Coupled Output Inductor Topology for Low-Ripple DC-DC Conversion
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Solution Overview
Problem
Conventional DC-DC conversion devices in satellite bus power systems suffer from high output current ripple, leading to premature degradation of output capacitors and reduced satellite lifespan, and the addition of more active elements increases complexity, volume, weight, and cost.
Innovation Solution
A DC-DC conversion device with a coupling inductor configuration, including a first and second transformer with magnetically coupled inductors, and switches controlled by a control unit, where the output inductor is magnetically coupled to the third and fourth inductors, reducing the number of active elements and complexity, and minimizing ripple in the output current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If additional active elements (third switch Q3 and fourth switch Q4) are added to reduce output current ripple, then the ripple of output current is reduced, but the control complexity and device volume increase
Solution Approach 1:
The invention extracts the ripple reduction function from the active switch domain and transfers it to the passive magnetic component domain. By designing the coupling inductor with specific winding configurations (first winding and second winding with opposite directions) and utilizing the natural electromagnetic coupling between inductors, the ripple reduction effect is achieved without requiring additional active switching elements, thereby avoiding increased control complexity
Solution Approach 2:
The coupling inductor acts as an intermediary element that mediates between the input and output circuits. The magnetic coupling between the first and second windings of the coupling inductor creates an indirect current path that naturally filters the output current ripple, replacing the need for direct active element control while achieving the same harmful factor reduction
2Object-affected harmful factors
If additional active elements (third switch Q3 and fourth switch Q4) are added to reduce output current ripple, then the ripple of output current is reduced, but the volume and weight of the device increase
Solution Approach 1:
The invention merges the coupling inductor function with the output inductor function into a single integrated magnetic component. The coupling inductor's second winding serves dual purposes: it provides the coupling effect for ripple reduction while also functioning as the output inductor. This consolidation eliminates the need for separate third and fourth switches and their associated drive circuits, thereby reducing overall device weight
3Object-affected harmful factors
If additional active elements (third switch Q3 and fourth switch Q4) are added to reduce output current ripple, then the ripple of output current is reduced, but the number of drivers and device cost increase
Solution Approach 1:
The invention extracts the ripple reduction functionality from the active switching domain and implements it through passive magnetic coupling mechanisms. By utilizing the natural electromagnetic induction between windings of the coupling inductor, the system achieves current ripple filtering without requiring additional gate drivers or complex control circuits, thereby reducing both the number of drivers and associated costs
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
Significantly reduces output current ripple, decreases the number of active elements and drivers, resulting in reduced volume, weight, and cost, while extending the lifespan of output capacitors and the satellite.
Implementation Method 1
a first transformer connected between a ground and a first node between an input terminal to which an input voltage is applied and an output terminal to which an output voltage is applied, and including a first inductor and a second inductor that are magnetically coupled to each other
Implementation Method 2
a second transformer positioned between the input terminal and the output terminal and including a third inductor and a fourth inductor that are magnetically coupled to each other
Implementation Method 3
an output inductor connected to the fourth node and the output terminal, in which the output inductor may be magnetically coupled to the third inductor and the fourth inductor
Data Source
AI summary
According to the present invention, an output inductor, rather than being composed of a separate inductor element, is magnetically coupled to a third inductor and a fourth inductor constituting a second transformer. Thus, compared to the case in which the output inductor is composed of the separate inductor element independently of the third inductor and the fourth inductor, the cost as well as the volume of the DC-DC conversion device can be reduced.