Mixed-Core Inductor Switching Regulator for High-Frequency Ripple
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Solution Overview
Problem
Conventional switching regulators face inefficiency and reliability issues due to heat loss when operating at high switching frequencies, which limits their ability to increase switching frequencies effectively.
Innovation Solution
An integrated switching regulator device with a low-pass filter comprising multiple LC stages, where the first stage uses an air-cored inductor to manage AC-related heat and subsequent stages use non-air-cored inductors, such as ferrite or metal composite cores, to minimize heat loss and maintain filtering efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the switching frequency of a regulator is increased from 1 MHz to 10 MHz, then the ripple attenuation capability is improved, but the temperature of the inductor core increases by approximately ten fold causing excessive heat loss
Solution Approach 1:
The low-pass filter is divided into multiple LC stages with different inductor core types. The first stage uses an air-cored inductor to handle high-frequency switching without excessive heat generation, while subsequent stages use non-air-cored inductors for additional filtering. This segmentation allows the system to operate at high switching frequencies (10 MHz) without the inductor core becoming too hot, as the air-cored inductor minimizes core losses at high frequencies.
Solution Approach 2:
Different parts of the filtering system are assigned different inductor core qualities suited to their specific functions. The first LC stage requires an inductor that can handle high-frequency AC content without excessive heating, so an air-cored inductor is used. Subsequent stages can use non-air-cored inductors where the AC content is already reduced. This local differentiation of quality allows the system to achieve both high switching frequency operation and effective ripple attenuation.
2Productivity
If the switching frequency is increased to improve regulator performance, then the efficiency and reliability deteriorate due to increased heat loss in the inductor
Solution Approach 1:
The filtering function is segmented into multiple stages with the first stage using an air-cored inductor specifically designed to handle high-frequency operation. This segmentation enables the regulator to operate at high switching frequencies (improving productivity) while the air-cored inductor prevents excessive heat generation that would compromise reliability. The subsequent non-air-cored stages provide additional filtering without bearing the full burden of high-frequency AC content.
3Measurement precision
If a low-pass filter is used to attenuate ripple, then the filtering effectiveness is improved, but the inductor core becomes too hot due to higher frequency AC content
Solution Approach 1:
The low-pass filter is segmented into multiple LC stages where the first stage employs an air-cored inductor that does not suffer from core heating issues at high frequencies. This allows the filter to effectively attenuate ripple from high-frequency switching without the inductor core becoming excessively hot. Subsequent stages use non-air-cored inductors where the AC content has already been significantly reduced by the first stage.
Solution Approach 2:
The first LC stage is specifically designed with an air-cored inductor quality that is optimal for handling high-frequency AC content without heating. This local quality assignment to the first stage allows it to perform the demanding task of initial ripple filtering at high frequencies, while subsequent stages can use different inductor types where the thermal burden is reduced.
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 configuration allows the switching regulator to operate at high switching frequencies with reduced inductor core heating, maintaining efficiency and reliability by distributing heat loss and minimizing the overall area required for the filter, while effectively attenuating ripple.
Implementation Method 1
the inductor of the first LC stage comprises an air cored inductor
Implementation Method 2
the inductor of each subsequent LC stage comprises a non-air cored inductor... the non-air cored inductor comprises an inductor comprising a ferrite core... the non-air cored inductor comprises an inductor comprising a metal composite core
Implementation Method 3
a low pass filter coupled to the switching regulator configured to filter the pulsed voltage
Data Source
AI summary
An integrated switching regulator device has a switching mode regulator comprising an input voltage source and a switching circuit coupled to the input voltage source configured to generate a pulsed voltage from the input voltage. A low pass filter is coupled to the switching regulator and is configured to filter the pulsed voltage to provide a regulated voltage to a load. The low pass filter comprises at least two LC stages, wherein the first LC stage comprises an air cored inductor and each subsequent LC stage comprises a non-air cored inductor. The switching circuit comprises two or more switching elements configurable to operate at a switching frequency of several megahertz.