Composite Dielectric Material for Temperature-Stable High-Voltage Capacitors
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Solution Overview
Problem
Existing high voltage capacitors experience significant changes in capacitance due to temperature fluctuations, exceeding ±5% over their use temperature range, which is unsuitable for precise voltage sensing in complex power distribution networks.
Innovation Solution
A high voltage capacitor with a dielectric material comprising first and second dielectric fillers in an insulating polymer matrix, ensuring a capacitance variation of no more than ±0.5% from -20°C to 60°C, and a temperature coefficient of capacitance (TCC) of less than ±50 ppm, using materials like silicon dioxide and strontium titanate in a curable epoxy resin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If dielectric constant is increased to reduce capacitor size, then volume is reduced, but reliability worsens due to increased susceptibility to internal breakdown
Solution Approach 1:
The patent employs a composite dielectric structure where a thin film dielectric layer with high dielectric constant is combined with an organic solid electrolyte layer. The thin film layer provides high capacitance density for compact size, while the organic electrolyte layer acts as a protective barrier that prevents internal breakdown, thus resolving the contradiction between miniaturization and reliability.
Solution Approach 2:
The patent applies different material properties to different layers: the thin film dielectric layer provides high dielectric constant for compact size in the first layer, while the organic solid electrolyte layer provides breakdown protection and leakage current suppression in the second layer. This local differentiation of material qualities resolves the contradiction between size reduction and reliability maintenance.
2Adaptability or versatility
If operating temperature range is extended using organic solid electrolyte, then temperature adaptability is improved, but leakage current increases over time
Solution Approach 1:
The patent combines a thin film dielectric layer with an organic solid electrolyte layer to create a composite structure where the thin film provides stable electrical properties and low leakage current, while the organic electrolyte provides temperature compensation. This composite approach resolves the contradiction between extended temperature range and leakage current stability.
Solution Approach 2:
The thin film dielectric layer acts as an intermediary barrier between the anode and the organic solid electrolyte. It prevents direct contact between the electrode and organic electrolyte, thereby suppressing leakage current while allowing the organic electrolyte to perform its temperature compensation function, thus resolving the contradiction between temperature adaptability and leakage current stability.
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
The solution provides a stable capacitance and reduced TCC, enabling accurate voltage sensing in high voltage applications, meeting industry standards for breakdown strength and temperature stability.
Implementation Method 1
a first dielectric layer comprising a thin film having a dielectric constant of 30 or more
Implementation Method 2
the organic solid electrolyte has a negative temperature coefficient
Data Source
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AI summary
A high voltage capacitor for a voltage divider is described that is configured to sense an elevated voltage for medium and high voltage electrical distribution networks. The high voltage capacitor comprises a high voltage electrode, a measurement electrode, and an dielectric material disposed between the high voltage and measurement electrodes, wherein the dielectric material comprises first and second dielectric fillers disposed in an insulating polymer matrix such that the change in capacitance of the dielectric does not vary by more than +/- 0.5% in the temperature range of –30°C to 60°C and the high voltage capacitor has a withstand voltage of at least 50 kV.