Chain-Link Module Energy Balancing for Voltage Source Converters
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Solution Overview
Problem
In voltage source converters, achieving efficient and reliable operation of chain-link converters is hindered by the difficulty in balancing energies stored across multiple energy storage devices, leading to inefficiencies and increased losses.
Innovation Solution
A chain-link module with series-connected switching elements and energy storage devices, each with an auxiliary power supply unit and a modulation controller, allows for proportional energy modulation and balancing through a selector module that compares energy storage values to determine energy conduit operation, ensuring balanced energy distribution across devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple energy storage devices are connected in series to provide higher voltage, then the voltage output capability is improved, but the difficulty in balancing energy distribution across devices increases
Solution Approach 1:
The patent divides the energy storage system into multiple independently controllable modules, each with its own auxiliary power supply unit and modulation controller. This segmentation allows individual energy balancing control for each device while maintaining series connection for high voltage output, resolving the contradiction between voltage capability and balancing difficulty.
Solution Approach 2:
The patent implements feedback control through modulation controllers that monitor energy storage levels and adjust the operation of auxiliary power supply units accordingly. This feedback mechanism enables automatic energy balancing across series-connected devices, reducing the complexity of manual balancing while maintaining high voltage output capability.
2Power
If auxiliary power supply units are connected in parallel with multiple energy storage devices, then the energy supply capability is improved, but the voltage rating requirements and design difficulty increase
Solution Approach 1:
Instead of connecting one auxiliary power supply unit in parallel with multiple series-connected energy storage devices (which would require high voltage rating), the patent segments the system so that each energy storage device has its own auxiliary power supply unit connected in parallel. This reduces the voltage rating requirement for each auxiliary unit while collectively providing sufficient energy supply capability.
Solution Approach 2:
The patent introduces modulation controllers as intermediary devices that manage the energy flow between auxiliary power supply units and the main system. These controllers simplify the design of auxiliary power supply units by handling the complexity of energy distribution and balancing, allowing each unit to operate at lower voltage ratings while collectively supporting the high-voltage series-connected energy storage system.
3Ease of operation
If energy is not balanced across energy storage devices, then operational simplicity is maintained, but efficiency and reliability decrease due to increased losses
Solution Approach 1:
The patent enables the energy storage system to self-balance through automated feedback control mechanisms. Each modulation controller independently monitors and adjusts energy distribution to maintain balance across devices, eliminating the need for complex manual intervention while improving efficiency and reliability. This self-service approach resolves the contradiction by automating the balancing process.
Data Source
AI summary
In the field of chain-link modules for voltage source converters, there is a need for an improved chain-link module. A chain-link module, for connection in series with other chain-link modules to form a chain-link converter selectively operable to provide a stepped variable voltage source within a voltage source converter, includes at least one pair of series-connected switching elements that are connected in parallel with a number of series-connected energy storage devices. Each energy storage device has an auxiliary power supply unit connected in parallel therewith to source energy therefrom for supply to an auxiliary chain-link module control circuit. The chain-link module also includes a modulation controller which is interconnected between each auxiliary power supply unit and the auxiliary chain-link module control circuit. The modulation controller is configured to modulate the proportion of energy supplied to the auxiliary chain-link module control circuit by each auxiliary power supply unit.