Converter Sub-Module Auxiliary Circuit for Fault Current Management
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Solution Overview
Problem
Conventional HVDC transmission converters face damage from high fault currents due to the lack of efficient fault current management in sub-modules with half-bridge units, necessitating complex and costly auxiliary circuit configurations.
Innovation Solution
A converter design featuring sub-modules with two half-bridge units and a simplified auxiliary circuit unit comprising a single power semiconductor and diode, allowing fault current to flow into the energy storage units of each half-bridge, thereby blocking or reducing fault currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional auxiliary circuit unit with two diodes and one power semiconductor is used between half-bridge units, then fault current can be blocked or reduced, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts one diode from the conventional auxiliary circuit unit configuration. By removing one diode while maintaining the fault current blocking function through the remaining components (one power semiconductor and one diode), the circuit complexity is reduced without compromising the reliability of fault current management
Solution Approach 2:
The patent uses a simpler auxiliary circuit configuration that requires fewer components, thereby reducing manufacturing cost and device complexity while achieving the same fault current protection function. The simplified design uses only one diode and one power semiconductor instead of two diodes and one power semiconductor
2Reliability
If a conventional auxiliary circuit unit with two diodes and one power semiconductor is used between half-bridge units, then fault current can be blocked or reduced, but the manufacturing cost increases
Solution Approach 1:
The patent extracts one diode from the conventional auxiliary circuit unit, reducing the component count from two diodes to one diode. This extraction directly reduces manufacturing cost while preserving the essential fault current blocking capability through the optimized configuration of remaining components
Solution Approach 2:
The patent adopts a cost-effective auxiliary circuit design by minimizing the number of components. The simplified configuration with one diode and one power semiconductor reduces bill of materials cost and assembly complexity, making the converter more economically viable while maintaining reliability
3Reliability
If multiple diodes are used in the auxiliary circuit unit, then fault current management is achieved, but the device complexity and cost increase
Solution Approach 1:
The patent removes one diode from the auxiliary circuit unit, reducing the quantity of diodes from two to one. This extraction maintains the fault current management function by optimizing the circuit topology, where the remaining diode and power semiconductor work together to achieve the same protective effect with fewer components
Solution Approach 2:
The patent enhances the functionality of the remaining diode and power semiconductor in the auxiliary circuit unit. These components perform multiple roles: normal operation switching, fault current blocking, and energy management. By making the components multi-functional, the patent reduces the total number of diodes needed while maintaining comprehensive fault current management capability
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 proposed configuration simplifies the design, reduces manufacturing costs, and effectively manages fault currents, achieving performance comparable to or exceeding conventional systems while minimizing the number of diodes required.
Implementation Method 1
each of the sub-modules includes a first half-bridge unit including a first energy storage unit... a second half-bridge unit including a second energy storage unit... an auxiliary circuit unit connecting the first half-bridge unit and the second half-bridge unit
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present invention relates to a converter in which a plurality of sub-modules, each including an energy storage unit and power semiconductors, is connected in series to each other, wherein each of the sub-modules is configured by adding a simple and inexpensive auxiliary circuit unit between two half-bridge units, and thus fault current is allowed to flow into the energy storage unit of each half-bridge unit, thereby blocking or reducing the fault current. The present invention provides a converter including a plurality of sub-modules connected in series to each other, wherein each of the sub-modules includes a first half-bridge unit including a first energy storage unit, and a plurality of first power semiconductors connected in parallel to the first energy storage unit and connected in series to each other; a second half-bridge unit including a second energy storage unit, and a plurality of second power semiconductors connected in parallel to the second energy storage unit and connected in series to each other; and an auxiliary circuit unit connecting the first half-bridge unit and the second half-bridge unit; wherein the auxiliary circuit unit includes a single third power semiconductor and a single diode.