Subsea Power Module Epoxy Encapsulation for High Pressure
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Solution Overview
Problem
High voltage power modules with silicone gel encapsulation fail in subsea applications due to gel dissolution in dielectric fluids, and epoxy enclosures crack under high pressure and thermal stress, making them unsuitable for high pressure subsea environments.
Innovation Solution
A high voltage power electronics module with an epoxy encapsulation structure having a specific mechanical and thermal profile, including an elastic modulus of 1-20 GPa and a coefficient of thermal expansion less than 20 ppm/K, filled with at least 75% filler material, designed with rounded corners and inclined lines to reduce stress and ensure compatibility with dielectric fluids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If silicone gel encapsulation is used, then mechanical deformability is improved, but reliability deteriorates due to gel dissolution in dielectric fluids
Solution Approach 1:
The patent changes the material parameters of the encapsulation from silicone gel to a specially formulated epoxy compound with specific mechanical properties (elastic modulus 1-20 GPa, coefficient of thermal expansion <20 ppm/K). This epoxy is specifically selected to be chemically compatible with dielectric fluids while maintaining adequate mechanical deformability under high pressure, thus resolving the contradiction between adaptability and reliability.
2Reliability
If general epoxy encapsulation is used, then compatibility with dielectric fluids is improved, but strength deteriorates due to stress concentrations under high pressure
Solution Approach 1:
The patent precisely controls the elastic modulus parameter of the epoxy encapsulation to be within 1-20 GPa range. This parameter optimization allows the epoxy to be sufficiently compliant to avoid stress concentration and cracking under high hydrostatic pressure, while maintaining adequate strength and chemical compatibility with dielectric fluids.
Solution Approach 2:
The patent employs an epoxy compound containing filler materials (at least 75% by weight) to create a composite encapsulation structure. This composite formulation enhances the mechanical properties and stress distribution characteristics of the epoxy, preventing cracking while maintaining dielectric fluid compatibility.
3Power
If high voltage power module dimensions are increased, then power handling capability is improved, but stress concentration worsens under high pressure
Solution Approach 1:
The patent optimizes the elastic modulus parameter of the epoxy encapsulation to compensate for the increased stress concentration in larger high voltage modules. The controlled stiffness of the epoxy (1-20 GPa) allows it to distribute hydrostatic pressure more uniformly across the larger module structure, preventing stress concentration at interfaces even as module dimensions increase for higher power capability.
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 module withstands high hydrostatic pressures and temperatures, preventing cracking and maintaining compatibility with dielectric fluids, enabling reliable operation in subsea environments.
Implementation Method 1
the encapsulation structure is an epoxy having an elastic modulus in a range of 1 to 20 Giga Pascal, GPa, at room temperature
Implementation Method 2
a coefficient of thermal expansion less than 20 ppm/K
Implementation Method 3
In any cross-section through the encapsulation structure, perpendicular to a plane defined by a surface of the baseplate on which the power semiconductor chip is arranged, the encapsulation structure has rounded inner corners
Data Source
Figure 1~2
AI summary
The present disclosure relates to a high voltage power electronics module (1) for subsea applications. The power electronics module (1) comprises: a baseplate (3), a power semiconductor chip (7) arranged on the baseplate (3), and an encapsulation structure (5) arranged on the baseplate (3) and configured to encapsulate the power semiconductor chip (7), wherein the encapsulation structure (5) is an epoxy having an elastic modulus less in a range of 1 to 20 Giga Pascal, GPa, at room temperature and a coefficient of thermal expansion less than 20 ppm/K.