Single-Inductor Dual-Output Converter Adaptive Control

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Solution Overview

Problem

Existing single-inductor multiple-output (SIMO) switching converters face challenges with large current ripples, inefficiency under light loads, and severe cross regulation issues, particularly in Continuous Conduction Mode (CCM), which limit load currents and increase power loss.

Innovation Solution

The proposed solution involves an adaptive common-mode control method and the addition of a fly capacitor across two outputs in a single-inductor dual-output (SIDO) buck converter, using PWM generators for control signals and weighting feedback output signals based on load currents to manage energy distribution and reduce ripples and cross regulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If time-multiplexing control is used in SIMO converters, then multiple outputs are achieved, but large current ripples and energy dissipation occur

Engineering Contradiction:

Improvemultiple output capabilityVSAvoidenergy dissipation during freewheeling

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The control is segmented into common-mode control for total energy management and differential-mode control for energy distribution between outputs. This segmentation allows independent optimization of each control function, reducing energy loss while maintaining multiple output capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements feedback mechanisms where the common-mode controller receives feedback from both outputs to regulate total energy, and the differential-mode controller receives feedback to distribute energy. This feedback system enables precise control that reduces energy dissipation during freewheeling states.

Inventive Principle:

Principle #23Feedback

2Device complexity

If ordered power-distributive control with comparators is employed, then control loop is simplified, but larger ripples and limited load current capability result

Engineering Contradiction:

Improvecontrol loop complexityVSAvoidoutput ripples

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent replaces simple comparator-based mechanical switching with PWM-based electronic control. The PWM generators produce controlled switching signals that reduce output ripples while maintaining simplified control loop architecture, overcoming the limitations of pure comparator-based systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If multiple PWM controllers driven by linear combinations of output errors are used, then large load currents are sustained, but large ripples and serious cross regulation problems occur

Engineering Contradiction:

Improveload current capabilityVSAvoidcross regulation

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The control is segmented into common-mode control for total energy management and differential-mode control for energy distribution. This segmentation decouples the control functions, allowing large load currents to be sustained while reducing cross-regulation effects between outputs.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The common-mode controller acts as an intermediary that manages total energy flow to both outputs, while the differential-mode controller mediates the distribution of energy between outputs. This intermediary control structure reduces direct interaction between outputs, minimizing cross-regulation problems.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Adaptability or versatility

If Discontinuous Conduction Mode (DCM) control is used, then multiple outputs are achieved, but load currents are limited

Engineering Contradiction:

Improvemultiple output capabilityVSAvoidload current limit

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent implements dynamic control that can adapt between continuous and discontinuous conduction modes. The common-mode and differential-mode controllers work together to maintain stable operation across different load conditions, enabling multiple outputs while supporting larger load currents than fixed DCM systems.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS8975879B2Switching converter having a plurality N of outputs providing N output signals and at least one inductor and method for controlling such a switching converter

Publication Date: 2015.03.10 DIALOG SEMICON GMBH

AI summary

This invention provides a switching converter having a plurality N of outputs providing N output signals and at least one inductor, comprising a first controlling device for controlling the total energy flowing over the inductor to the N outputs dependent on a first control signal, at least a second controlling device for distributing the total energy between the N outputs by means of at least a second control signal, wherein the first controlling device is coupled to all N outputs for receiving a number M of the respective feedback output signals of the N outputs, M≦N, wherein the first controlling device comprises first means for weighting the M feedback output signals and second means for providing the first control signal dependent on the weighted M feedback output signals.