High Frequency Line Filter Using Capacitive-Resistive Damping
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Solution Overview
Problem
Existing high-frequency network filters for converters are costly and lack compact construction, failing to effectively filter interference signals generated by power electronic switches operating at high switching frequencies.
Innovation Solution
A high-frequency network filter utilizing both Y capacitors and impulse-resistant capacitors in parallel configurations, with ohmic damping resistances, to bridge insulation and filter periodic rectangular impulses, reducing current through Y capacitors and eliminating the need for inductance, thereby achieving efficient filtering with a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional passive filters with network of capacitors, coils and resistances are used, then filtering of interference signals is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts and eliminates the inductance component (coils) from the traditional passive filter network, replacing it with a simplified configuration using only capacitors (Y capacitors and impulse-resistant capacitors) and resistances. This extraction of the disturbing element (inductance) reduces device complexity while maintaining filtering effectiveness for high-frequency interference signals.
Solution Approach 2:
The patent changes the capacitive parameters by introducing both Y capacitors (for insulation bridging) and impulse-resistant capacitors (for handling rectangular impulses) in parallel configuration. This parameter change in capacitance structure enables effective filtering of high-frequency switching signals without requiring inductive components, thereby simplifying the overall filter design.
2Reliability
If Y capacitors are used for insulation bridging, then insulation protection is improved, but tolerance to rectangular impulses deteriorates
Solution Approach 1:
The patent merges two different capacitor types with complementary characteristics: Y capacitors (providing insulation bridging and reliability) and impulse-resistant capacitors (providing tolerance to rectangular impulses). By combining these components in parallel, the filter achieves both insulation protection and impulse tolerance, resolving the contradiction between these two requirements.
Solution Approach 2:
The patent uses a composite capacitor structure combining different capacitor technologies (Y capacitors and impulse-resistant capacitors) to achieve properties that neither component alone could provide. This composite approach enables simultaneous insulation bridging and impulse tolerance, effectively resolving the technical contradiction.
3Volume of moving object
If compact construction is achieved by eliminating inductance, then device volume is reduced, but filtering effectiveness for high-frequency signals may deteriorate
Solution Approach 1:
The patent changes the filtering mechanism by relying on capacitive and resistive parameters instead of inductive parameters. The parallel combination of Y capacitors and impulse-resistant capacitors, together with ohmic damping resistances, creates effective high-frequency filtering without requiring inductance, thus achieving compact construction while maintaining filtering effectiveness.
Solution Approach 2:
The patent substitutes the traditional inductive filtering mechanism with a capacitive-resistive filtering system. By replacing inductance (mechanical/magnetic field-based component) with capacitance and resistance (electrical field-based components), the filter achieves compact construction while effectively filtering high-frequency interference signals through electrical parameter optimization.
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
The solution provides effective filtering of high-frequency interference signals with reduced component complexity and cost, ensuring safe operation and compliance with electromagnetic compatibility regulations.
Implementation Method 1
By using both Y capacitors and impulse-resistant capacitors, insulation of the converter can be bridged on the one hand and, on the other hand, can be filtered periodically recurring rectangular impulses according to the switching frequency of the converter
Implementation Method 2
Due to the parallel connection of two Y capacitors, each of which can have the same capacity, the current flowing by the impulse-proof capacitor is at least halved for the Y capacitors
Implementation Method 3
each of the filter paths has an ohmic damping resistance which is connected in series to the parallel circuit from the at least two Y capacitors
Implementation Method 4
Through the filter path, each of the phase connections of the converter is switched to mass
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A high-frequency mains filter (50) for an inverter (30) is proposed. The inverter (30) has three phase terminals (31, 32, 33) for receiving a three-phase AC signal (L1', L2', L3') from a three-phase voltage network (L1, L2, L3) and is configured to convert the received three-phase AC signal (L1', L2', L3') into an output signal (V) for a load. The high-frequency mains filter (50) comprises: a first filter path (51) for forming a conductive connection between a first of the three phase terminals (31) and a ground terminal (PE); a second filter path (52) for forming a conductive connection between a second of the three phase terminals (32) and the ground terminal (PE); and a third filter path (53) for forming a conductive connection between a third of the three phase terminals (33) and the ground terminal (PE).The high-frequency mains filter (50) is characterized by a series connection in each of the three filter paths (51, 52, 53) consisting of a pulse-proof capacitor (Ci1, Ci2, Ci3) and a parallel connection of at least two Y-capacitors (Cy1a-b, Cy2a-b, Cy3a-b).