Isolation Transformer Coupling Winding Shield Terminal
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Solution Overview
Problem
Isolation transformers face issues with interwinding capacitance, which allows unwanted currents to flow through the transformer, potentially disrupting or damaging circuitry due to internal capacitances that compromise galvanic isolation.
Innovation Solution
Incorporating a coupling winding with shield terminals electrically coupled to ground to direct common mode currents to ground, and using additional secondary coils connected to a DC source for further isolation, reducing interwinding capacitance and preventing damage to circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transformer is used to provide galvanic isolation, then isolation between power source and load is achieved, but interwinding capacitance allows current to flow through the transformer
Solution Approach 1:
A coupling winding is introduced as an intermediary element between the primary and secondary windings. This coupling winding serves as a mediator that provides a controlled path for common mode currents while maintaining the galvanic isolation function of the transformer. The coupling winding is electrically coupled to ground, allowing it to intercept and divert capacitance currents away from the main isolation path.
Solution Approach 2:
The harmful interwinding capacitance current is extracted and diverted from the main transformer path by introducing the coupling winding. The coupling winding specifically targets and removes the common mode currents that would otherwise flow through the primary and secondary windings, separating the harmful current path from the useful signal path.
2Object-generated harmful factors
If shield terminal is added to direct current to ground, then common mode currents are reduced, but device complexity increases
Solution Approach 1:
The coupling winding serves multiple functions simultaneously: it maintains the galvanic isolation between primary and secondary, provides a path for common mode currents to ground, and does not interfere with the normal signal transmission. This multi-functionality reduces the need for additional separate components to address each issue individually.
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 effectively reduces primary common mode currents flowing through the transformer, protecting sensitive control circuitry by providing a path for common mode currents to ground, thereby maintaining galvanic isolation and preventing damage.
Implementation Method 1
a transformer includes a coupling winding and a primary winding that encircles a first portion of the coupling winding. Additionally, the transformer includes a secondary winding that encircles a second portion of the coupling winding. A shield terminal is electrically coupled to the coupling winding so that the shield terminal may direct a current in the coupling winding to ground.
Data Source
AI summary
Systems and methods are disclosed for reducing an interwinding capacitance current in a transformer. In certain embodiments, the transformer includes a coupling winding and a primary winding that encircles a portion of the coupling winding. Additionally, the transformer includes a secondary winding that encircles a portion of the coupling winding. The transformer includes a shield terminal which is electrically coupled to the coupling winding. The shield terminal directs currents, such as interwinding capacitance currents, in the coupling winding to ground.