Complementarily Driven DC-DC Converter for High Current
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Solution Overview
Problem
Conventional DC-DC converters using capacitors and diodes face limitations in increasing charging/discharging current to support large load currents, resulting in high losses at diodes and switching elements, which reduces power conversion efficiency and generates excessive heat.
Innovation Solution
The proposed DC-DC converter employs n number of series circuits with inductors and switching elements in parallel, along with a second series circuit of rectifier elements, where a capacitor connects nodes between the inductor and switching elements, and a switching control circuit drives the switching elements to complementarily charge/discharge, eliminating the need for rectifier diodes and reducing losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a charge pump boosting circuit uses only capacitors and diodes for voltage boosting, then the circuit structure is simple, but the charging/discharging current is limited and large load currents cannot be supported
Solution Approach 1:
The patent divides the single boosting circuit into multiple parallel boosting circuits (first and second boosting circuits). Each circuit includes its own inductor, switching element, and rectifier element. This segmentation allows the total output current to be the sum of currents from multiple circuits, thereby supporting large load currents while maintaining relatively simple individual circuit structures.
2Reliability
If voltage doubling rectification is performed using two diodes after direct-current voltage generation, then the rectification function is achieved, but large losses occur at the diodes
Solution Approach 1:
The patent changes the type of rectifier element from traditional diodes to synchronous rectification using switching elements (MOSFETs). The switching elements are controlled to operate in synchronous rectification mode, where the on-resistance is much lower than diode forward voltage drop, significantly reducing rectification losses. This parameter change transforms the rectification mechanism from passive diode conduction to active switching element control.
3Power
If a large pulsed current flows from the capacitor into the switching element, then voltage boosting is achieved, but large losses and heat generation occur at the switching element
Solution Approach 1:
The patent segments the current path by introducing separate inductors for each boosting circuit. The inductors limit and smooth the current flow, preventing large pulsed currents from directly flowing into the switching elements. This segmentation of the current path reduces switching losses and heat generation while maintaining voltage boosting capability.
4Loss of energy
If the capacitance of the capacitor is reduced to decrease pulsed current, then switching element losses are reduced, but the ability to output large current is compromised
Solution Approach 1:
The patent uses multiple parallel boosting circuits, each with its own capacitor and inductor. This allows the total output current capability to be the sum of individual circuit capabilities. Even if individual capacitors are smaller, the parallel configuration maintains high current output capability while reducing pulsed current stress on switching elements.
Solution Approach 2:
The patent transitions from a single-dimensional solution (one capacitor value) to a multi-dimensional solution (multiple capacitors in parallel configurations). By distributing the capacitance across multiple parallel circuits, the system achieves both reduced pulsed current (smaller individual capacitors) and high output current capability (cumulative effect of parallel capacitors).
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 the total charging/discharging current, supports large load supply currents, and reduces losses at diodes and switching elements, leading to a low-heat-generating and high-power-conversion-efficiency DC-DC converter.
Implementation Method 1
n number of first series circuits each including an inductor and a switching element
Implementation Method 2
a node between the rectifier elements in the second series circuit and a node between the inductor and the switching element in remaining (n−1) number of the first series circuits are connected via a capacitor
Data Source
AI summary
A DC-DC converter includes n number of first series circuits each including an inductor and a switching element and a second series circuit in which n number of rectifier elements are connected in series with a same rectification direction. When n=2, one end of the second series circuit is connected to a node between an inductor and a switching element in the first series circuit and the other end of the second series circuit is connected to one end of a smoothing capacitor and one end of a load. A node between an inductor and a switching element is connected to a node between the rectifier elements via a capacitor. The odd-numbered switching element and the even-numbered switching element in the order of connection to the second series circuit are complementarily driven.