Metallized Film Capacitor Winding Core Heat Dissipation
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Solution Overview
Problem
Metallized film capacitors used in hybrid electric vehicles face inadequate heat dissipation due to insufficient thermal conductivity, leading to increased heat generation and reduced operational efficiency.
Innovation Solution
The design incorporates winding cores with a specific length relationship (L1 > L2, L1 + L2 < Ld, L1 ≥ Ld/2, L2 ≥ (Ld - L1)/2) and edge-surface electrodes made of high thermal conductivity materials, connected to bus bars and a metallic case, enhancing heat dissipation by acting as a heat pipe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional winding core configuration is used, then structural simplicity is maintained, but heat dissipation performance is insufficient
Solution Approach 1:
The single winding core is divided into two separate winding cores (first and second winding cores) positioned at different locations within the capacitor element. This segmentation allows heat to be dissipated from multiple locations simultaneously, improving overall heat dissipation performance while maintaining relatively simple individual core structures
Solution Approach 2:
The invention transitions from a single-point heat dissipation approach to a distributed multi-point heat dissipation approach by placing winding cores at different positions along the length of the capacitor element. This spatial distribution across different dimensions enables more effective heat removal from various regions of the capacitor
2Temperature
If winding core length is increased to improve heat dissipation, then heat dissipation performance improves, but capacitor element length increases
Solution Approach 1:
Instead of using one extremely long winding core that would extend the capacitor length significantly, the heat dissipation function is segmented into two separate winding cores of moderate length. Each core handles heat dissipation from its local region, achieving effective heat removal without requiring excessive overall length
Solution Approach 2:
The invention uses two winding cores with lengths that are sufficient for their respective heat dissipation zones but not excessively long. The combined effect of two partially-effective cores achieves better overall heat dissipation than a single core would, without the penalty of excessive length
3Power
If AC ripple current increases for higher power applications, then power handling capability improves, but heat generation increases
Solution Approach 1:
The heat dissipation function is segmented across multiple winding cores positioned at different locations, allowing heat generated from high AC ripple current to be removed from multiple points simultaneously. This distributed approach prevents heat accumulation that would occur with a single heat dissipation path
Solution Approach 2:
The winding cores act as intermediary heat transfer elements between the capacitor element and the external environment. These metallic cores conduct heat away from the capacitor element through thermal conduction, serving as a heat transfer medium that enables effective heat removal during high-power operation
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 significantly improves heat dissipation performance, reducing temperature rise by up to 6.8°C compared to conventional designs, making it suitable for high-voltage applications in harsh environments.
Implementation Method 1
Winding cores 2 and 3 are made of aluminum and therefore provide relatively high heat conduction. Generated heat is transferred to the bus bar via sprayed-metal electrodes 5 and 6 and further led to the outside
Implementation Method 2
Generated heat is transferred to the bus bar via sprayed-metal electrodes 5 and 6 and further led to the outside
Data Source
AI summary
A metallized film capacitor includes first and second winding cores disposed along a center axis, and a capacitor element wound about the center axis around the first and the second winding cores. The second winding core is apart from the first winding core. The first and second winding cores have a thermal conductivity larger than that of the dielectric film of the capacitor element. Length Ld of the capacitor element in a direction of the center axis, length L1 of the first winding core inside the capacitor element in the direction of the center axis, and length L2 of the second winding core inside the capacitor element in the direction of the center axis satisfy the relations of L1>L2, L1+L2<Ld, L1≧Ld/2, and L2≧(Ld−L1)/2. The metallized film capacitor provides the capacitor element with improved heat dissipation performance.