Offset-Substrate Inverter Power Module for EV Thermal Management
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Solution Overview
Problem
Inverters for electric vehicles face challenges with heat management and thermal characteristics due to the generation of heat by power modules, which can compromise their operation and efficiency.
Innovation Solution
A power module design incorporating a first and second substrate with electrically conductive spacers and a flex circuit to manage thermal characteristics and maintain electrical connectivity, using materials like silicon nitride and metal for improved heat dissipation and insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power modules are used to generate high power in inverter, then power output is improved, but heat generation increases causing thermal management issues
Solution Approach 1:
The power module is divided into multiple semiconductor dies (e.g., IGBTs and diodes) mounted on separate substrates, allowing heat to be distributed across multiple mounting points and thermal paths rather than concentrated in a single location, thereby improving heat dissipation efficiency while maintaining high power output capability
Solution Approach 2:
Thermal interface materials and heat sinks are introduced as intermediary components between the semiconductor dies and the external environment. These intermediaries facilitate efficient heat transfer from the high-power generating components to the cooling system, enabling sustained high power operation without excessive temperature rise
2Volume of moving object
If substrates are placed close together to reduce module size, then volume is reduced, but thermal insulation and heat dissipation become more difficult
Solution Approach 1:
The patent utilizes three-dimensional substrate stacking arrangements where substrates are positioned at different vertical levels with controlled spacing. This dimensional approach allows heat to dissipate through multiple directions (horizontally and vertically) rather than being constrained to a single plane, enabling effective thermal management in a compact volume
Solution Approach 2:
The substrate structure employs composite materials with different thermal conductivities in different directions and layers. Insulating materials are used between adjacent substrates to prevent heat transfer in unwanted directions, while thermally conductive pathways are provided through heat sinks and thermal interface materials, creating a composite thermal management system that fits within reduced module volume
3Reliability
If electrically conductive spacers are used to connect substrates, then electrical connectivity is improved, but thermal conduction may increase causing heat transfer issues
Solution Approach 1:
The spacer structure is designed with non-uniform electrical conductivity distribution: regions requiring electrical connection (such as contact points with substrates) have high electrical conductivity, while intermediate regions have reduced electrical conductivity to minimize parasitic inductance and unwanted electrical coupling. This local quality variation allows the spacers to provide necessary electrical connectivity while controlling thermal and electrical interference
Solution Approach 2:
The electrical and thermal parameters of the spacers are optimized by changing their material composition, geometry, and cross-sectional area along their length. By varying these parameters, the spacers achieve the desired electrical connectivity for signal and power transmission while limiting excessive thermal conduction that would cause heat transfer between substrates
4Temperature
If insulation between substrates is increased to prevent heat transfer, then thermal management is improved, but electrical connectivity and signal transmission are compromised
Solution Approach 1:
Electrically conductive spacers serve as intermediary components that bridge the insulated substrate gap. These spacers provide controlled electrical connection points while the bulk insulation material between substrates maintains thermal isolation. The intermediary spacers enable necessary signal and power transmission without compromising the overall thermal management strategy
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 design enhances thermal management and electrical performance by maintaining efficient heat dissipation and insulation, ensuring stable operation of the inverter and motor drive.
Implementation Method 1
an electrically conductive spacer connecting the first substrate to the second substrate
Implementation Method 2
the middle section includes a ceramic, and the outer surface and the inner surface of the first substrate includes a metal
Data Source
AI summary
A power module includes: a first substrate having an outer surface and an inner surface, the first substrate extending from a first longitudinal end toward a second longitudinal end; a power switch including a semiconductor die, the power switch being coupled to the inner surface of the first substrate; a second substrate having an outer surface and an inner surface, the power switch being coupled to the inner surface of the second substrate, the second substrate extending from a first longitudinal end toward a second longitudinal end, wherein the first longitudinal end of the first substrate is longitudinally offset from the first longitudinal end of the second substrate; a first electrically conductive spacer coupled to inner surface of the first substrate and to the inner surface of the second substrate; and a flex circuit coupled to the power switch.