Power Converter Submodule Fault Bypass via Semiconductor Breakdown
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Solution Overview
Problem
Existing power converter systems face challenges in efficiently bypassing faulty submodules without causing arcing faults or explosions, leading to system shutdown and potential damage to other components.
Innovation Solution
A method that selectively identifies and breaks down specific power semiconductor switches to create a durable, stable low-impedance short-circuit path between AC voltage terminals of a faulty submodule, using existing switches and avoiding additional components, thereby preventing fault propagation and ensuring continuous system operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional bypass components are added to create a short-circuit path for faulty submodules, then the reliability of continuous system operation is improved, but the device complexity increases
Solution Approach 1:
The power semiconductor switches in the bridge circuit are designed to serve dual functions: normal power conversion operations and fault bypass operations. When a submodule fails, existing switches are repurposed to create a short-circuit path, eliminating the need for dedicated bypass components and reducing overall system complexity while maintaining reliability
Solution Approach 2:
The faulty submodule uses its own existing power semiconductor switches to create the bypass path rather than relying on external components. The switches within the submodule itself perform the dual role of normal operation and fault protection, making the system self-sufficient for fault handling
2Reliability
If a durable short-circuit path is established through power semiconductor switch breakdown, then the reliability of fault isolation is improved, but the loss of semiconductor components increases
Solution Approach 1:
The faulty submodule is electrically isolated from the series-connected bridge circuit by establishing a low-impedance short-circuit path across its terminals. This extracts the fault from the main circuit, preventing it from affecting other submodules and allowing the healthy portions of the system to continue operating
Solution Approach 2:
The system accepts that one power semiconductor switch may need to be sacrificed (broken down) to create the bypass path, but this loss is acceptable compared to the value of maintaining continuous operation of the entire high-power converter system. The cost of one failed switch is much lower than the cost of complete system shutdown
3Speed
If fast-acting mechanical switches are used to create a bypass path, then the speed of fault response is improved, but the risk of arcing faults and explosions increases
Solution Approach 1:
The invention replaces mechanical switch-based bypass systems with electronically controlled power semiconductor switches. These solid-state switches provide equally fast response times without the mechanical contact issues that cause arcing and explosions, eliminating the harmful effects associated with mechanical switching during fault conditions
Solution Approach 2:
The control system acts as an intermediary that manages the switching operations during faults. By carefully controlling the timing and sequence of switch operations, the system achieves fast fault response while avoiding the dangerous arcing that occurs with uncontrolled mechanical switching
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 approach allows for continuous operation of power converters by establishing a reliable short-circuit path within the submodule, reducing the risk of arcing faults and explosions, and minimizing damage to other components, while eliminating the need for additional bypass components.
Implementation Method 1
driving the one or two power semiconductor switches selected as the bypass device or devices by a modified driving voltage compared to normal operation to cause the selected one or two power semiconductor switches to break down in order to provide a durable, stable, low impedance short-circuit path
Data Source
AI summary
A method of short-circuiting a faulty submodule for a voltage-source power converter is disclosed. The submodule is based on a full-bridge, asymmetric full-bridge or half-bridge circuit design having power semiconductor switches with anti-parallel freewheeling diodes and optionally non-controllable semiconductor valves. The method 36 includes identifying a faulty semiconductor device and determining a failure mode selected from a short-circuit failure mode and an open circuit failure mode. The method further includes selecting a minimum number of power semiconductor switches suitable to provide a bypass path through the submodule depending on the identified faulty semiconductor device and the determined failure mode and driving the selected power semiconductor switches by a modified driving voltage compared to normal operation to cause them to break down in order to provide a durable, stable, low impedance short-circuit path between the AC voltage terminals of the submodule. A power converter comprising a series connection of such submodules and supporting the method of short-circuiting a faulty submodule is also disclosed.