Current-Source Power Converter Auxiliary Switch Startup Protection
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Solution Overview
Problem
Current source power converters using normally closed field effect transistors face challenges in avoiding short-circuiting during startup and auxiliary power supply malfunctions, requiring oversized relays to manage network currents and voltages.
Innovation Solution
Incorporating a normally open auxiliary switch in series with the switching arms and a protection system against overvoltages, along with a malfunction detection mechanism, to control the flow of current and prevent short-circuiting without using oversized components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oversized relays are used to control network current and voltage during startup and malfunctions, then network short-circuiting is prevented, but device complexity and component size increase
Solution Approach 1:
The protection function is segmented between the auxiliary switch (handling startup and fault isolation) and the normally closed transistors (handling normal operation). This segmentation allows each component to be optimally sized for its specific function rather than requiring oversized relays to handle all scenarios.
Solution Approach 2:
The auxiliary switch acts as an intermediary component that bridges the gap between the current source and the normally closed transistors during startup and fault conditions. It provides controlled current flow without requiring the main protection relays to be oversized.
2Productivity
If normally closed field effect transistors are used in the rectifier module, then the converter operates efficiently with permanent conduction, but network short-circuiting risk increases during startup and auxiliary power supply malfunctions
Solution Approach 1:
The auxiliary switch is activated in advance before the normally closed transistors are energized during startup. This preliminary action ensures that current flow is controlled and prevented from short-circuiting the network before the transistors become conductive.
Solution Approach 2:
The control system monitors the state of the auxiliary power supply and transistor gates, providing feedback control to the auxiliary switch. This ensures the auxiliary switch remains closed only when conditions are safe, preventing short-circuits while allowing efficient operation when conditions permit.
3Reliability
If three oversized relays are positioned on input phases to support all network current and voltage, then network protection is ensured, but component cost and device complexity increase
Solution Approach 1:
The protection function is segmented between the auxiliary switch (handling startup and fault isolation) and the normally closed transistors (handling normal operation). This segmentation allows each component to be optimally sized for its specific function rather than requiring oversized relays to handle all scenarios.
Solution Approach 2:
The auxiliary switch performs multiple functions: it controls startup current flow, provides fault isolation, and enables safe operation with normally closed transistors. This multi-functionality eliminates the need for separate oversized relays for each protection scenario.
Data Source
Figure 1
Figure 2A~2B
AI summary
The invention relates to a current-source power converter using, in its rectifier module (20) and/or its inverter module, switching arms equipped with normally closed field-effect transistors (T1-T6, Q1-Q6), each controlled by a gate driver (CT1, CT2). The invention is distinguished by the inclusion of a normally open auxiliary switch (SW) positioned in series with the switching arms and connected to the positive line (10) of the power bus. This auxiliary switch is intended to prevent the network (R) from being short-circuited during startup or in the event of malfunctions in the auxiliary power supply (AUX).