Modular Capacitor Bus for DC Bus Thermal Management
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Solution Overview
Problem
As motor drive ratings increase, the number of DC bus capacitors required also increases, leading to larger enclosures and increased space consumption, which is inefficient and results in higher operating temperatures and reduced component life due to heat buildup.
Innovation Solution
A modular capacitor bus with a laminated structure is mounted to the DC bus, allowing capacitors to be arranged in parallel and spaced apart, enabling a more densely populated power structure with improved airflow for heat dissipation and reduced operating temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If more DC bus capacitors are used to handle higher voltage ratings, then the capacitance and voltage handling capability are improved, but the space consumption and enclosure size increase
Solution Approach 1:
The capacitor bus is nested within the DC bus structure, with capacitors mounted on the capacitor bus that is itself mounted to the DC bus. This nested arrangement allows multiple capacitors to be integrated into the existing bus structure without requiring additional external space, effectively nesting the capacitor assembly within the DC bus volume.
Solution Approach 2:
The capacitor bus extends in parallel spaced-apart planes from the DC bus, utilizing the third dimension (depth) rather than only increasing surface area. By arranging capacitors in parallel planes and using vertical stacking with the DC bus, the design transitions from a two-dimensional surface mounting approach to a three-dimensional integrated structure, increasing capacitance without proportionally increasing enclosure footprint.
2Ease of manufacture
If capacitors are mounted directly to the DC bus, then the assembly is simple, but heat buildup increases and component life decreases
Solution Approach 1:
The bus structure is segmented into two separate components: the DC bus and the capacitor bus. This segmentation allows the capacitors to be mounted on the capacitor bus with spacing between them and the main DC bus, creating thermal separation that reduces heat buildup while maintaining assembly simplicity through modular construction.
Solution Approach 2:
The capacitor bus acts as an intermediary structure between the DC bus and the capacitors. This intermediate layer provides thermal management by spacing capacitors away from the main DC bus while maintaining electrical connections, thereby reducing direct heat transfer and improving component longevity without complicating the assembly process.
3Quantity of substance
If the surface area of the DC bus is increased to accommodate more capacitors, then more capacitors can be mounted, but the DC bus size and enclosure volume increase
Solution Approach 1:
Instead of increasing the surface area of the DC bus in two dimensions, the design utilizes the third dimension by extending the capacitor bus in parallel spaced-apart planes. This allows multiple capacitors to be mounted vertically and in stacked arrangements, increasing capacitor quantity without proportionally increasing the DC bus surface area or enclosure footprint.
Solution Approach 2:
The capacitor bus is nested within the overall DC bus assembly, with capacitors integrated into the bus structure rather than mounted externally. This nested configuration allows multiple capacitors to be packed into the existing bus volume, increasing capacitor density without requiring additional DC bus surface area or enclosure space.
Data Source
AI summary
An apparatus and method for mounting additional components, such as capacitors, to a DC bus of a motor drive. In one aspect, a motor drive includes an enclosure defining an interior, an input for receiving input electrical power from a power source, an output for providing output electrical power to a load, an intermediate DC circuit including a DC bus located in the interior of the enclosure, and a modular capacitor bus electrically coupled with the intermediate DC circuit, the modular capacitor bus including at least one capacitor mounted thereto. The modular capacitor bus is mountable as a unit to the DC bus.