Traction Inverter Bus Bar Layout for Low Stray Inductance
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Solution Overview
Problem
Existing traction inverters for electric and hybrid vehicles face issues with increased stray inductance due to separated bus bars, leading to voltage spikes and higher costs for power cards.
Innovation Solution
The solution involves stacking capacitors with positive and negative leads and using bus bars with pass-through slots to reduce stray inductance, allowing for lower capacity power cards and reduced inverter size and mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bus positive and negative bus bars are separated between the positive and negative terminals of the capacitor, then the capacitor can filter electric power effectively, but the stray inductance of the inverter circuitry increases
Solution Approach 1:
The patent merges the positive and negative bus bars into a single integrated structure that connects to both terminals of the capacitor simultaneously. This combined bus bar structure reduces the separation distance between positive and negative connections, thereby minimizing stray inductance while maintaining effective power filtering capability.
Solution Approach 2:
The patent transitions from a linear separation of bus bars to a three-dimensional integrated configuration where the bus bar structure extends in multiple dimensions to connect to both capacitor terminals. This dimensional change allows simultaneous connection to positive and negative terminals while keeping the overall structure compact and low-inductance.
2Device complexity
If bus bars are separated to connect to capacitor terminals, then the capacitor can be integrated into the inverter, but the inverter size and mass increase
Solution Approach 1:
The patent combines the bus bar structure with the capacitor mounting structure into a single integrated component. The bus bar serves dual functions as both the electrical connector and the mechanical mounting element, eliminating the need for separate mounting brackets and fasteners, thereby reducing overall inverter mass.
Solution Approach 2:
The bus bar structure is designed to perform multiple functions simultaneously: electrical connection to capacitor terminals, mechanical support for the capacitor, and structural integration with the inverter housing. This multi-functionality reduces the number of separate components needed, decreasing overall inverter mass and complexity.
3Reliability
If power cards are designed with components that tolerate voltage spikes, then the inverter can operate reliably, but the financial expense of the power cards increases
Solution Approach 1:
The patent converts the potentially harmful voltage spikes into a design advantage by using the bus bar structure to actively suppress spike generation at the source. The low-inductance design prevents voltage spikes from occurring in the first place, eliminating the need for expensive spike-tolerant components and converting a harmful effect into a design feature.
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 approach decreases stray inductance and resistance, enabling the use of lower voltage-rated power modules, reducing financial and mass expenses, and improving vibration durability and switching efficiency.
Implementation Method 1
a first bus bar including pass through slots for the positive leads and negative leads of each of the plurality of stacked capacitors; and a second bus bar including pass through slots for solely the positive leads or for solely negative leads
Implementation Method 2
The capacitance of the capacitor and the power requirements of the capacitor may result in a separation of bus positive and negative bus bars between the positive and negative terminals of the capacitor. The separation in bus bars may increase stray inductance of the inverter circuitry
Data Source
AI summary
Systems and methods for constructing a traction inverter of a vehicle are described. The traction inverter includes a positive bus bar and a negative bus bar that couple a capacitor and to a plurality of switches. The capacitor is formed from a plurality of individual capacitors that are stacked together.