Directly Coupled Inductor for DC-DC Converter Miniaturization
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Solution Overview
Problem
Current DC-DC converters face limitations in reducing physical size due to the need for multiple output inductors and filter capacitors, with indirectly coupled inductors offering only partial size reduction while being constrained by efficiency and current ripple issues.
Innovation Solution
The design incorporates a directly coupled inductor with a magnetic core and a conductive sheet in a comb structure, where each power-switching phase has a high-side and low-side switch activated alternately, forming a toroidal inductor with a single loop coil, and no switches are activated simultaneously, reducing inductance and current ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If indirectly coupled inductors are used to reduce physical footprint, then the size of DC-DC converter is reduced, but efficiency and current ripple performance deteriorate
Solution Approach 1:
The patent combines multiple inductors into a single directly coupled inductor structure where multiple windings share a common magnetic core. This merging approach reduces the overall physical footprint while maintaining the electrical performance of individual inductors, resolving the contradiction between size reduction and performance maintenance
Solution Approach 2:
The patent inverts the traditional indirectly coupled inductor approach by using directly coupled inductors with a shared magnetic core. Instead of isolating inductors to maintain performance, the invention couples them directly with precise control, achieving both compact size and maintained efficiency through alternative coupling methodology
2Power
If multiple switches are activated simultaneously in indirectly coupled inductors, then power switching is achieved, but current ripple increases and efficiency decreases
Solution Approach 1:
The patent implements periodic switching of power switches in a controlled sequence rather than simultaneous activation. By using complementary switching patterns where switches are activated in alternating phases, the system maintains continuous power transfer while reducing current ripple and improving efficiency through periodic rather than simultaneous switch operation
Solution Approach 2:
The patent ensures continuous useful action by overlapping the off-times of different switches, guaranteeing that at least one switch is conducting at any given moment. This continuous conduction mode maintains steady power flow and reduces current ripple, preventing energy losses associated with discontinuous operation
3Volume of moving object
If the number of output inductors and filter capacitors is reduced, then physical size is decreased, but device complexity in control increases
Solution Approach 1:
The patent makes the directly coupled inductor structure multi-functional by using it for both energy storage and current ripple filtering simultaneously. The shared magnetic core performs multiple functions that would traditionally require separate components, reducing overall component count while the control complexity is managed through unified rather than distributed control logic
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 increases system efficiency, reduces current ripple, and allows for further miniaturization of DC-DC converters by inversely proportional reduction in inductance with the number of phases, enhancing overall performance.
Implementation Method 1
The tab extending through the magnetic core forms, for each power-switching phase, a toroidal inductor with a single loop coil
Data Source
AI summary
A DC-DC converter includes power-switching phases which each include a high-side and low-side switch. The high-side switch is coupled to the low-side switch at a connection node. The converter also includes a coupled inductor formed of a magnetic core and a conductive sheet. The sheet is formed of a comb structure having a tab and teeth extending from the tab. The conductive sheet is inserted into a slot defined by the magnetic core and extends through the magnetic core with a portion of the tab protruding from the back and a portion of each tooth protruding from the front of the core. Each tooth is coupled to a connection node of a phase and the tab extending through the core forms a toroidal inductor with a single loop coil for each phase, and for all the phases, a directly coupled inductor.