Parallel Capacitor Bus Bar Layout for Uniform Heat Generation
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Solution Overview
Problem
Conventional power conversion devices experience variations in heat generation among multiple capacitor elements due to mismatched resonance frequencies and inductances caused by unequal current paths.
Innovation Solution
The capacitor design aligns capacitor elements in a specific direction, with the farthest element from the external terminal positioned closest to a side plate of the connecting part, allowing magnetic fluxes to cancel each other and match inductances, thereby reducing variations in heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple capacitor elements are connected in parallel to increase capacitance, then the total capacitance increases, but variations in heat generation occur due to mismatched resonance frequencies and inductances
Solution Approach 1:
The patent applies local quality by positioning capacitor elements at different distances from the external terminal according to their capacitance values. Specifically, capacitor elements with larger capacitance are positioned farther from the external terminal, while those with smaller capacitance are positioned closer. This non-uniform spatial arrangement compensates for the inherent differences in electrical characteristics, ensuring that each capacitor element experiences appropriate inductance and resonance frequency conditions, thereby reducing heat generation variations and improving overall reliability.
2Ease of manufacture
If capacitor elements are positioned at equal distances from the external terminal, then the structure is simplified and easier to manufacture, but resonance frequencies and inductances become mismatched causing unequal heat generation
Solution Approach 1:
The patent transitions from a uniform structure (equal distances) to a non-uniform structure (different distances) where each capacitor element's position is optimized according to its specific capacitance value. This local differentiation in positioning creates the necessary variation in current path lengths and inductances to match the resonant frequencies of different capacitor elements, thereby achieving uniform heat generation while maintaining relatively simple manufacturing processes.
3Quantity of substance
If capacitor elements with different capacitance values are used to achieve desired total capacitance, then the total capacitance requirement is met, but impedance and phase differences increase causing performance degradation
Solution Approach 1:
The patent uses local quality by assigning specific positions to capacitor elements based on their capacitance values. Elements with different capacitance values are positioned at different locations along the current path from the external terminal, creating a gradient arrangement. This spatial differentiation compensates for the electrical differences, ensuring that each element operates at its optimal resonance frequency, thereby minimizing impedance and phase differences across the parallel connection and improving overall system performance.
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 design effectively matches resonance frequencies and inductances across all capacitor elements, minimizing impedance and phase differences, thus reducing heat generation variations and improving overall performance.
Implementation Method 1
allowing magnetic fluxes to cancel each other and match inductances
Data Source
AI summary
A capacitor includes a plurality of capacitor elements aligned in a first direction, a first bus bar, and a second bus bar. Each of the plurality of capacitor elements includes an element body, a first electrode, and a second electrode. The first bus bar includes a first internal terminal connected to the first electrode, a first external terminal, and a first connecting part that connects the first internal terminal with the first external terminal. The first connecting part includes a side plate positioned at a side of the plurality of capacitor elements in a second direction orthogonal to the first direction. A capacitor element disposed at a position farthest from the first external terminal in the first direction among the plurality of capacitor elements is disposed at a position closest to the side plate of the first connecting part in the second direction.