Parallel Converter Switching to Suppress Loop Interference
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Solution Overview
Problem
High-power converters face challenges in suppressing loop interference due to inconsistent turn-off times of anti-parallel diodes in parallel-connected power electronic devices, leading to voltage differences between connection nodes, which cause interference in voltage sampling circuits, insulation level issues, and electromagnetic interference (EMI).
Innovation Solution
A converter design with a first and second switching set, where the second switching set is turned on after the turn-off time of the first switching set to create a current loop, reducing electrical potential differences between nodes and minimizing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power electronic devices are connected in parallel to achieve high capacity, then the converter capacity is improved, but voltage difference between connection nodes increases due to parasitic inductance and inconsistent diode turn-off times
Solution Approach 1:
The patent applies preliminary action by turning on the second switching set before the first switching set is turned off. This advance action ensures that when the first diodes turn off at different times, the second switching devices are already conducting, providing alternative current paths that prevent voltage differences from developing across the parasitic inductance. The timing relationship is specifically designed so that the second switching set is activated in advance to cover the turn-off transition period.
Solution Approach 2:
The second switching set acts as an intermediary element between the first switching set and the parallel bus. When the first switching devices turn off, the second switching devices provide intermediate current paths that bypass the parasitic inductance issues. This intermediary switching set mediates the current transfer, ensuring smooth transitions without creating harmful voltage differences between parallel connection nodes.
2Power
If power electronic devices are connected in parallel, then the converter capacity is improved, but electromagnetic interference (EMI) increases due to voltage differences affecting other circuits
Solution Approach 1:
By activating the second switching set in advance before the first switching set turns off, the patent prevents the generation of harmful voltage transients that would cause EMI. The preliminary activation ensures that current paths are established before interruption, avoiding sudden changes in current that generate electromagnetic interference.
Solution Approach 2:
The patent converts the potential harm of simultaneous switching off by using the second switching set to deliberately create controlled current paths. The second switching set, turned on in advance, absorbs and redirects the energy that would otherwise create harmful EMI, transforming a potentially problematic switching event into a controlled and beneficial current redistribution process.
3Power
If power electronic devices are connected in parallel, then the converter capacity is improved, but interference to voltage sampling circuits and driving signals increases
Solution Approach 1:
The second switching set is turned on in advance to establish stable current paths before the first switching set turns off. This preliminary action prevents voltage fluctuations and interference that would otherwise corrupt voltage sampling signals and driving signals, ensuring reliable operation of control circuits.
Solution Approach 2:
The second switching set serves as an intermediary that isolates the sensitive voltage sampling and driving signal circuits from the harsh switching transients. By providing alternative current paths, it mediates between the high-power switching events and the low-level control signals, protecting the latter from interference.
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 effectively suppresses loop interference, maintains consistent voltages between nodes, reduces EMI, and enhances the reliability of parallel-connected devices without increasing costs.
Implementation Method 1
a certain voltage difference exists between the nodes a and b
Implementation Method 2
since the parallel bus between the parallel power electronic devices have parasitic inductance
Data Source
AI summary
The invention provides a converter and a method for suppressing loop interference of converter. The converter includes first and second switching sets connected to each other. Each switching set includes a plurality of switching devices. The plurality of second switching devices are configured to be turned on for a first time after the turn-off time of the plurality of first switching devices, such that each of the plurality of second switching devices provides a path for current within the first time to reduce a potential difference between the first end of at least one of the plurality of second switching devices and the first end of the remaining of the plurality of second switching devices.