Transformer Shielding Winding Noise Cancellation
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Solution Overview
Problem
Transformers in switching power supplies generate electromagnetic noise due to common-mode interference, which is difficult to mitigate without increasing size and cost by adding shielding layers, and existing methods struggle to balance noise cancellation between primary and secondary windings.
Innovation Solution
Incorporating a shielding winding part between the primary and secondary winding units within a magnetic core, where the shielding winding is electrically connected to a static node, allowing for noise cancellation without additional shielding layers, thereby reducing the transformer's size and leakage inductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If shielding layers are inserted between the primary winding and the secondary winding, then the common-mode noise is attenuated, but the leakage inductance of the transformer is magnified and the size increases
Solution Approach 1:
The patent merges the shielding function with the existing primary winding structure by dividing it into first and second primary windings that are interleaved with the secondary winding. This integration eliminates the need for separate shielding layers while maintaining noise attenuation functionality.
Solution Approach 2:
The primary winding is segmented into first and second primary windings that are positioned alternately with the secondary winding. This segmentation creates multiple coupling capacitance paths that help attenuate common-mode noise without requiring additional shielding materials.
2Object-affected harmful factors
If shielding layers are inserted between the primary winding and the secondary winding, then the common-mode noise is attenuated, but the cost increases
Solution Approach 1:
The shielding function is merged into the primary winding structure itself, eliminating the need for separate shielding materials and reducing manufacturing costs. The first and second primary windings serve both as functional windings and as noise shielding structures.
Solution Approach 2:
The first and second primary windings perform multiple functions: they provide the necessary electromagnetic coupling for power transfer and simultaneously act as shielding structures to attenuate common-mode noise, reducing the need for additional components.
3Object-affected harmful factors
If the distance between the primary winding and the secondary winding is increased, then the coupling capacitance is reduced, but the leakage inductance is magnified
Solution Approach 1:
The windings are segmented into first and second primary windings that are interleaved with the secondary winding, creating multiple close-proximity coupling paths. This maintains sufficient coupling capacitance for noise attenuation while preventing excessive leakage inductance.
Solution Approach 2:
Instead of increasing distance in one dimension, the patent uses interleaved winding arrangements that create multiple coupling paths in different spatial dimensions, maintaining effective capacitance coupling while managing leakage inductance.
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 design effectively lowers noise without additional shielding, reducing the transformer's size and cost while minimizing leakage inductance, achieving noise cancellation and meeting regulatory standards.
Implementation Method 1
the first shielding part is disposed between the first input primary winding part and the secondary winding part, and the primary winding unit and the secondary winding unit are assembled in the magnetic core
Data Source
AI summary
A transformer includes a primary winding unit, a secondary winding unit and a magnetic core. The primary winding unit includes a first input primary winding part and a first shielding winding part. The first input primary winding part is electrically connected to at least one switch component, and the first input primary winding part is electrically connected to the first shielding winding part. The secondary winding unit is inductively coupled to the primary winding unit, and the first shielding part is disposed between the first input primary winding part and the secondary winding part. Then, the primary winding unit and the secondary winding unit are assembled to the magnetic core.