Power Filter Peak Compensation for LC Resonance Stability
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Solution Overview
Problem
The instability of the control loop in power filters due to the influence of LC resonance frequency, which complicates loop compensation, especially with the use of low-inductance inductors and polymer capacitors that shift gain dips to higher frequencies and deepen them.
Innovation Solution
A power filter design incorporating an overvoltage protection circuit with a peak compensation circuit, specifically an LCR parallel resonance circuit, to generate a gain peak at the LC filter's resonance frequency, compensating for the gain dip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an LC filter is used in the power filter, then filtering performance is improved, but the control loop becomes unstable at the resonance frequency of the LC
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 attenuation caused by the LC filter, transforming the instability problem into a solution that maintains both filtering performance and control loop stability.
Solution Approach 2:
The patent modifies the frequency response parameters of the control loop by adding a peak compensation circuit with specific LCR components. By adjusting the inductance, capacitance, and resistance values of the compensation circuit, the gain peak is positioned at the LC resonance frequency to counteract the gain dip, thereby changing the overall frequency response characteristics to achieve stability.
2Device complexity
If low-inductance inductors and polymer capacitors are used, then the power filter size and cost are reduced, but the gain dip shifts to higher frequencies and deepens, complicating loop compensation
Solution Approach 1:
The patent addresses the deepened and high-frequency gain dip by designing a peak compensation circuit specifically tuned to counteract these effects. The compensation circuit generates a gain peak at the same high frequency where the dip occurs, converting the problematic deep dip into a flattened frequency response that is easier to compensate for in the control loop.
3Reliability
If the open-loop gain is increased excessively to compensate for the gain dip, then the gain dip is compensated, but the system becomes more sensitive to noise and instability
Solution Approach 1:
Instead of increasing the open-loop gain across all frequencies, the patent applies local compensation by introducing a peak compensation circuit that specifically targets the frequency range where the gain dip occurs. This localized approach adds gain only where needed (at the resonance frequency) without excessively amplifying noise and instability across the entire frequency spectrum.
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 stabilizes the control loop by generating a gain peak to counteract the dip, allowing for easier and cost-effective loop compensation without increasing the open-loop gain excessively, thus maintaining stability even with high-frequency dips.
Implementation Method 1
the peak compensation circuit is configured to generate a gain peak at a resonance frequency of the LC filter circuit
Implementation Method 2
the peak compensation circuit may be implemented as an LCR parallel resonance circuit
Data Source
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.