Telescopic Arm Multilevel Converter for High-Voltage Applications
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Solution Overview
Problem
High-voltage multilevel converter systems face challenges such as increased complexity and difficulty in voltage sharing as the level number rises, and existing technologies are unsuitable for high-voltage applications due to limitations in modularization and electromagnetic compatibility.
Innovation Solution
A free telescopic arm-based multilevel converter topology is proposed, inspired by the crawling bionics of silkworms, which allows for modularization and automatic voltage sharing among modules, reducing the complexity and enhancing electromagnetic compatibility by regulating neutral point potential through telescopic arm action.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If switch series connection technology is used to achieve high-voltage conversion, then the withstanding voltage requirement is met, but electromagnetic compatibility deteriorates and reliability decreases due to extremely high change rate in switching voltage
Solution Approach 1:
The patent divides the high-voltage conversion function into multiple independent converter units connected in series, where each unit operates at lower voltage levels. This segmentation approach allows the system to achieve high-voltage withstanding capability while each individual unit maintains reliable and controlled switching operations, avoiding the electromagnetic compatibility issues associated with single high-voltage switching.
2Stress or pressure
If the number of series connections is increased to meet higher voltage requirements, then withstanding voltage is improved, but voltage sharing control becomes more difficult and requires larger withstanding voltage margin
Solution Approach 1:
The patent incorporates voltage sharing control mechanisms that continuously monitor the voltage across each series-connected converter unit and provide feedback signals. This feedback enables dynamic adjustment of switching patterns to maintain balanced voltage distribution across all units, simplifying the control of multi-series connections and reducing the required withstanding voltage margin for each individual unit.
3Reliability
If multilevel circuit is used to improve electromagnetic compatibility and reliability, then the converter can meet high-voltage operating requirements, but the complexity of the circuit increases with the level number
Solution Approach 1:
The patent employs a modular multilevel converter architecture where the circuit is divided into multiple identical converter units, each contributing a specific voltage level. This segmentation allows the system to achieve high voltage levels and improved electromagnetic compatibility through controlled switching at each level, while the modular structure prevents exponential complexity growth by maintaining uniformity across all units.
Solution Approach 2:
The patent implements dynamic switching control in the multilevel converter, where the switching patterns of individual units are dynamically adjusted based on operating conditions. This dynamic approach enables the converter to optimize its performance and maintain simplicity by adaptively selecting which units to activate, rather than requiring all units to operate simultaneously at fixed patterns.
4Stress or pressure
If conventional high-voltage power semiconductor devices with higher withstanding voltage are used, then the voltage requirement is met, but the cost increases significantly
Solution Approach 1:
The patent segments the high-voltage requirement across multiple conventional power semiconductor devices connected in series, where each device operates within its optimal withstanding voltage range. This approach enables the system to achieve high-voltage capability using cost-effective conventional devices rather than expensive high-voltage-rated devices, while the series connection topology maintains overall system reliability.
Data Source
AI summary
A converter bridge arm suitable for high-voltage applications and an application system thereof. The converter bridge arm comprises an energy storage capacitor (C) and a plurality of reverse-conducting switches, and is formed by serial connection of an upper telescopic arm (Bu), a lower telescopic arm (Bd) and an inductor (Lb). The upper telescopic arm (Bu) and the lower telescopic arm (Bd) are respectively formed by cascading connection of a plurality of units. The converter bridge arm has a simple modular structure, is easy to control, reliable and convenient for starting a high-voltage circuit, has self-balancing voltage sharing effect, and can operate without a transformer and has the characteristic of power bidirectional flow, does not require high-voltage isolation auxiliary power supply, has the advantages of suitability for high-frequency operation and electromagnetic compatibility, and can remarkably reduce the dimension of a filter.