Resonant DC-DC Converter Soft Switching
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Solution Overview
Problem
Conventional non-isolated step-down DC-DC converters with high output current suffer from high switching loss and low switching frequency due to hard switching, limiting the improvement of power conversion density.
Innovation Solution
A power conversion system that generates resonance among resonant capacitors and inductors by controlling switches, allowing switches to be turned off at zero current and on at zero voltage, and utilizes multiple power conversion circuits connected in parallel and interleaved to enhance load capacity and reduce current ripples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If hard switching is used in conventional DC-DC converters, then the circuit structure is simple, but the switching loss is high and switching frequency is low
Solution Approach 1:
The patent applies resonance (analogous to mechanical vibration) by introducing resonant capacitors and inductors to create oscillating current and voltage waveforms. This resonance enables the switches to operate at zero current or zero voltage moments, dramatically reducing switching losses while maintaining circuit feasibility through the added resonant elements.
Solution Approach 2:
The patent changes the switching strategy from fixed-duty-cycle hard switching to resonance-based soft switching. By utilizing the natural resonant frequency of the LC circuit, the switching timing is dynamically adjusted to occur at optimal moments (zero current for turn-off, zero voltage for turn-on), reducing energy loss during transitions.
2Power
If multiple power conversion circuits are connected in parallel and interleaved, then the load capacity is enlarged and current ripples are reduced, but the control complexity increases
Solution Approach 1:
The patent divides the power conversion system into multiple parallel modules, each handling a portion of the total load. This segmentation allows independent control of each module while achieving combined high power output. The interleaved operation of segmented modules further reduces current ripples through phase distribution.
Solution Approach 2:
The patent employs periodic interleaved operation where multiple parallel circuits are activated in alternating phases. This periodic action distributes the current demand over time, reducing peak currents and ripples while maintaining high average power capacity. The control complexity is managed through systematic phase shifting of the periodic operations.
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 switching loss and improves energy conversion efficiency, enabling a more compact and efficient power conversion system with increased power density.
Implementation Method 1
A resonance is generated among the resonant capacitors and inductors through controlling switches on and off. Accordingly, the switches can be turned off at zero current and can be turned on at zero voltage.
Implementation Method 2
The two windings are magnetically coupled to each other to form a transformer.
Data Source
AI summary
A power conversion system is provided. The power conversion system includes N power conversion circuits. Each power conversion circuit includes an input, an output, two switching power conversion units and at least one resonant capacitor. The input and output are configured to receive an input voltage and output an output voltage respectively. Each switching power conversion unit includes a plurality of switches and a winding. The plurality of switches operates periodically according to a switching period. A dotted terminal of one winding is electrically coupled to an undotted terminal of the other winding. The two windings are magnetically coupled to each other to form a transformer. In one switching period, the resonant capacitor stores an energy or outputs the stored energy as the corresponding switch is turned on or off. A resonance is generated between the resonant capacitor and inductor with a resonant frequency and a resonant period.