Parallel Ceramic Capacitor DC-Link for High Current Ripple
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Solution Overview
Problem
Ceramic capacitors used in DC-link arrangements face limitations in high current applications due to mechanical stress from vibrations, which can lead to short-circuits, and they struggle to handle high capacitance requirements, necessitating a solution to evenly distribute current and prevent overloading.
Innovation Solution
A capacitor DC-link arrangement with multiple ceramic capacitor elements connected in parallel, ensuring equal resistance paths and using strengthening bus bars to enhance mechanical stability, allowing for even current distribution and preventing overloading, while optionally incorporating electrolytic capacitors for higher capacitance needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple ceramic capacitor elements are connected in parallel to handle high current applications, then current handling capability is improved, but current distribution becomes uneven causing overloading of certain capacitor elements
Solution Approach 1:
The invention divides the DC-link arrangement into multiple identical current paths, each containing one or more ceramic capacitor elements. By segmenting the current distribution into equal paths with matched impedance, the current automatically distributes evenly across all capacitor elements, preventing overloading while maintaining high current handling capability through parallel connection.
Solution Approach 2:
The invention intentionally introduces asymmetry in the form of balancing resistors or impedance matching elements in series with each capacitor element or current path. These asymmetric elements are designed to equalize the total impedance of each path, thereby forcing symmetric current distribution despite the parallel asymmetric capacitor connections.
2Power
If ceramic capacitors are used in high vibration environments, then high current ripple handling is improved, but mechanical damage and short-circuits occur due to vibration stress
Solution Approach 1:
The invention merges multiple ceramic capacitor elements into a unified parallel configuration with shared mounting structures and common terminals. This merging approach distributes vibration stresses across multiple connection points and provides mechanical redundancy, where the failure of one capacitor does not necessarily lead to system failure, thereby improving overall mechanical stability in high vibration environments.
Solution Approach 2:
The invention incorporates mechanical cushioning elements, damping structures, or compliant mounting arrangements before the vibration stresses can cause damage to the ceramic capacitors. These protective features are built into the design from the beginning to absorb and dissipate vibration energy, preventing mechanical damage and short-circuits while maintaining the capacitors' ability to handle high current ripple.
3Quantity of substance
If high capacitance is required in high current applications, then energy storage capability is improved, but capacitor size and complexity increase
Solution Approach 1:
The invention achieves high capacitance by segmenting the total capacitance requirement into multiple smaller ceramic capacitor elements connected in parallel. Each element contributes to the total capacitance while maintaining manageable individual sizes. This segmentation approach simplifies the overall arrangement by using standardized, off-the-shelf capacitor components rather than requiring a single large, complex capacitor.
Solution Approach 2:
The invention combines multiple ceramic capacitor elements with individual capacitances into a parallel configuration to achieve the required total capacitance. This merging of multiple simple components creates a compact, modular arrangement that is easier to design, manufacture, and maintain compared to using fewer larger capacitors, thereby reducing overall device complexity while meeting high capacitance requirements.
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 ensures homogeneous loading of ceramic capacitors, prevents overloading and mechanical damage from vibrations, and allows for compact packaging, effectively managing high current ripple applications and increasing the reliability of the capacitor bank.
Implementation Method 1
Capacitor DC link arrangements are usually used in power conversion systems in order to balance instantaneous power differences between an input source and an output load and in order to minimize voltage variations
Implementation Method 2
each capacitor current path has the same resistance such that as a consequence of this current and/or electric charge is evenly distributed over all ceramic capacitor elements
Data Source
Figure 1~2
Figure 3~4
AI summary
The present invention provides a capacitor DC-link arrangement, in particular for high current ripple applications. The capacitor DC-link arrangement comprises a substrate such as a PCB-based substrate, a first terminal and a second terminal which are both arranged on the substrate, a plurality of ceramic capacitor elements, wherein: each of the ceramic capacitor elements is connected as well to the first terminal and the second terminal, the plurality of ceramic capacitor elements are connected in parallel, and the ceramic capacitor elements are arranged and connected in a similar current path and in particular in the same resistance current path.