Switching Circuit Snubber Layout for Lower-Voltage Ringing Damping
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Solution Overview
Problem
Switching circuits for voltage source converters face challenges with high voltage levels, requiring large and bulky snubber components to dampen ringing, which is inefficient and costly.
Innovation Solution
A switching circuit design that lowers the voltage rating of snubber components by using series-connected switches and capacitors with strategically placed snubber resistors and capacitors, where the values are determined based on stray capacitance, damping factor, and loop stray inductance to achieve efficient damping without needing to handle full DC voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If snubber components are designed to handle high voltage levels of switches, then reliability is improved, but device size and cost increase
Solution Approach 1:
The circuit is segmented into two functional parts: the string of switches handling high voltage, and the snubber components handling only voltage fluctuations. By connecting snubber components in parallel with conductors that interconnect switches with capacitors, the snubbers are isolated from the full DC voltage and only experience local voltage variations, enabling the use of lower-rated, smaller components while maintaining damping effectiveness.
2Volume of stationary object
If snubber components are made smaller with lower voltage ratings, then device size and cost are reduced, but ability to dampen ringing at high voltage levels may be compromised
Solution Approach 1:
Conductors serve as intermediaries between the high-voltage switch string and the low-voltage-rated snubber components. These conductors interconnect the switches with capacitors and allow the snubbers to dampen ringing currents without being directly exposed to the full DC voltage, effectively transferring the damping function to components with lower voltage ratings.
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 design allows for smaller, lower-rated snubber components that effectively dampen ringing, reducing size and cost while maintaining efficient operation, as they only need to withstand voltage fluctuations across half the loop inductance.
Implementation Method 1
a first string of components connected between the first end of the string of series-connected switches and the first end of the string of capacitors, and a second string of components connected between the second end of the string of series-connected switches and the second end of the string of capacitors, wherein the first string of components comprises at least one snubber component for the first switch and the second string of components comprises at least one snubber component for the second switch
Implementation Method 2
the first string of components comprises a first snubber resistor and a first snubber capacitor for the first switch and the second string of components comprises a second snubber resistor and a second snubber capacitor for the second switch
Data Source
Figure 1~2
Figure 3~4
Figure 5a~5b
AI summary
The invention concerns a switching circuit (15) as or for a voltage source converter comprising a string of series-connected switches comprising a first and a second switch (S1, S2), a string of capacitors comprising at least one capacitor (C1), a first conductor (16) interconnecting a first end of the string of switches with a first end of the string of capacitors, a second conductor (18) interconnecting a second end of the string of switches with a second end of the string of capacitors, a first string of components connected between the first end of the string of switches and the first end of the string of capacitors and a second string of components connected between the second end of the string of switches and the second end of the string of capacitors, wherein the first string of components comprises at least one snubber component (20, 22) for the first switch (S1) and the second string of components comprises at least one snubber component (24, 26) for the second switch (S2).