Current Transformer Core Gap Tuning for Stable Output Voltage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current transformers face issues with magnetic saturation and secondary output voltage variations due to thermal expansion and contraction, leading to inaccurate current detection and larger tolerances, which affect the operation of electrical devices.
Innovation Solution
A current transformer design featuring a bobbin with a primary and secondary coil, and core components comprising E-type and I-type cores formed by press-punching electromagnetic steel sheets, where the cores are bonded to form a single-piece structure with adjustable gaps between them, allowing precise output voltage adjustment and improved temperature stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If E-type cores and I-type cores are alternately stacked to reduce leakage flux and increase magnetic efficiency, then the magnetic efficiency is improved, but the secondary output voltage varies due to gap variation and thermal expansion/contraction of resin or varnish
Solution Approach 1:
The core is divided into multiple E-type cores and I-type cores that are alternately stacked. Each core type is segmented to create a modular structure that reduces leakage flux while maintaining magnetic efficiency. The segmentation allows for precise control of gaps between cores.
Solution Approach 2:
The patent changes the physical parameters of the core structure by controlling the gap dimensions between E-type and I-type cores. By precisely adjusting gap parameters (e.g., gap width, spacing), the invention optimizes magnetic efficiency while maintaining stable secondary output voltage characteristics.
2Stability of the object's composition
If resin or varnish is used to fix E-type core and I-type core together, then the structural stability is improved, but the secondary output voltage varies due to thermal expansion and contraction
Solution Approach 1:
The patent changes the material parameters by selecting resin or varnish with specific thermal expansion coefficients that match the core materials. This parameter optimization minimizes the effect of thermal expansion and contraction on the secondary output voltage while maintaining structural stability.
Solution Approach 2:
The invention uses composite material structures where resin or varnish is combined with E-type and I-type cores. The composite structure is designed to have matched thermal properties, reducing differential thermal expansion and maintaining stable electrical characteristics across temperature variations.
3Ease of manufacture
If I-type cores are removed and only E-type cores are used with overlapping leg tips, then the manufacturing is simplified, but the leakage flux increases causing faster magnetic saturation
Solution Approach 1:
The patent segments the core into alternating E-type and I-type configurations, which creates a more effective magnetic path structure. This segmentation reduces leakage flux between core legs while maintaining manufacturing feasibility through standardized core components.
Solution Approach 2:
The I-type cores act as intermediaries between E-type cores, providing magnetic coupling that reduces leakage flux. The I-type cores mediate the magnetic field distribution, preventing direct leakage that would occur with only overlapping E-type leg tips.
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 design achieves high-precision output voltage adjustment with minimal tolerance, enhancing the accuracy of current detection and reducing thermal expansion effects, thereby optimizing electrical device operation within circuit breaker limits.
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
Figure 1~2
Figure 3(a)~4
Figure 5(a)~6
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.