Power Converter Protection Circuit for DC Fault Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional DC/AC inverter systems face challenges in effectively stopping DC fault current flow, with high voltage/high current DC circuit breakers being inadequate, and existing protection circuits increasing design complexity and cost without fully protecting against faults like DC terminal shorts or phase leg shoot-throughs.
Innovation Solution
A power converter design incorporating a protection circuit with MOSFET switches and a resistor line to absorb energy and provide ringing damping, allowing for simultaneous switching of switches between DC link capacitors to isolate energy sources during overvoltage or short circuits, reducing the need for separate protection circuits in each device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high voltage/high current DC circuit breakers are used to stop DC fault current flow, then protection capability is improved, but device complexity and cost increase significantly
Solution Approach 1:
The DC link capacitor is divided into multiple series-connected capacitors with individual protection circuits for each, rather than using a single complex DC circuit breaker. This segmentation allows simpler, more cost-effective protection while maintaining overall system reliability.
Solution Approach 2:
Protection switches are introduced as intermediary components between the DC link capacitors and the fault sources. These switches act as mediators that can rapidly isolate faults without requiring complex high-voltage DC circuit breakers, thereby reducing device complexity while maintaining protection capability.
2Reliability
If device-level protection circuits such as current desaturation protection are applied in all devices, then protection coverage is improved, but design complexity and system cost increase
Solution Approach 1:
The protection circuit is designed as a universal multi-functional system that can handle multiple fault types (DC terminal shorts, phase leg shoot-throughs, overvoltage conditions) through a common architecture. This eliminates the need for separate dedicated protection circuits for each device, reducing design complexity while maintaining comprehensive protection coverage.
Solution Approach 2:
Multiple protection functions are merged into a single integrated protection circuit architecture. Instead of implementing separate protection circuits in each device, the invention combines overvoltage protection, short-circuit protection, and fault isolation functions into a unified system that operates across all devices collectively.
3Reliability
If protection circuits are added to protect against DC terminal shorts and phase leg shoot-throughs, then protection effectiveness is improved, but design complexity increases
Solution Approach 1:
The protection switches are pre-positioned in series with each DC link capacitor, ready to rapidly disconnect upon fault detection. This preliminary arrangement allows immediate fault isolation without requiring complex real-time reconfiguration, thereby improving protection effectiveness while keeping the design relatively simple.
Solution Approach 2:
The protection circuit incorporates feedback mechanisms that monitor voltage and current conditions across the DC link capacitors. When faults such as DC terminal shorts or phase leg shoot-throughs are detected, the feedback signal triggers the protection switches to open, providing effective protection without requiring overly complex control logic.
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 solution provides fast and effective overvoltage or short circuit protection, reducing device voltage stress and preventing cascaded failures, while simplifying the design and reducing costs by integrating protection functions within a common circuit.
Implementation Method 1
The resistor can be configured to absorb energy and provide ringing damping during a protection transient
Data Source
AI summary
A power converter can include a first line, a second line, a capacitor line disposed between the first line and the second line, a first capacitor and a second capacitor connected to the capacitor line in series between the first line and the second line, a midpoint line connected to a midpoint between the first capacitor and the second capacitor, and a protection circuit disposed between the first capacitor and the second capacitor and configured to provide protection to one or more portions of the power converter.