Power Converter DC Fault Detection Using Differential Current
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power electronics converters in aerospace applications are vulnerable to DC-side faults, which can cause large fault currents that damage diodes, particularly when MOSFETs are used, due to the rapid discharge of the DC link capacitor and AC-side current flow, leading to uncontrolled diode conduction.
Innovation Solution
A power electronics converter with semiconductor switches, a differential current sensor, and a controller that detects fault conditions by measuring differential current and voltage thresholds, preventing current flow to the DC network, and includes features like reverse-biased diodes and gate driver circuits to protect the switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional power electronics converters are used in aerospace applications, then the system can provide electrical power conversion, but the converters are vulnerable to DC-side faults causing large fault currents that damage diodes
Solution Approach 1:
The controller continuously monitors differential current through the DC terminals and detects fault conditions before they cause damage. When a fault is detected (current peak exceeding threshold), the controller immediately actuates the semiconductor switches to open the current pathway, preventing the fault current from damaging the diodes. This preliminary detection and action prevents the harmful effect before it occurs.
Solution Approach 2:
The patent introduces an intermediary protection mechanism consisting of the differential current sensor and controller that mediates between the fault condition and the diodes. The sensor detects the fault current, and the controller uses the semiconductor switches to control the current flow, acting as an intermediary that protects the diodes from direct exposure to damaging fault currents.
2Reliability
If additional protection components are added to protect against fault currents, then diode protection is improved, but device complexity increases
Solution Approach 1:
The semiconductor switches serve multiple functions: they perform the primary power conversion function in the converter, and simultaneously serve as protection devices that can rapidly open to prevent fault current damage. This multi-functionality eliminates the need for separate protection components, maintaining diode protection while avoiding increased device complexity.
Solution Approach 2:
The converter's existing semiconductor switches and control system provide self-protection against fault currents. The differential current sensor monitors the system, and when a fault is detected, the controller automatically actuates the switches to protect the diodes. This self-service approach uses the converter's own components for protection rather than adding external protection devices.
Data Source
Figure 1
Figure 2A~2B
Figure 3A
AI summary
A power electronics converter 1020 comprising: an input terminal; first and second DC output terminals 1003, 1004; a branch comprising first and second semiconductor switches connected in series between the first and second DC output terminals 1003, 1004, the input terminal connected to a node between the first and second semiconductor switches; a DC link capacitor 1008 connected between the first and second DC output terminals 1003, 1004; a differential current sensor 1009 arranged to measure a differential current signal through the first or second DC terminals 1003, 1004; and a controller 1040 configured to provide switching signals to each of the first and second switches of the power electronics converter 1020, wherein the controller 1040 is further configured to detect a fault in a DC network 1030 connected between the first and second DC output terminals 1003, 1004 upon detection of a peak in an output from the differential current sensor 1009.