Bridge-Subunit Power Module for High Current Thermal Stress Relief
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Solution Overview
Problem
The existing power modules in electric vehicles face damage from thermal stress due to the mismatch in thermal expansion coefficients between substrates and metal plates, which cannot handle increasing current demands.
Innovation Solution
A power module design incorporating a bridge main unit with independent bridge subunits on substrates with low thermal expansion coefficients, allowing for efficient transmission of current and control signals while reducing thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large-area metal plate is used instead of wire to bear high current, then the current bearing capacity is improved, but the thermal expansion coefficient mismatch with the main substrate increases, causing damage under thermal stress
Solution Approach 1:
The patent introduces a bridge main unit as an intermediary component between the main substrate and the metal plate. This bridge main unit has a thermal expansion coefficient that matches the main substrate, acting as a mediator that transfers the mechanical load and thermal expansion compatibility from the metal plate to the substrate, thereby preventing thermal stress damage while maintaining high current bearing capacity
Solution Approach 2:
The patent employs a composite structure consisting of the main substrate, bridge main unit, and metal plate. Each component is selected with specific material properties: the main substrate provides structural support, the bridge main unit provides thermal expansion compatibility, and the metal plate provides high current bearing capacity. This composite approach allows the system to simultaneously achieve thermal stress resistance and high current capability
2Strength
If wire bonding is used to connect main substrates, then the substrate structure is maintained, but the current bearing capacity is insufficient for high current applications
Solution Approach 1:
The bridge main unit serves as an intermediary that replaces the wire bonding connection method. Instead of using thin wires to connect substrates, the bridge main unit provides a robust mechanical and electrical connection that can handle high currents while maintaining the substrate structure integrity
Solution Approach 2:
The patent merges the functions of electrical connection and mechanical support into the bridge main unit. This single component simultaneously provides electrical connectivity for high current transmission and structural support for the metal plate, eliminating the need for separate wire bonding and simplifying the overall connection structure
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 enables the power module to handle high current signals without damage from thermal stress, ensuring reliable operation and signal transmission.
Implementation Method 1
The first conducting region of the at least one first bridge subunit is connected between the first output terminals of the first switches and the second input terminals of the second switches, so as to transmit current signals between the first power input terminal, the first switches, the second switches, and the second power input terminal
Implementation Method 2
The second conducting regions of the at least one first bridge subunit and the at least one second bridge subunit are connected to the first control terminals of the first switches and the second control terminals of the second switches, so as to transmit control signals of the first switches and the second switches
Implementation Method 3
Compared with the shell, the main substrate has a lower thermal expansion coefficient. As a result, implementing the switch circuit by using only one main substrate may damage the main substrate under impact of a thermal stress
Data Source
AI summary
A power module includes two power input terminals, two main substrates, a plurality of first switches, a plurality of second switches, and a bridge main unit. The bridge main unit is across the two main substrates, and includes a first bridge subunit and a second bridge subunit. Each of the first bridge subunit and the second bridge subunit includes a first conducting region on a bottom surface, and a second conducting region and a third conducting region on a top surface. The first conducting region transmits a current signal of a current path of a switch circuit formed by the power input terminals, the first switches, and the second switches. The second conducting region is connected to the control terminals of the first switches and the second switches. The third conducting region is connected to the output terminals of the first switches and the second switches.