Modular Voltage Source Converter With Bipolar Cells
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Solution Overview
Problem
Existing voltage source converters based on cascaded cells lack enhanced functionality and simplified control schemes while maintaining low additional costs.
Innovation Solution
A modular voltage source converter structure is introduced, featuring cells with unipolar and bipolar voltage contribution capabilities, allowing for separate selection of cells based on basic and additional functionalities, and a control unit to manage these cells for enhanced AC voltage generation and reactive power capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a modular voltage source converter structure with separate cell groups is implemented, then enhanced functionality and simplified control are achieved, but device complexity increases due to additional cell types and configurations
Solution Approach 1:
The converter is divided into two distinct cell groups: a first group of cells providing basic voltage contribution for AC-DC conversion, and a second group of cells providing additional functionality such as circulating current reduction and third harmonic injection. This segmentation allows each group to be optimized for its specific function while maintaining overall system versatility.
Solution Approach 2:
The second group of cells is designed to provide multiple functions including reducing circulating currents between phase legs, providing third harmonic zero sequences for enhanced AC voltage generation, and contributing to reactive power capabilities. This multi-functionality approach enhances converter adaptability without requiring separate dedicated components for each function.
2Adaptability or versatility
If additional cells are added for enhanced functionality, then converter capabilities are improved, but cost increases due to additional components
Solution Approach 1:
The second group of cells is designed to perform multiple functions simultaneously: reducing circulating currents between phase legs, providing third harmonic zero sequences for enhanced AC voltage generation, and contributing to reactive power capabilities. This multi-functionality maximizes the utility of each additional cell, improving converter capabilities while minimizing the number of components required.
Data Source
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AI summary
The invention concerns a voltage source converter (26) comprising a group of phase legs, at least three connection terminals (AC1, AC2, AC3, DC+, DC-) for connecting the phase legs to power transmission elements, a first group of cells (C1p1, C2p1, C1n1, C2n1, C1p2, C2p2, C1n2, C2n2, C1p3, C2p3, C1n3, C2n3) ineach phase leg and a second group of cells (C3p1, C3n1,C3p2, C3n2 C3p3, C3n3). The cells (C1p1, C2p1, C1n1, C2n1, C1p2, C2p2, C1n2, C2n2, C1p3, C2p3, C1n3, C2n3) in the first group are only capable of providing unipolarvoltage contributions to the converterand connected for only being capable of such unipolar voltage contributions, while the cells (C3p1, C3n1,C3p2, C3n2 C3p3, C3n3) in the second group are connected to the corresponding cells of the first group and arranged to have bipolar voltage contribution capability.