DC-DC Boost Converter With Three-State Switching Cell
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Solution Overview
Problem
Existing DC-DC converters for high power and high voltage applications face challenges in achieving high efficiency, high power density, and low cost due to high voltage stress on switches, high power losses, and the expense of silicon carbide semiconductors, while traditional solutions often compromise between efficiency and density, leading to increased volume and cost.
Innovation Solution
A DC-DC boost converter utilizing a three-state switching cell with interleaving characteristics, series connection of semiconductors to reduce voltage stress, and parallel connection to reduce current stress, along with a simplified passive snubber and voltage balancing networks, allowing for high frequency operation with standard silicon semiconductors to achieve high efficiency and power density at lower costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If high voltage semiconductors are used to handle high voltage applications, then the voltage handling capability is improved, but the cost increases and efficiency decreases
Solution Approach 1:
The patent divides the high voltage handling task into multiple segments by using multiple semiconductor switches in series. Each switch handles a portion of the total voltage (e.g., if total voltage is 1200V and 4 switches are used in series, each switch handles 300V), allowing the use of lower voltage-rated, more efficient semiconductors while maintaining the required voltage handling capability of the overall converter.
2Volume of stationary object
If switching frequency is increased to reduce reactive component size, then power density is improved, but switching losses increase reducing efficiency
Solution Approach 1:
The patent changes the operating parameters of the semiconductor switches by optimizing their voltage and current ratings to match the segmented architecture. By selecting switches with appropriate parameters (lower voltage rating but optimized for the specific operating conditions), the converter achieves low switching losses even at high switching frequencies, enabling both high efficiency and high power density.
3Power
If multiple converters are paralleled to handle high current applications, then current handling capability is improved, but current sharing problems and complexity increase
Solution Approach 1:
The patent merges multiple semiconductor switches into a single integrated converter topology rather than paralleling separate converters. The multiple switches operate within one unified control framework, eliminating current sharing problems between independent converters while maintaining high current handling capability. This integrated approach reduces overall system complexity despite using multiple switching devices.
4Loss of energy
If silicon carbide semiconductors are used to achieve high efficiency at high voltage, then efficiency is improved, but cost increases significantly
Solution Approach 1:
The patent uses conventional, cost-effective semiconductor materials (such as silicon-based switches) instead of expensive silicon carbide devices. By segmenting the voltage handling and optimizing the switching strategy, the system achieves high efficiency with cheaper, more readily available semiconductors, making the converter more economically viable for commercial applications.
Data Source
Figure 1(a)~1(b)
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AI summary
The present invention relates to a DC-DC boost converter for photovoltaic applications, where the DC-DC converter comprises an input terminal (14), and an output terminal (6) and a first autotransformer (37) comprising an intermediate terminal (15) and first and second end terminals (16, 17), a first diode (19), one terminal of which is coupled to said first end terminal (16), a second diode (20), one terminal of which is coupled to said second end terminal (17); where the second terminals of said diodes are connected to said output terminal (6); and where the output terminal (6) is coupled to said common terminal (8) of the converter through a first capacitor (10). In the converter according to the invention the first and second end terminals (16, 17) of the first autotransformer (37) are respectively connected to first and third terminals (55, 59) of a three-state switching cell (21), and second and fourth terminals (56, 60) of the three-state switching cell (21) are connected to the common terminal (8) of the converter. Preferably, the converter of the invention is provided with a snubber circuit (36, 18) between the input terminal and the output terminal of the converter in order to minimize the recovery current of boost diodes added to the three-state switching cell.