Power Electronic Transformer With Series-Input LLC DC/DC Modules
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Solution Overview
Problem
Conventional power electronic transformers require a large number of power conversion modules due to limited rated voltages of switching semiconductor components, leading to complex designs, increased space, and higher costs.
Innovation Solution
The use of LLC resonant DC/DC units in power conversion modules, where input ends are connected in series and output ends in parallel, with multiple switching transistors in series to increase voltage handling capacity, reducing the overall number of modules needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional power electronic transformers use limited voltage-rated switching semiconductor components, then the transformer can be built with standard components, but a large number of power conversion modules are required
Solution Approach 1:
The patent divides the high-voltage power conversion task into multiple low-voltage LLC resonant DC/DC units connected in series. Each unit handles a portion of the total voltage, allowing the use of standard voltage-rated semiconductor components while reducing the total number of power conversion modules required. This segmentation approach transforms a single complex high-voltage module into multiple simpler low-voltage units.
Solution Approach 2:
The patent implements a hierarchical structure where multiple LLC resonant DC/DC units are nested within power conversion modules, which are in turn nested within the overall power electronic transformer system. This nested architecture allows for modular assembly and reduces the total number of external modules needed by integrating multiple functions within each power conversion module.
2Power
If a large number of power conversion modules are used to handle high voltage, then the voltage handling requirement is met, but the occupied space and costs increase
Solution Approach 1:
The patent merges multiple LLC resonant DC/DC units within a single power conversion module, combining their functions to handle high voltage collectively. This consolidation reduces the total number of separate modules required, thereby decreasing the occupied space while maintaining the necessary voltage handling capacity through the series connection of switching transistors.
Solution Approach 2:
The patent transitions from a single-dimensional approach (one high-voltage module) to a multi-dimensional approach by connecting multiple low-voltage units in series. This dimensional change in voltage handling allows the system to achieve high voltage capacity without proportionally increasing the physical footprint, as the series connection efficiently stacks voltage handling capability.
3Power
If multiple power conversion modules are used, then the voltage handling is sufficient, but the number of matching circuit boards increases
Solution Approach 1:
The patent designs power conversion modules with universal functionality that can handle multiple voltage levels through the series connection of LLC resonant DC/DC units. Each module is designed to be multi-functional, capable of operating at different voltage ratings depending on the number and configuration of units within it, thereby reducing the need for multiple specialized circuit boards for different voltage levels.
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 decreases the number of power conversion modules, simplifying the design, reducing space and costs, while improving voltage handling and reducing harmonic waves and ripple currents, enabling soft switching and automatic voltage balancing.
Implementation Method 1
Each DC/DC circuit includes n LLC resonant DC/DC units
Data Source
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AI summary
This application discloses a power electronic transformer and a power supply system. The power electronic transformer is a single-phase power electronic transformer or a three-phase power electronic transformer. Each phase includes a plurality of power conversion modules. Each power conversion module includes a rectifier AC/DC circuit, a direct current bus capacitor, and a direct current-direct current DC/DC circuit; in each power conversion module, an output end of the AC/DC circuit is connected to an input end of the DC/DC circuit; the direct current bus capacitor is connected in parallel to the output end of the AC/DC circuit; and input ends of all the AC/DC circuits are connected in series, and output ends of all the DC/DC circuits are connected in parallel. Each DC/DC circuit includes n LLC resonant DC/DC units, where input ends of the n LLC resonant DC/DC units are connected in series and then connected to the output end of the corresponding AC/DC circuit, output ends of the n LLC resonant DC/DC units are connected in parallel and serve as an output end of the DC/DC circuit, and n is an integer greater than or equal to 2. The power electronic transformer includes a relatively small quantity of power conversion modules, thereby reducing occupied space and costs.