Modular Converter Submodule With Chopper-Protected Battery
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Solution Overview
Problem
Existing power converters are limited in their ability to compensate for reactive power and exchange active power with high-voltage AC networks, as they are not designed to handle high currents during reactive power compensation, which can damage energy storage devices.
Innovation Solution
A power converter with an additional energy store connected to the capacitor unit via a chopper unit, featuring an electronic switch and inductive unit in series, allowing for regulated current flow and protection from high currents, enabling the converter to exchange active power while maintaining voltage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the converter is designed to exchange active power with high-voltage AC networks, then the energy storage capability is improved, but the device becomes vulnerable to high currents during reactive power compensation
Solution Approach 1:
The energy storage system is segmented into two distinct components: a capacitor unit for reactive power compensation and an additional energy store (battery) for active power exchange. This segmentation allows each component to be optimized for its specific function and protected from operating conditions it cannot withstand, particularly protecting the battery from high currents during reactive power compensation events.
Solution Approach 2:
A chopper unit is introduced as an intermediary between the capacitor unit and the additional energy store. This chopper unit regulates current flow and provides protection, preventing high currents from damaging the additional energy store while enabling controlled energy transfer between the two storage devices and the AC network.
2Device complexity
If the converter uses only capacitor units for energy storage, then the device structure is simpler, but the converter can only perform reactive power compensation and cannot exchange active power
Solution Approach 1:
The converter is designed with multi-functionality by combining a capacitor unit and an additional energy store. This configuration enables the single device to perform both reactive power compensation (using the capacitor) and active power exchange (using the additional energy store), making it a universal solution for both grid support functions without requiring separate dedicated devices.
3Device complexity
If the converter valve uses submodules with limited energy storage in capacitor units, then the device complexity is reduced, but the converter is only suitable for reactive power compensation
Solution Approach 1:
The invention merges two types of energy storage devices (capacitor unit and additional energy store) within the submodule structure. This combination allows the converter to achieve both reactive power compensation and active power exchange capabilities, significantly enhancing productivity and functionality while maintaining a structured modular design that builds upon rather than completely replaces existing submodule architectures.
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
The solution allows for effective reactive power compensation and active power exchange with high-voltage networks, protecting energy storage devices from high currents and maintaining voltage stability, thus addressing the limitations of existing converters.
Implementation Method 1
an inductive unit (11) arranged in series with the electronic switch (12), wherein the electronic switch (12) has two turn-off power semiconductors (13) which are arranged in series with one another and have current flow directions in opposite directions
Implementation Method 2
the additional energy store (9) being connected to the capacitor unit (3) via a chopper unit (10), the chopper unit (10) having means for regulating the current flow between the capacitor unit (3) and the additional energy store (9)
Data Source
Figure 1~4
Figure 5~6
AI summary
In order to provide a submodule (1) for forming a multi-stage power converter for electric energy distribution and transmission, comprising a capacitor unit (3) and a power semiconductor circuit (4) having power semiconductors (5) that can be switched off, wherein the capacitor unit (3) and the power semiconductor circuit (4) are interconnected such that, depending on the actuation of the power semiconductors (5) of the power semiconductor circuit, at least the voltage released at the capacitor unit (3) or a zero voltage can be generated at the output terminals (7, 8) of the submodule (1), said submodule not only being able to compensate for reactive power, but exchanging active power with the connecting alternating current network, an additional energy storage device (9) is proposed, which is connected to the capacitor unit (3) by way of a chopper unit (10), wherein the chopper unit (10) comprises means for regulating the current flow between the additional energy storage device (9) and the capacitor unit (3).