Filter Circuit Harmonic Compensation Diode Clamping

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Solution Overview

Problem

Existing filter circuits with harmonic compensation face challenges in simplifying circuit control and reducing costs while effectively addressing harmonic distortion in input currents, leading to instability and potential power supply interruptions.

Innovation Solution

A filter circuit structure utilizing a first diode in series with a second diode as a clamping circuit to increase the voltage across the diodes, preventing negative voltage generation on the freewheeling capacitor and enhancing harmonic compensation, thereby improving the harmonic compensation effect.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a bridge rectifier is used to rectify AC voltage to DC voltage, then DC voltage can be obtained for electronic devices, but the input current contains high harmonic components and the power factor is reduced

Engineering Contradiction:
Improvepower factorVSAvoidharmonic components in input current
Core Design Contradiction:
PowerVSObject-generated harmful factors

Solution Approach 1:

The patent introduces a filter circuit as an intermediary component between the bridge rectifier and the power source. This filter circuit includes capacitors and inductors that act as mediators to compensate harmonic components in the input current, thereby improving the power factor without affecting the rectification function

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the electrical parameters of the input current by using passive electronic components (capacitors and inductors) to compensate harmonic components. This transforms the distorted current waveform into a more sinusoidal waveform, improving the power factor from a degraded state back to an acceptable level

Inventive Principle:
Principle #35Parameter changes

2Object-generated harmful factors

If harmonic compensation is implemented using active control components, then harmonic distortion can be reduced, but circuit complexity and cost increase

Engineering Contradiction:
Improveharmonic distortionVSAvoidcircuit control complexity
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent employs passive electronic components (capacitors and inductors) that automatically compensate harmonic components without requiring external control signals or active management. The circuit self-regulates the harmonic compensation based on the input current characteristics, eliminating the need for complex control logic

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces expensive active control components with inexpensive passive electronic components (capacitors and inductors). These passive components achieve harmonic compensation functionality at a lower cost and with simpler circuit implementation, making the solution economically viable

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Object-generated harmful factors

If harmonic compensation is implemented using active control components, then harmonic distortion can be reduced, but circuit cost increases

Engineering Contradiction:
Improveharmonic distortionVSAvoidcircuit cost
Core Design Contradiction:
Object-generated harmful factorsVSEase of manufacture

Solution Approach 1:

The patent substitutes expensive active control components with inexpensive passive electronic components (capacitors and inductors). These passive components are mass-producible, have simple manufacturing processes, and significantly reduce the overall circuit cost while maintaining effective harmonic compensation functionality

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 effectively reduces harmonic distortion in input currents, stabilizes power systems, and reduces circuit costs by using passive electronic components without the need for active control components, ensuring reliable operation and extended component life.

Implementation Method 1

a first diode in series with a second diode acts as a clamping circuit so that a voltage across the two diodes is greater than a voltage across the bridge rectifying diode

Methodology Applied
Scientific EffectDiode clamping effect: Diode

Implementation Method 2

Filter circuit with harmonic compensation by using passive electronic components to simplify circuit control and reduce circuit cost

Methodology Applied
Scientific EffectHarmonic filtering: Filter (electronic)

Data Source

PatentEP3965276B1Filter circuit with harmonic compensation
Publication Date: 2023.07.05 DELTA ELECTRONICS INC(CN)
  • EP3965276B1 patent drawingFigure 1
  • EP3965276B1 patent drawingFigure 2A
  • EP3965276B1 patent drawingFigure 2B

AI summary

A filter circuit (100) with harmonic compensation is coupled to a bridge rectifying circuit (200) receiving an AC voltage (Vac) and an input capacitor (Cin). The bridge rectifying circuit (200) includes a live wire end (L), a neutral wire end (N), a positive end (A), and a negative end (B). The filter circuit (100) includes a freewheeling capacitor (Cf), a freewheeling switch (10), and a unidirectional switch (D). A first end of the freewheeling capacitor (Cf) is coupled to the live wire end (L). A first end of the freewheeling switch (10) is coupled to a second end of the freewheeling capacitor (Cf), and a second end of the freewheeling switch (10) is coupled to the positive end (A) and the input capacitor (Cin). A first end of the unidirectional switch (D) is coupled to the freewheeling capacitor (Cf) and the freewheeling switch (10), and a second end of the unidirectional switch (D) receives a voltage source (Vs). A first conduction voltage of the freewheeling switch (10) is greater than a second conduction voltage between the live wire end (L) and the positive end (A) of the bridge rectifying circuit (200).