Voltage Source Converter Cell With Dynamic Bypass Switching
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Solution Overview
Problem
Conventional voltage source converters (VSCs) face challenges in efficiently managing current flow between cell terminals, particularly in high-voltage direct current (HVDC) systems, where the number of semiconductor switches required for active and bypass states can lead to increased cost, size, and power losses due to redundant components.
Innovation Solution
The use of dual-switch semiconductor packages in a modular configuration, where a first set of switches is active during active states and disconnected during bypass states, and a second set with more switches in parallel handles higher currents during bypass states, reducing the need for redundant components and optimizing current handling capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional VSC configurations are used with sufficient semiconductor switches for both active and bypass states, then reliable current handling is achieved, but device complexity and cost increase due to redundant components
Solution Approach 1:
The patent applies dynamics by making the switching apparatus reconfigurable between active and bypass states. The semiconductor switches are dynamically controlled to be connected in parallel during bypass states to handle higher currents, and reconfigured during active states. This dynamic reconfiguration allows the same hardware to adapt its characteristics based on operational requirements, eliminating the need for permanently oversized switches and reducing overall device complexity while maintaining reliability.
2Reliability
If semiconductor switches are sized to handle maximum current in bypass states, then adequate current capacity is ensured, but power losses increase due to higher current ratings
Solution Approach 1:
The switching apparatus dynamically adjusts the effective current capacity of the semiconductor switches by connecting them in parallel during bypass states. This allows lower-rated switches to collectively handle high bypass currents without each individual switch being oversized, thereby reducing conduction losses while maintaining adequate current capacity when needed.
Solution Approach 2:
The patent merges multiple semiconductor switches in parallel during bypass states to share the high current load. By combining the current handling capability of multiple smaller switches rather than using a single large switch, the system reduces overall power losses while achieving the required current capacity for bypass operations.
3Reliability
If multiple semiconductor switches are used in parallel for bypass states, then current handling capability is improved, but device size and cost increase
Solution Approach 1:
The semiconductor switches are designed with multi-functionality, serving dual purposes: handling moderate currents during active states and collectively handling high currents during bypass states when connected in parallel. This universal design allows the same switches to fulfill different functional requirements without requiring separate dedicated components, thereby reducing overall device size and eliminating redundancy.
Solution Approach 2:
The system dynamically reconfigures the connection topology of semiconductor switches between series/parallel arrangements based on operational state. During bypass states, switches are connected in parallel to increase current handling capability, and during active states, they are reconfigured. This dynamic adaptability allows lower-rated switches to be used, reducing device size and cost while maintaining adequate current handling capability when required.
Data Source
AI summary
This application relates to a cell (1200) or sub-module for a voltage source converter (1201). The cell includes an energy storage apparatus (101; 101a, 101b) and a plurality of dual-switch semiconductor packages (201), each having first and second semiconductor switches (202, 203) connected in series. The cell is operable in an active state in which an energy storage apparatus (101; 101a, 101b) is electrically connected in series between cell terminals (102a, 102b) and a bypass state in the cell terminals (102a, 102b) are electrically connected via a path that bypasses the first energy storage apparatus. The plurality of dual-switch semiconductor switch packages are configured to provide a first set of semiconductor switches (301; 401) connected between nodes of the cell that are electrically connected in the first active state and electrically disconnected in the first bypass state; and a second set of semiconductor switches (302a, 302b; 402a, 402b) is connected between nodes of the cell that are electrically disconnected in the first active state and electrically connected in the bypass state. The second set of switches comprises a greater number of switches in parallel than the first set of switches.