Low-Loss Ni-Cu-Zn Ferrite for High-Frequency DC/DC Converters
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Solution Overview
Problem
Current ferrites used in inductors for DC/DC converters experience high core loss at high frequencies and instability under stress and temperature variations, which affects the efficiency and stability of power conversion.
Innovation Solution
A low-loss Ni-Cu-Zn ferrite composition with specific mole percentages of Fe2O3, ZnO, CuO, SnO2, and Mn3O4, sintered at temperatures below the melting point of Ag, achieving reduced core loss and stability across a wide temperature range and under stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switching frequency is increased to suppress output voltage ripple, then filtering effectiveness is improved, but core loss of ferrite increases leading to reduced conversion efficiency
Solution Approach 1:
The patent changes the chemical composition parameters of ferrite by adding specific amounts of Mn (0.05-2% by mass as Mn3O4) and Sn (0.1-2% by mass as SnO2) along with controlled Fe2O3 content (47.1-49.3% by mol). This compositional parameter change reduces core loss at high frequencies (2 MHz or more) while maintaining the ferrite's ability to function effectively as a magnetic core in inductors for high-frequency DC/DC converters.
2Loss of energy
If ferrite composition is optimized for low loss, then conversion efficiency is improved, but stability under stress and temperature variation deteriorates
Solution Approach 1:
The patent creates a composite ferrite material combining multiple metal oxides (Fe2O3, ZnO, CuO, Mn3O4, SnO2) in specific proportions. This composite composition achieves both low core loss at high frequencies and improved stability under stress and temperature variation, resolving the contradiction between loss reduction and reliability maintenance.
Solution Approach 2:
The patent optimizes the compositional parameters within specific ranges: Fe2O3 (47.1-49.3% by mol), ZnO (20-26% by mol), CuO (6-14% by mol), Mn3O4 (0.05-2% by mass), and SnO2 (0.1-2% by mass). These controlled parameter changes ensure both low core loss and stable characteristics under various operating conditions including stress and temperature variations.
3Use of energy by stationary object
If sintering temperature is reduced, then manufacturing cost and energy consumption are decreased, but density and magnetic properties deteriorate
Solution Approach 1:
The patent modifies the chemical composition parameters by incorporating Mn and Sn as sintering aids, which lower the sintering temperature required to achieve adequate density and magnetic properties. This compositional parameter change enables energy-efficient sintering while maintaining manufacturing precision of magnetic properties.
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 ferrite exhibits core loss of 2700 kW/m3 or less at 2 MHz and 430 kW/m3 or less at 5 MHz, with saturation magnetic flux density of 390 mT, maintaining stability and low loss even under stress and temperature changes.
Implementation Method 1
The core loss of ferrite is determined by hysteresis loss, eddy current loss and residual loss. It is known that these losses depend on the magnetic properties (coercivity, saturation magnetization, magnetic domain wall resonance, etc.), crystal grain size, resistivity, etc. of ferrite.
Implementation Method 2
The core loss of ferrite is determined by hysteresis loss, eddy current loss and residual loss.
Implementation Method 3
The core loss of ferrite is determined by hysteresis loss, eddy current loss and residual loss. It is known that these losses depend on the magnetic properties (coercivity, saturation magnetization, magnetic domain wall resonance, etc.), crystal grain size, resistivity, etc. of ferrite.
Data Source
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AI summary
Low-loss ferrite comprising 100% by mass of main components comprising 47.1-49.3% by mol of Fe2O3, 20-26% by mol of ZnO, and 6-14% by mol of CuO, the balance being NiO, and 0.1-2% by mass (as SnO2) of Sn and 0.05-2% by mass (as Mn3O4) of Mn, and having an average crystal grain size of 0.5-3 µm.