Current Transformer Core Assembly for Stable Output Voltage
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Solution Overview
Problem
Current transformers used in AC equipment face challenges in accurately detecting current values and adjusting output voltages due to issues like magnetic saturation, leakage flux, and thermal expansion, leading to insufficient temperature characteristics and large voltage tolerance.
Innovation Solution
The current transformer design incorporates E-type and I-type cores made of electromagnetic steel sheets, where the I-type core is bonded to the E-type core to form a single-piece core component. This design allows for adjustable gaps between core components, enabling high-precision adjustment of output voltage and reducing tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If E-type cores and I-type cores are alternately stacked to reduce leakage flux and improve magnetic efficiency, then the magnetic efficiency is increased and secondary output voltage stability is improved, but gaps form between junction surfaces causing variation in secondary output voltage and poor temperature characteristics
Solution Approach 1:
The patent merges the E-type core and I-type core into a single integrated core structure where the I-type core is positioned within the window of the E-type core. This integration eliminates the gaps that form between separately stacked cores, thereby reducing variation in secondary output voltage and improving temperature characteristics while maintaining the benefits of reduced leakage flux.
2Stability of the object's composition
If resin or varnish is used to fix E-type and I-type cores together, then the cores are secured in position, but thermal expansion and contraction of the resin or varnish causes variation in secondary output voltage
Solution Approach 1:
The patent extracts and eliminates the resin or varnish bonding material from the core assembly. By integrating the E-type and I-type cores into a single piece structure without requiring external bonding agents, the invention removes the source of thermal expansion and contraction issues, thereby improving temperature characteristics while maintaining core positioning stability through precise mechanical fitting.
3Ease of manufacture
If I-type cores are removed from the stacking structure, then manufacturing is simplified, but leakage flux increases between leg tips causing faster magnetic saturation and larger voltage drop
Solution Approach 1:
The patent combines the E-type core and I-type core into a single integrated structure where the I-type core is positioned within the E-type core's window. This merging maintains the magnetic circuit continuity that prevents leakage flux and magnetic saturation, while the integrated design actually simplifies manufacturing by reducing the number of separate stacking operations required.
4Reliability
If the core size is increased to prevent magnetic saturation at higher currents, then magnetic saturation resistance is improved, but device volume increases
Solution Approach 1:
The patent applies local quality optimization by strategically positioning the I-type core within the window of the E-type core to create a concentrated magnetic path. This localized magnetic circuit design improves magnetic saturation resistance by optimizing flux distribution in critical areas, thereby maintaining reliability without requiring a proportional increase in overall core volume.
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 achieves excellent temperature characteristics and allows for precise adjustment of output voltage with minimal tolerance, improving the accuracy and reliability of current detection and control in AC equipment.
Implementation Method 1
the power supply commercial frequency of the instruments is energized to the primary coil. When the current in the primary coil changes, the magnetic field in the secondary coil changes through a magnetic circuit
Implementation Method 2
the magnetic field in the secondary coil changes through a magnetic circuit, creating a potential difference at both ends of the current-sensing resistor in the secondary coil
Data Source
AI summary
The present invention provides a current transformer having excellent temperature characteristics and realizing high-precision adjustment of the output voltage via gap adjustment and small tolerance, and a method for manufacturing the same. The core component for current transformers of the present invention, comprises an E-type core 40 formed of an electromagnetic steel sheet and having three legs 41, 42, 41 extending substantially parallel to each other and a connecting part 43 connected at each end of the legs, and an I-type core 50 formed of an electromagnetic steel sheet and having the same length as the connecting portion, the I-type core being placed on and bonded to the connecting part of the E-type core to form a single-piece core component.