Isolation Transformer Loop Switching to Reduce EMI Calibration
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Solution Overview
Problem
Existing isolation transformers suffer from significant electromagnetic interference (EMI) issues, requiring adaptations to international standards and infield calibration, which hinders commercialization and complicates application.
Innovation Solution
Incorporating at least two electrically-conductive loops placed where magnetic fields are expected, coupled with a physical electrical ground node via a switching circuit in a predefined sequence and pattern to effectively capture and redirect EMI, thereby averaging it out and improving power factor without critical node placement requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a physical electrical ground node is placed at a location within the transformer where magnetic flux and electric field are lowest, then EMI is reduced, but the placement is critical and application-dependent requiring infield calibration
Solution Approach 1:
The transformer performs self-calibration by automatically identifying optimal ground node placement locations through its control system, eliminating the need for manual infield calibration. The system services itself by adjusting the ground node position based on detected magnetic flux and electric field conditions.
Solution Approach 2:
The physical electrical ground node is made movable rather than fixed, allowing it to be dynamically repositioned to optimal locations. This dynamic capability enables the system to adapt to different operating conditions and load configurations without requiring manual recalibration.
2Object-affected harmful factors
If the physical electrical ground node placement is optimized for minimum EMI, then EMI is reduced, but the ideal position depends on load which determines internally created fields
Solution Approach 1:
The ground node position is dynamically adjusted based on detected load conditions and resulting magnetic flux patterns. The system automatically adapts its configuration to match different operating scenarios, maintaining optimal EMI reduction across varying load conditions.
Solution Approach 2:
The control system continuously monitors magnetic flux and electric field conditions resulting from different loads, and uses this feedback information to determine optimal ground node placement. This closed-loop feedback mechanism ensures adaptability to changing operational conditions.
3Object-affected harmful factors
If clean ground terminals are provided separately from normal ground terminals, then EMI is reduced, but device complexity increases
Solution Approach 1:
The movable physical electrical ground node serves multiple functions: it acts as a clean ground reference when positioned for EMI reduction, and can be repositioned to serve different operational requirements. This multi-functionality reduces the need for separate dedicated ground terminals for different purposes.
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 solution eliminates the need for international standard adaptations and infield calibration, achieving high power factors up to 0.9 and low Total Harmonic Distortion (THD) below 8%, while reducing EMI and heat, and allowing for self-calibration regardless of load balance.
Implementation Method 1
Incorporating at least two electrically-conductive loops placed where magnetic fields are expected, coupled with a physical electrical ground node via a switching circuit in a predefined sequence and pattern to effectively capture and redirect EMI
Implementation Method 2
a magnetizable core; at least one primary coil and at least one secondary coil provided around the magnetizable core
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a transformer (100e1) comprising: i) a magnetizable core (110) with respective primary and secondary coils; ii) a ground terminal (PE) for electrically connecting to an external ground terminal (999) of an electric power grid (900), and iii) a physical electrical ground node (175) placed at a location within the isolation transformer (100e1), wherein the physical electrical ground node (175) is electrically connected to the ground terminal (PE, 199). The transformer (100e1) further comprises: iv) at least two electrically-conductive loops (CL1..CL6) that are placed at different locations in the transformer (100e1) where a magnetic field may be built up during operational use, and v) a switching circuit (801) configured for sequentially, temporarily and selectively electrically coupling subsets (SS) of the electrically-conductive loops (CL1..CL6) with the physical electrical ground node (175) in accordance with a certain sequence and pattern. The invention provides for an isolation transformer that is much less susceptible to EMI without requiring any adaptation of the standards. In addition, the transformer does not require any infield adjustments or calibration.