Dielectric Plate Seal for Conductive Coolant Power Electronics
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Solution Overview
Problem
Existing liquid cooled power electronics assemblies face challenges in preventing electrical shorting and contamination from electrically conductive coolants, which can compromise the reliability and efficiency of power electronics, especially in high-voltage and high-current applications like electric vehicles.
Innovation Solution
A liquid cooled power electronics assembly is designed with a housing, electronic device, lead frame, and dielectric plates, along with a metallic sleeve that forms a seal to isolate the electronic device from the coolant, using a combination of ceramic dielectric plates and a metallic sleeve to prevent electrical contact and enhance heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If electrically conductive coolant is used to cool power electronic devices, then heat removal efficiency is improved, but electrical shorting and contamination occur
Solution Approach 1:
The assembly is divided into separate zones: a coolant-exposed zone (heat sink, coolant cavity) and a protected zone (electronic device). The dielectric plate creates a physical segmentation that allows the coolant to contact heat-generating components while preventing contact with sensitive electronics, resolving the contradiction between efficient cooling and electrical protection.
Solution Approach 2:
A dielectric plate serves as an intermediary barrier between the electrically conductive coolant and the electronic device. This intermediate component allows thermal energy to be managed (through the heat sink and coolant system) while blocking electrical conduction paths, enabling both efficient heat removal and electrical isolation.
2Temperature
If the electronic device is directly exposed to coolant for cooling, then thermal management is improved, but contamination and operational interference occur
Solution Approach 1:
The system segments the cooling function from the electronic device by introducing a heat sink as an intermediate heat-exchange component. The coolant cools the heat sink externally, which then conducts heat away from the device through a dielectric barrier, preventing direct coolant-device contact while maintaining effective thermal management.
Solution Approach 2:
The heat sink and dielectric plate combination acts as a mediator that enables thermal coupling between the electronic device and coolant system while providing contamination protection. This intermediate structure allows heat transfer without direct fluid contact, eliminating contamination risks.
3Reliability
If a seal is formed to isolate the electronic device from coolant, then electrical reliability is improved, but thermal resistance increases
Solution Approach 1:
A thin dielectric plate is used as the sealing barrier. The thin-film approach provides adequate electrical isolation while minimizing thermal resistance. The plate's thin geometry allows heat to conduct through it efficiently while still providing sufficient dielectric strength to prevent electrical breakdown from the conductive coolant.
Solution Approach 2:
The assembly uses composite material strategies: the dielectric plate provides electrical isolation properties, while the metal heat sink provides high thermal conductivity. This composite structure achieves both electrical reliability and low thermal resistance by combining materials with complementary properties in a functionally optimized arrangement.
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 assembly effectively prevents electrical shorting and contamination, improving the reliability and power dissipation efficiency of power electronics, with a demonstrated thermal resistance of 0.11° C./W, outperforming existing solutions like the Viper assembly from Delphi Inc. with a rating of 0.15° C./W.
Implementation Method 1
The sleeve is further configured to be attached to the first outer surface and the second outer surface in a manner effective to form a seal and thereby isolate the electronic device from the coolant
Implementation Method 2
The first dielectric plate defines a first inner surface that is attached to the first planar side and a first outer surface opposite the first inner surface. The first outer surface is metalized
Implementation Method 3
The cavity is configured to contain coolant within the cavity between the inlet and the outlet
Implementation Method 4
The housing is configured to define an inlet, an outlet, and a cavity configured to contain coolant within the cavity between the inlet and the outlet
Data Source
AI summary
A liquid cooled power electronics assembly configured to use electrically conductive coolant to cool power electronic devices that uses dielectric plates sealed with a metal sleeve around the perimeter of the dielectric plates to form a device assembly. The configuration allows for more direct contact between the electronic device and the coolant, while protecting the electronic device from contact with potentially electrically conductive coolant. Material used to form the dielectric plates and the housing are selected to have similar coefficients of thermal expansion (CTE) so that the reliability of the seals is maximized.