Power Filter LCR Peak Compensation for LC Resonance Gain Dips

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Solution Overview

Problem

The instability of the control loop in power filters due to the influence of LC resonance frequency makes loop compensation difficult, especially with the use of low-inductance inductors and polymer capacitors, which shift gain dips to higher frequencies and deepen them, complicating the compensation process.

Innovation Solution

A power filter design incorporating an overvoltage protection circuit with a peak compensation circuit, implemented as an LCR parallel resonance circuit, generates a gain peak at the LC resonance frequency to counteract the gain dip, using an equivalent inductance circuit and RC components to form an LCR parallel resonance circuit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an LC filter is used in the power filter, then filtering performance is improved, but stability of the control loop deteriorates due to gain dip at resonance frequency

Engineering Contradiction:
Improvefiltering performanceVSAvoidcontrol loop stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent converts the harmful gain dip at LC resonance frequency into a beneficial feature by introducing a peak compensation circuit that generates a gain peak at the same frequency. This compensates for the gain dip, maintaining control loop stability while preserving the filtering performance of the LC filter. The harmful effect of the gain dip is transformed into a useful compensation mechanism.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The peak compensation circuit acts as an intermediary element between the LC filter and the control loop. It mediates the interaction by introducing a gain peak that counteracts the gain dip caused by the LC filter, thereby enabling stable control loop operation without compromising filtering performance.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If low-inductance inductors and polymer capacitors are used, then filtering performance is improved, but control loop compensation becomes more difficult due to deeper and higher frequency gain dips

Engineering Contradiction:
Improvefiltering performanceVSAvoidcompensation circuit complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent addresses the challenge of deeper and higher frequency gain dips by adjusting the parameters of the peak compensation circuit. By tuning the resonance frequency and gain of the compensation circuit to match the characteristics of the LC filter formed by low-inductance inductors and polymer capacitors, the patent achieves effective compensation without increasing overall system complexity.

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If peak compensation circuit is added to compensate for gain dip, then control loop stability is improved, but device complexity increases

Engineering Contradiction:
Improvecontrol loop stabilityVSAvoidcircuit structure complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent merges the peak compensation circuit with the existing control loop structure of the power filter. By integrating the compensation functionality into the existing circuit architecture rather than adding completely separate components, the patent achieves control loop stability improvement while minimizing the increase in device complexity.

Inventive Principle:
Principle #5Merging (Combining)

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 LCR parallel resonance circuit effectively compensates for the gain dip, stabilizing the control loop without requiring a high crossover frequency, thus maintaining loop stability and simplifying the compensation process.

Implementation Method 1

The peak compensation circuit is implemented as an LCR parallel resonance circuit

Methodology Applied
Scientific EffectLCR parallel resonance: Resonance

Data Source

PatentEP4152541B1Power filter
Publication Date: 2025.10.15 HARMAN BECKER AUTOMOTIVE SYST GMBH
  • EP4152541B1 patent drawingFigure 1~2
  • EP4152541B1 patent drawingFigure 3~4
  • EP4152541B1 patent drawingFigure 5A~5B

AI summary

The present disclosure provides a power filter. The power filter may include an overvoltage protection circuit and an LC filter circuit connected to the overvoltage protection circuit, wherein the overvoltage protection circuit includes a voltage regulator and a peak compensation circuit. The peak compensation circuit is configured to generate a gain peak at a resonance frequency of the LC filter circuit, so as to compensate for a gain dip at the voltage regulator stage occurring at the resonance frequency of the LC filter circuit.