Phase Change Material for Contactor Ice Prevention
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Solution Overview
Problem
Ice crystal formation between contacts of a contactor in hybrid or all-electric vehicles can prevent current flow, especially when ambient temperatures drop below freezing, causing operational delays and failures.
Innovation Solution
A phase change material is coupled to at least one conductor of the contactor, which absorbs and releases latent heat to maintain the contacts above freezing temperatures, preventing ice crystal formation without requiring modifications to the vehicle's controller or existing electrical circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contactor contacts are left open in cold conditions, then current flow is prevented, but moisture between the contacts freezes forming ice crystals that block future current flow
Solution Approach 1:
The patent applies phase transition by using a phase change material (such as paraffin wax or salt hydrate) that transitions between solid and liquid states. The material is positioned in thermal contact with the contactor contacts and undergoes phase change at temperatures near freezing point (0°C to 5°C). During vehicle operation, the material absorbs excess heat from the contacts (liquid phase). When the vehicle shuts down and contacts cool, the material releases stored latent heat as it transitions to solid phase, maintaining contact temperature above freezing and preventing ice crystal formation on the contacts.
Solution Approach 2:
The phase change material provides self-regulating thermal management without requiring external control systems. The material automatically absorbs heat when contacts are hot and releases heat when contacts cool, based solely on temperature-driven phase transitions. This passive mechanism eliminates the need for active heating elements, controllers, or power consumption, making the system self-sufficient and reliable in cold environmental conditions.
2Object-affected harmful factors
If active heating elements are used to prevent freezing, then ice crystal formation is prevented, but power consumption and system complexity increase
Solution Approach 1:
The phase change material provides self-regulating thermal management without requiring external control systems. The material automatically absorbs heat when contacts are hot and releases heat when contacts cool, based solely on temperature-driven phase transitions. This passive mechanism eliminates the need for active heating elements, controllers, or power consumption, making the system self-sufficient and reliable in cold environmental conditions.
Solution Approach 2:
The patent applies phase transition by using a phase change material (such as paraffin wax or salt hydrate) that transitions between solid and liquid states. The material is positioned in thermal contact with the contactor contacts and undergoes phase change at temperatures near freezing point (0°C to 5°C). During vehicle operation, the material absorbs excess heat from the contacts (liquid phase). When the vehicle shuts down and contacts cool, the material releases stored latent heat as it transitions to solid phase, maintaining contact temperature above freezing and preventing ice crystal formation on the contacts.
3Object-affected harmful factors
If the contactor contacts are kept closed to prevent freezing, then current flow is maintained, but the contactor cannot perform its switching function
Solution Approach 1:
The patent applies phase transition by using a phase change material (such as paraffin wax or salt hydrate) that transitions between solid and liquid states. The material is positioned in thermal contact with the contactor contacts and undergoes phase change at temperatures near freezing point (0°C to 5°C). During vehicle operation, the material absorbs excess heat from the contacts (liquid phase). When the vehicle shuts down and contacts cool, the material releases stored latent heat as it transitions to solid phase, maintaining contact temperature above freezing and preventing ice crystal formation on the contacts.
4Temperature
If rapid cooling of the main circuit occurs after vehicle shut-down, then system cooldown is achieved, but ice crystals form between the open contacts
Solution Approach 1:
The patent applies phase transition by using a phase change material (such as paraffin wax or salt hydrate) that transitions between solid and liquid states. The material is positioned in thermal contact with the contactor contacts and undergoes phase change at temperatures near freezing point (0°C to 5°C). During vehicle operation, the material absorbs excess heat from the contacts (liquid phase). When the vehicle shuts down and contacts cool, the material releases stored latent heat as it transitions to solid phase, maintaining contact temperature above freezing and preventing ice crystal formation on the contacts.
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 effectively inhibits ice crystal formation, ensuring uninterrupted current flow and vehicle operation by maintaining contactor temperatures above freezing, even in cold conditions, without additional power or actuation demands.
Implementation Method 1
a phase change material coupled to at least a first conductor of the set of conductors
Implementation Method 2
the phase change material is not positioned between the set of conductors... the cooling of conductor of a contactor after the vehicle is turned off may be slowed and passively maintained at a temperature above freezing
Data Source
AI summary
Methods and systems are provided for reducing contactor freezing. In one example, a system may include a contactor comprising a set of conductors and a phase change material. The phase change material is coupled to a first conductor of the set of conductors and is not positioned between the set of conductors.