Isolated DC-DC Converter Circuit With Ring-Core Low-Ripple Output
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Solution Overview
Problem
Existing isolated DC-DC converters require gapped core transformers to prevent transformer saturation, leading to complex constructions and increased costs, and suffer from high ripple voltage and noise in the output.
Innovation Solution
An isolated DC-DC converter design that uses a ring-shaped core and transfers energy to the secondary side during both the on and off periods of the primary side switches, eliminating the need for a gapped core and reducing ripple voltage and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gapped core transformer is used to prevent saturation, then transformer saturation is avoided, but device complexity and manufacturing cost increase
Solution Approach 1:
Instead of using a conventional gapped core structure to prevent saturation, the patent inverts the approach by using a continuous closed-loop core without gaps and preventing saturation through operational control methods, specifically by ensuring the transformer operates only in the forward energy transfer mode during the switching cycle
Solution Approach 2:
The patent changes the operational parameters of the transformer by controlling the duty cycle of the switching circuit to ensure it remains below 50%, which prevents the magnetic flux from exceeding the saturation point during the off-state, thereby eliminating the need for a gapped core
2Reliability
If a larger core and more windings are used to avoid saturation, then transformer saturation is prevented, but device volume increases
Solution Approach 1:
The patent changes the operational duty cycle parameter to remain below 50%, which allows the use of a smaller core volume while preventing saturation through controlled operation rather than oversized design
Solution Approach 2:
Instead of designing for saturation prevention through physical oversizing, the patent inverts the approach by using precise operational control to achieve the same reliability with reduced component size
3Device complexity
If energy is provided only during Q1 off and Q2 on period, then transformer operation is simplified, but output ripple voltage and noise increase
Solution Approach 1:
The patent applies continuous energy transfer to the secondary side throughout the entire switching cycle by utilizing both the primary switch and secondary diode conduction periods, which smooths the output voltage and reduces ripple while maintaining simplified switching operation
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 prevents transformer saturation, simplifies the structure, reduces costs by eliminating the need for dedicated ICs, and minimizes output ripple and noise.
Implementation Method 1
The primary side and secondary side are coupled via the transformer formed from the inductor 108 in the primary side 102 and the inductor 110 in the secondary side 104
Data Source
AI summary
An isolated DC-DC converter includes a non-isolated DC-DC converter as a primary side. The non-isolated DC-DC converter includes a first inductor, a switch controller, and first and second switches. The non-isolated DC-DC converter is configured to receive an input voltage. The non-isolated DC-DC converter also includes a secondary side including a second inductor, a full wave rectifying circuit, and a filter circuit. The second inductor in the secondary side is coupled with the first inductor in the primary side to define a transformer. The secondary side is electrically isolated from the primary side by the transformer and is configured to output a DC voltage based on a voltage induced in the second inductor via the transformer.