Multilevel Converter Leg With Diode and Switch Strings
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Solution Overview
Problem
Current multilevel converters, particularly modular multilevel converters, require a large number of fully controllable semiconductor switches, which can increase complexity and cost, and existing designs often rely on non-controllable or uncontrollable semiconductor switches, limiting efficiency and scalability.
Innovation Solution
A power converter design featuring a leg with a first string of diodes and a second string of fully controllable semiconductor switches, where the second string includes energy storage devices and switching units, allowing for reduced switch ratings and improved efficiency through controlled voltage regulation across multiple levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If modular multilevel converters are designed with a large number of fully controllable semiconductor switches, then the power conversion capability and voltage level are improved, but the device complexity and cost increase significantly
Solution Approach 1:
The converter is divided into multiple legs, each leg containing multiple switching units that can be independently controlled. Each switching unit processes a portion of the total power, allowing the system to achieve high power capability through parallel modular structures rather than requiring a single complex high-power switch configuration
Solution Approach 2:
The switching units are designed with universal functionality to handle multiple operating modes and voltage levels. Each switching unit can operate independently or in combination with others, providing multi-functionality that reduces the need for specialized components for different power levels and application scenarios
2Power
If modular multilevel converters use a large number of fully controllable semiconductor switches, then the voltage level and power capability are improved, but the cost increases
Solution Approach 1:
The high voltage capability is achieved by segmenting the converter into multiple switching units connected in series within each leg. Each switching unit operates at a lower voltage level, allowing the use of more economical semiconductor switches while achieving high overall voltage through the series connection of multiple units
Solution Approach 2:
The converter employs identical or similar switching units repeated across multiple legs and levels. This copying approach allows for standardized manufacturing processes, bulk procurement of components, and simplified assembly, thereby reducing the overall cost despite the large number of switches required for high voltage operation
3Device complexity
If non-controllable or uncontrollable semiconductor switches are used in multilevel converters, then the device complexity is reduced, but the efficiency and scalability are limited
Solution Approach 1:
The converter employs fully controllable semiconductor switches that enable dynamic control of power flow, switching timing, and voltage regulation. This dynamic control capability allows the converter to adapt to varying load conditions, optimize efficiency, and scale flexibly to different power levels, overcoming the limitations of static non-controllable switch configurations
Data Source
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AI summary
A power converter (104) is presented. The power converter includes at least one leg (300), the at least one leg includes a first string (302), where the first string includes a plurality of diodes (330), a first connecting node (310), and a second connecting node (312), and where the first string is operatively coupled across a first bus (306) and a second bus (308). Furthermore, the at least one leg includes a second string (304) operatively coupled to the first string via the first connecting node and the second connecting node, where the second string includes a plurality of switching units (334).