Power Conversion Device With Adjustable Branches For Wide Voltage Range
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Solution Overview
Problem
Conventional power conversion devices face challenges in achieving high efficiency and compact size while providing a wide range of output voltage, particularly in applications like electric vehicle charging stations that require output voltages from 200-1000V with power ranging from 50kW to 300kW.
Innovation Solution
A power conversion device with multiple conversion branches, each comprising first-stage isolated converters connected in series or parallel, allowing for controlled operation or non-operation to generate a continuous and adjustable wide range of output voltage, utilizing bypass elements to manage current flow when branches are non-operational.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PWM converter is used for wide range output voltage regulation, then output voltage range is improved, but switching frequency is reduced resulting in larger size and lower efficiency
Solution Approach 1:
The power conversion device is divided into multiple conversion branches (first conversion branch and second conversion branch), each capable of operating independently or in combination. This segmentation allows the system to achieve wide output voltage range by selectively activating different branches while maintaining high efficiency through series resonant operation in each branch.
Solution Approach 2:
The controller dynamically adjusts the operation state of each conversion branch based on the required output voltage. By controlling the switching between different branch configurations (one branch active, both branches active, or different combinations), the system achieves continuous wide range voltage regulation while maintaining optimal operating conditions for high efficiency.
2Loss of energy
If PFM converter is used for high frequency operation, then converter size is reduced and efficiency is improved, but output voltage regulation range becomes narrow
Solution Approach 1:
Multiple series resonant conversion branches are merged in parallel configuration, where each branch operates as a high-frequency efficient PFM converter. By combining the output of these branches through series connection of their secondary windings, the system achieves both high efficiency (from individual branch operation) and wide voltage range (from combined output).
Solution Approach 2:
Each conversion branch is designed with universal functionality to operate independently or in combination with other branches. The series resonant converter topology provides multi-functionality, enabling the same basic circuit structure to serve different voltage regulation needs by simply activating different branch combinations.
3Adaptability or versatility
If multiple conversion branches are added to achieve wide voltage range, then output voltage range is improved, but device complexity increases
Solution Approach 1:
The conversion branches use homogeneous series resonant converter topologies with identical or similar circuit structures. This homogeneity simplifies the overall system design, as each branch can be designed and controlled using the same principles, reducing the complexity increase that would result from using different converter topologies for each branch.
4Adaptability or versatility
If series connection of converter outputs is used to increase voltage, then output voltage range is improved, but control complexity increases
Solution Approach 1:
The controller implements feedback control to monitor the combined output voltage from multiple conversion branches and dynamically adjusts the switching states and duty cycles of individual branches. This feedback mechanism simplifies the control complexity by providing automatic regulation, eliminating the need for complex manual coordination of multiple branches.
Data Source
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AI summary
The disclosure discloses a power conversion device and a power conversion system. The power conversion device comprises a plurality of conversion branches, each comprising an input terminal and an output terminal. The input terminals of the plurality of conversion branches are connected in parallel, and the output terminals of the plurality of conversion branches are connected in series. An output voltage of the power conversion device is a sum of voltages at the output terminals of the plurality of conversion branches. The plurality of conversion branches are controlled to enter an operating state or a non-operating state, so as to make the output voltage of the power conversion device adjustable and continuous.