Two-Stage DC-DC Converter for Wide Voltage Range Efficiency
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Solution Overview
Problem
DC-DC converters face challenges in achieving high power density and wide input/output voltage range while maintaining high conversion efficiency, as single-stage topologies often suffer from low efficiency when dealing with wide voltage ranges.
Innovation Solution
A two-stage DC-DC converter configuration is employed, comprising a multi-level converter stage for voltage regulation and a fixed voltage ratio converter stage, where the multi-level stage can be either a buck or boost converter, and the fixed voltage ratio stage is typically an LLC resonant converter, to achieve high efficiency and power density across a wide voltage range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If single-stage converter topologies (LLC, phase-shifted full-bridge, DAB) are used, then high power density and high conversion efficiency can be achieved, but the efficiency drops significantly when input and/or output voltage range is wide
Solution Approach 1:
The converter is divided into two independent stages: a multi-level converter stage (buck or boost) for wide voltage range adaptation and a fixed voltage ratio converter stage (LLC, phase-shifted full-bridge, or DAB) for high efficiency power conversion. Each stage operates within its optimal voltage range, resolving the contradiction between wide voltage adaptability and high conversion efficiency.
2Adaptability or versatility
If two-stage DC-DC converters with different converter topologies for each stage are used, then wide voltage range adaptability is improved, but device complexity increases
Solution Approach 1:
The converter is divided into two independent stages: a multi-level converter stage (buck or boost) for wide voltage range adaptation and a fixed voltage ratio converter stage (LLC, phase-shifted full-bridge, or DAB) for high efficiency power conversion. Each stage operates within its optimal voltage range, resolving the contradiction between wide voltage adaptability and high conversion efficiency.
3Adaptability or versatility
If multi-level converter stages (buck or boost) are used to regulate bus voltage, then wide input voltage range is handled effectively, but the overall device complexity increases compared to single-stage topologies
Solution Approach 1:
The converter is divided into two independent stages: a multi-level converter stage (buck or boost) for wide voltage range adaptation and a fixed voltage ratio converter stage (LLC, phase-shifted full-bridge, or DAB) for high efficiency power conversion. Each stage operates within its optimal voltage range, resolving the contradiction between wide voltage adaptability and high conversion efficiency.
Data Source
AI summary
According to one aspect, an apparatus comprising a two stage DC-DC converter is provided. The converter consists of a multilevel DC-DC converter stage cascaded with a fixed voltage ratio DC-DC converter stage. The converter is controlled so that a first stage of the converter provides an optimized output (a regulated bus voltage) which serves as the input to the second stage. The multilevel DC-DC converter may be the first stage and the fixed voltage ratio, unregulated DC-DC converter may be the second stage converter. Alternatively, the fixed voltage ratio, unregulated DC-DC converter may be the first stage and the multilevel DC-DC converter may be the second stage.