Buck Converter Rate-Limited Switching for Wide Input Stability

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Solution Overview

Problem

Buck converters with wide input voltage ranges (e.g., 90 VDC to 600 VDC) experience instability and susceptibility to load disturbances due to high forward control gain.

Innovation Solution

A method of controlling a buck converter by switching between normal and rate-limited switching modes based on the DC link voltage threshold, where the rate-limited mode is enabled when the DC link voltage exceeds a predetermined high threshold and remains enabled until it drops below a predetermined low threshold.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the buck converter operates with a wide input voltage range (90 VDC to 600 VDC), then the adaptability is improved, but the stability deteriorates due to high forward control gain

Engineering Contradiction:

Improveinput voltage rangeVSAvoidconverter stability

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent implements dynamic switching between two control modes (normal mode and rate-limited mode) based on the input voltage level. The controller dynamically adjusts the control strategy by enabling rate-limited switching mode when the input voltage exceeds a threshold, thereby adapting the system behavior to maintain stability across the wide input voltage range while preserving adaptability.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If the forward control gain is increased to handle wide input voltage range, then the adaptability is improved, but the susceptibility to load disturbances worsens

Engineering Contradiction:

Improveforward control gain rangeVSAvoidload disturbance susceptibility

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent segments the control range into two distinct modes: normal switching mode for lower input voltages and rate-limited switching mode for higher input voltages. This segmentation allows the system to use appropriate control strategies for different operating conditions, reducing susceptibility to load disturbances while maintaining the ability to handle wide voltage ranges.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the control parameter by introducing rate-limited switching that adjusts the switching frequency dynamically. When the input voltage is high, the rate-limited mode reduces the switching frequency to limit the forward control gain, thereby reducing susceptibility to load disturbances while still maintaining adaptability to the wide input voltage range.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12206330B2Rate limiting for buck converters

Publication Date: 2025.01.21 HAMILTON SUNDSTRAND CORP

AI summary

A method of DC-DC power conversion includes converting a DC link voltage to a DC output voltage for a load that is lower than the DC link voltage using a buck converter. The method includes controlling the buck converter in a normal switching mode in response to the DC link voltage being below a predetermined high threshold. The method also includes controlling the buck converter in a rate limited switching mode in response to the DC link voltage being at or above the predetermined high threshold.