Converter Submodule Circuit With Split Inductor and Crowbar Protection
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Solution Overview
Problem
Converter systems face significant destruction and safety risks due to high current discharges when power semiconductor switches fail, leading to potential chain reactions and hazardous conditions.
Innovation Solution
A submodule design incorporating a series-connected switching circuit with an energy storage circuit, split inductor, and crowbar thyristor system to manage and dissipate excess energy, reducing the risk of catastrophic failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the capacity of the energy storage device is increased, then the energy storage capacity of the submodule is improved, but the destruction risk and housing strength requirements worsen due to higher discharge currents in fault conditions
Solution Approach 1:
A current limiting inductor is introduced as an intermediary element between the energy storage device and the power semiconductor switches. This inductor acts as a mediator that allows normal energy transfer while blocking excessive discharge currents during faults, thus enabling higher energy storage capacity without proportionally increasing destruction risk.
Solution Approach 2:
The submodule housing is designed with enhanced strength and protection measures in advance to withstand the expected increased mechanical stress and thermal loads from higher energy storage devices. This preparatory reinforcement cushions against potential destruction risks before faults occur.
2Use of energy by moving object
If the capacity of the energy storage device is increased, then the energy storage capacity is improved, but the housing strength requirements increase leading to higher device complexity
Solution Approach 1:
The current limiting inductor serves as a protective intermediary that reduces the peak discharge current magnitude. This allows the housing to be designed with moderate strength requirements while still protecting against damage, even when using high-capacity energy storage devices.
3Reliability
If the housing strength is increased to prevent hazardous failures, then the safety during operation is improved, but the energy storage capacity is limited
Solution Approach 1:
The current limiting inductor is positioned between the energy storage device and the switching circuit to act as a protective mediator. It allows the use of higher energy storage capacities while maintaining safety, as the inductor naturally limits fault currents without requiring excessive housing reinforcement.
Solution Approach 2:
The inductance value of the current limiting inductor is carefully selected to provide adequate current limitation during faults while minimizing impact on normal operation. By optimizing this parameter, the system achieves both high energy storage capacity and operational safety.
4Object-affected harmful factors
If current limiting measures are implemented, then the destruction risk is reduced, but the device complexity increases
Solution Approach 1:
A single current limiting inductor is introduced as a simple intermediary element that provides passive current limitation during faults. This straightforward approach reduces destruction risk without significantly increasing device complexity, as the inductor integrates seamlessly into the existing circuit topology.
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 submodule effectively limits current surges and prevents hazardous explosions, allowing for increased energy storage capacity while maintaining system safety.
Implementation Method 1
a split inductor, which is connected in series with the first capacitor, and which is adapted for limiting current amplitudes
Implementation Method 2
a first crowbar, which is connected in parallel with the first capacitor and which is adapted to dissipate energy from the first capacitor
Data Source
Figure 1~2
Figure 3
AI summary
Submodule (10) for a converter system (100) comprising a first connecting terminal (11), a second connecting terminal (12), a switching circuit (20) with a first power semiconductor switch (21) and a second power semiconductor switch (22), which are connected in series and can be turned on and off. The first connecting terminal (11) is connected to the node between the first power semiconductor switch (21) and the second power semiconductor switch (22). The submodule (10) further comprises an energy storage circuit (30) connected in parallel with the switching circuit (20): The energy storage circuit (30) comprises a first capacitor (31) with a first capacitance (311), a split inductor (32), which is connected in series with the first capacitor (31) and adapted for limiting current amplitudes and a second capacitor (41) with a second capacitance (411) acting as part of a commutating system (40), wherein the second capacitor (41) is arranged in parallel to the switching circuit (20) and in parallel to the first capacitor (31) and the split inductor (32). The submodule (10) further comprising a first crowbar (50), which is connected in parallel with the first capacitor (31) and which is adapted to dissipate energy from the first capacitor (31), comprising a first bypass thyristor (51) .