MMC Sub-Module Design for Shared Redundancy
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Solution Overview
Problem
Conventional modular multilevel converter (MMC) systems require separate redundant sub-modules for upper and lower converter arms, leading to increased complexity and cost.
Innovation Solution
A sub-module design that is commonly applicable to both upper and lower converter arms, featuring a first and second power semiconductor switch connected in series with a capacitor in parallel, and a third power semiconductor switch connected to an AC grid system, allowing for shared redundancy between the arms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate redundant sub-modules are provided for upper and lower converter arms, then reliability is improved through redundancy, but device complexity and cost increase
Solution Approach 1:
The patent applies universality by designing a redundant sub-module that can be commonly applied to both upper converter arm and lower converter arm. The sub-module includes power semiconductor switches connected in series with a capacitor in parallel, and can function in both arms through appropriate connection configurations, eliminating the need for separate redundant sub-modules for each arm.
Solution Approach 2:
The patent merges the redundant sub-module design into a unified structure that serves both upper and lower converter arms. By combining the redundancy function into a single shared sub-module rather than providing separate redundant modules for each arm, the overall device complexity is reduced while maintaining reliability.
2Reliability
If separate redundant sub-modules are provided for upper and lower converter arms, then reliability is improved through redundancy, but cost increases
Solution Approach 1:
The patent applies universality by designing a redundant sub-module that can be commonly applied to both upper converter arm and lower converter arm. The sub-module includes power semiconductor switches connected in series with a capacitor in parallel, and can function in both arms through appropriate connection configurations, eliminating the need for separate redundant sub-modules for each arm.
3Device complexity
If a common sub-module design is used for upper and lower converter arms, then device complexity is reduced, but adaptability must be maintained across different arm configurations
Solution Approach 1:
The patent applies universality by designing a redundant sub-module that can be commonly applied to both upper converter arm and lower converter arm. The sub-module includes power semiconductor switches connected in series with a capacitor in parallel, and can function in both arms through appropriate connection configurations, eliminating the need for separate redundant sub-modules for each arm.
Data Source
AI summary
An MMC converter linked to a HVDC system and a sub-module are proposed. The sub-module includes: first and second power semiconductor switches serially connected in the same direction, each including a semiconductor switch and a diode connected in anti-parallel to the semiconductor switch; a capacitor parallelly connected to the first and second power semiconductor switches serially connected; a first terminal connected to a first node between the first and second power semiconductor switches; a second terminal connected to a second node between the second power semiconductor switch and the capacitor; a third power semiconductor switch of which a side is connected to the second node, the third power semiconductor switch including a semiconductor switch and a diode connected in anti-parallel to the semiconductor switch; and a third terminal connected to a terminal of an AC grid system and connected to the other side of the third power semiconductor switch.