Segmented Capacitor Design for SiC Power Conversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional power conversion devices using high-temperature switching elements like silicon carbide (SiC) face increased costs and size due to the need for heat-resistant capacitors, which also impair low-inductance characteristics when heat-resistant capacitors are not used.
Innovation Solution
A power conversion device design where a filter capacitor is sectioned into a first capacitor and a second capacitor with higher heat resistance, with the second capacitor connected to the semiconductor element module using a connection conductor and a busbar, allowing the first capacitor to establish an electrical connection through the busbar and connection conductor, effectively managing heat transfer and maintaining low inductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat-resistant capacitor is used to withstand higher temperatures from SiC elements, then the capacitor can operate at higher temperatures, but the cost increases
Solution Approach 1:
The capacitor is divided into two distinct parts: a first capacitor section with lower heat resistance connected to the SiC element, and a second capacitor section with higher heat resistance connected to the busbar. This segmentation allows each part to be optimized for its specific function, with only the necessary portion having heat-resistant properties, thereby reducing overall cost while maintaining operational capability at higher temperatures
Solution Approach 2:
Heat resistance is applied locally only to the second capacitor section that is in direct thermal proximity to the heat-generating SiC element, rather than making the entire capacitor heat-resistant. This localized approach reduces material costs while providing heat resistance exactly where it is needed to protect the capacitor from temperature-induced failures
2Ease of manufacture
If the distance between the switching element and capacitor is increased to avoid heat-resistant capacitors, then cost is reduced, but the low-inductance characteristics are impaired
Solution Approach 1:
The capacitor is segmented into two functional sections with different thermal characteristics. The first capacitor section can be positioned closer to the SiC element to maintain low inductance, while the second heat-resistant section provides thermal protection. This segmentation enables optimized spatial arrangement that satisfies both electrical performance (low inductance) and thermal management requirements without requiring the entire capacitor to be heat-resistant
Solution Approach 2:
The first capacitor section acts as an intermediary between the SiC element and the second capacitor section. It provides the low-inductance electrical connection path close to the switching element, while the second heat-resistant section serves as a thermal buffer. This intermediary structure allows the system to achieve both low inductance and heat management without increasing overall distance
3Temperature
If a heat-resistant capacitor is used, then the capacitor can withstand higher temperatures, but the device size increases
Solution Approach 1:
The capacitor is divided into two sections with different heat resistance levels. Only the second capacitor section requires heat-resistant construction, allowing it to be positioned closer to the heat source without requiring the entire capacitor assembly to be large and heat-resistant. This segmentation enables compact overall device size while maintaining the ability to withstand higher temperatures at the critical interface with the SiC element
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 configuration achieves low inductance between the switching element and capacitor while suppressing cost and size increases, allowing for efficient heat management without the need for high-cost heat-resistant capacitors.
Implementation Method 1
a filter capacitor (12) to accumulate therein DC power
Implementation Method 2
the second capacitor (11) is connected to the semiconductor element module (101 to 106) by using a connection conductor (16), and is electrically connected to a busbar (17) different from the connection conductor (16)
Implementation Method 3
the second capacitor (11) having a higher heat resistance than the first capacitor (12)
Data Source
AI summary
A power conversion device includes a filter capacitor to accumulate therein DC power, and an element unit including a semiconductor element module to perform a switching operation for converting the DC power accumulated in the filter capacitor into AC power. The filter capacitor and the element unit are disposed in the same casing. A heat-resistant capacitor having a higher heat resistance than the filter capacitor is connected to the element portion by using a connection conductor, and is also connected to a busbar different from the connection conductor. An electrical connection between the filter capacitor and the element unit is established through the busbar, the connection conductor, and the heat-resistant capacitor.