Buck SMPS Transient Response via Hysteretic-PWM Hybrid Control

Solution Overview

Problem

Existing buck switch-mode power supply (SMPS) systems face challenges in optimizing their response to disturbances due to variable frequency and increased ripple in strictly hysteretic controlled systems, leading to reduced phase margin and stability concerns.

Innovation Solution

Combining hysteretic control with fixed frequency pulse-width modulation (PWM) control to enhance the SMPS system's response to disturbances, using a fast outer hysteretic control in conjunction with traditional peak current mode PWM control to manage deviations and maintain stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If strictly hysteretic control is used, then response to disturbance is optimized, but variable frequency and increased ripple occur leading to reduced phase margin and stability concerns

Engineering Contradiction:

Improveresponse to disturbanceVSAvoidphase margin and stability

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The control system is segmented into two distinct modes: hysteretic control mode for fast transient response and PWM control mode for stable steady-state operation. The controller selectively switches between these modes based on the operational conditions, allowing the system to benefit from the fast response of hysteretic control during transients while maintaining the stability of PWM control during normal operation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The control system dynamically adapts its behavior by switching between hysteretic and PWM control modes based on the magnitude of the disturbance and system state. This dynamic adaptation allows the system to optimize its response characteristics for different operating conditions, achieving fast transient response when needed while maintaining stability during steady-state operation.

Inventive Principle:

Principle #15Dynamics

2Speed

If dual edge modulation or increased bandwidth control techniques are used, then response to large disturbance is improved, but phase margin is reduced and stability concerns arise during normal operation

Engineering Contradiction:

Improveresponse to large disturbanceVSAvoidphase margin

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The control system is segmented into two distinct modes: hysteretic control mode for fast transient response and PWM control mode for stable steady-state operation. The controller selectively switches between these modes based on the operational conditions, allowing the system to benefit from the fast response of hysteretic control during transients while maintaining the stability of PWM control during normal operation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The control system changes its operating parameters by switching between hysteretic and PWM control modes. During large disturbances, the system adopts hysteretic control with its characteristic fast response parameters. During normal operation, it transitions to PWM control with its stable phase margin parameters, thus optimizing performance for each operational regime.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP2596573B1Buck switch-mode power converter large signal transient response optimizer

Publication Date: 2019.08.28 MICROCHIP TECHNOLOGY INC

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AI summary

A switch mode power supply (SMPS) response to a disturbance is improved by using a hysteretic control in combination with a fixed frequency, pulse-width modulated (PWM) controller for providing robust control and optimizing the response to disturbances in buck or buck derived switch mode power supply (SMPS) system topologies.