Voltage Source Converter Monopolar Operation Without Transformer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing Voltage Source Converters require transformers for monopolar operation, leading to increased costs and complexity, even when high voltages do not necessitate transformer usage.
Innovation Solution
A Voltage Source Converter design where one pole is connected to a high voltage potential and the other to a neutral potential, allowing voltage pulses to be both positive and negative, enabling monopolar operation without a transformer by using a series connection of switching cells and H-bridges, which deliver voltage pulses relative to a neutral potential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a transformer is used for monopolar operation, then the converter can operate in monopolar mode, but equipment costs and device complexity increase
Solution Approach 1:
The invention extracts and eliminates the transformer component from the monopolar operation configuration by introducing a neutral potential pole and associated switching arrangement that directly provides the necessary reference potential without requiring electromagnetic transformation
Solution Approach 2:
The neutral potential pole acts as an intermediary element that provides the reference potential for monopolar operation, replacing the transformer's function of establishing a neutral reference point while avoiding the complexity and cost of transformer equipment
2Adaptability or versatility
If a transformer is used for monopolar operation, then the converter can operate in monopolar mode, but equipment costs increase
Solution Approach 1:
The invention removes the expensive transformer component from the monopolar operation configuration by using a direct electrical connection through the neutral potential pole and switching cells, significantly reducing equipment costs while maintaining operational versatility
3Stress or pressure
If multiple switching cells are connected in series for high voltage, then high voltage capability is achieved, but the number of semiconductor devices and complexity increase
Solution Approach 1:
The switching cells serve multiple functions simultaneously: they provide voltage division for high voltage handling, create the neutral potential reference, and enable both bipolar and monopolar operation modes, thereby reducing the need for additional dedicated components
Solution Approach 2:
The invention introduces asymmetry in the potential configuration by designating one pole as high voltage potential and the other as neutral potential, allowing optimized switching cell arrangements that reduce overall system complexity compared to symmetric bipolar configurations
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration allows for cost-effective monopolar operation without transformers, reducing equipment costs and maintaining efficient power transmission with stable energy storage capacitors, while achieving desired alternating voltage shapes and levels.
Implementation Method 1
each said switching cell having on one hand at least two semiconductor assemblies connected in series and having each a semiconductor device of turn-off type and a free-wheeling diode connected in parallel therewith and on the other at least one energy storing capacitor
Implementation Method 2
each said switching cell having on one hand at least two semiconductor assemblies connected in series and having each a semiconductor device of turn-off type and a free-wheeling diode connected in parallel therewith
Data Source
Figure 1
Figure 2~4
Figure 5~7
AI summary
A Voltage Source Converter of M2LC-type has a series connection of switching cells (7), in which each switching cell has on one hand at least two semiconductor assemblies connected in series and having each a semiconductor device of turn-off type and a free-wheeling diode connected in parallel therewith and on the other at least one energy storing capacitor (20). The series connection of switching cells has one first end (61) connected to a direct voltage pole (5) on high voltage potential and an opposite end (62) connected to a phase output (10) of the converter. An arrangement (70) is configured to connect the phase output (10) to another said pole (6) on neutral voltage potential on a direct voltage side of the converter and to deliver voltage pulses to said phase output being both positive and negative with respect to said neutral potential.