles or complex temperature-controlled components, thereby reducing system complexity and cost
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 proposed solution enables high-power charging up to 500 kW with improved thermal and mechanical performance, reduced conductor temperatures, and enhanced reliability and safety, while being cost-effective and scalable.
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. Such active liquid cooling system typically comprises a liquid coolant... for removing heat from conductors and power contact elements
Implementation Method 2
removing heat generated by Joule effect both in the charging cable and in a charging connector
Data Source
AI summary
A charging cable includes a ground conductor and extending in a longitudinal direction, at least two heavy-current power wires for conducting positive and negative direct current, each comprising a power conductor and insulation, the heavy-current power wires extending parallel to the ground wire, a liquid tight inner sheath extending in the longitudinal direction and surrounding the heavy-current power wires to define a first hollow area between and around the heavy-current power wires, liquid coolant being provided between the heavy-current power wires along the longitudinal direction, wherein the liquid tight inner sheath comprises a second hollow area extending in the longitudinal direction, arranged adjacent to at least one of the heavy-current power wires and comprising liquid coolant to flow within the second hollow area, and a liquid tight outer sheath extending in the longitudinal direction and surrounding the inner sheath and the ground heavy-current wire.