Isolation Transformer Double-Shielded Winding Configuration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Isolated DC-to-DC switching power supplies experience high electrical noise due to high leakage inductance in existing isolation transformers, which causes displacement current across the isolation barrier.
Innovation Solution
The use of isolation transformers with a double-shielded or triaxial winding configuration, where the primary and secondary windings are completely isolated from each other, with electrostatic coupling only occurring between the winding-shields, reducing leakage inductance and capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrostatic winding-shielding is used between primary and secondary windings, then isolation between windings is improved, but leakage inductance increases causing high electrical noise
Solution Approach 1:
The transformer winding structure is segmented into distinct sections with separate winding-shields for primary and secondary windings. The primary winding-shield and secondary winding-shield are electrically isolated and positioned at different potentials, creating discrete isolation zones that prevent direct coupling between windings while maintaining magnetic coupling through the core.
Solution Approach 2:
Winding-shields are introduced as intermediary elements between the primary and secondary windings. These shields act as intermediate conductive layers that intercept and contain electric field lines, preventing direct electrostatic coupling between windings while allowing magnetic flux to pass through the core unchanged.
2Object-generated harmful factors
If bifilar winding technique is used, then leakage inductance is reduced, but electrostatic coupling between windings becomes uncontrolled causing displacement current
Solution Approach 1:
The continuous electrostatic field path in bifilar windings is segmented by introducing winding-shields between primary and secondary turns. This segmentation creates discrete capacitive coupling zones that are controlled and defined by the shield positions, preventing uncontrolled displacement current while preserving the low leakage inductance benefit of close winding.
Solution Approach 2:
Winding-shields serve as intermediary conductive barriers inserted between primary and secondary windings. These shields control the electrostatic coupling by providing defined capacitance paths through their geometry and positioning, eliminating uncontrolled displacement current while allowing the windings to remain close for low leakage inductance.
3Reliability
If primary and secondary windings are separated, then electrostatic coupling is reduced, but leakage inductance increases significantly
Solution Approach 1:
The isolation mechanism is moved from the spatial dimension (separating windings physically) to the electromagnetic dimension (using winding-shields to manage field coupling). Windings remain close in space for low leakage inductance, while winding-shields provide isolation by controlling electric field distribution in the electromagnetic domain.
Solution Approach 2:
Winding-shields are introduced as intermediary elements that provide electrostatic isolation without requiring physical separation of windings. These shields intercept and contain electric fields between windings, achieving isolation while allowing windings to remain in close proximity for low leakage inductance performance.
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 configuration significantly reduces noise across the isolation barrier, ensuring that voltage swings couple only to their respective shields, eliminating direct coupling between primary and secondary windings and minimizing displacement current.
Implementation Method 1
an electrostatic coupling between the primary and secondary windings occurs only between the primary winding-winding-shield and secondary winding-winding-shields
Implementation Method 2
an isolation transformer for an isolated switching DC-to-DC power supply, where an electrostatic coupling between the primary and secondary windings occurs only between the primary winding-winding-shield and secondary winding-winding-shields
Data Source
AI summary
An isolated DC-to-DC switching power supply includes an isolation transformer having a magnetic core, a first winding around the magnetic core, a first winding-shield around the magnetic core, a second winding-shield within the first winding-shield, and a second winding within the second winding-shield. There is no direct coupling between the first winding and the second winding since the second winding is enclosed within the second winding-shield and the second winding-shield is enclosed within the first winding-shield.