Digital Synchronous Converter Dead-Time Optimization

Solution Overview

Problem

Conventional digital synchronous switching converters face efficiency degradation due to suboptimal dead-time settings, leading to power losses from either prolonged body diode conduction or short switch conduction, and risk shoot-through when delay times are too short.

Innovation Solution

A control circuit with a driver that generates driving signals for power switches, a feedback loop to detect output voltage and generate digital feedback signals, a digital pulse width modulator to regulate output voltage, and a dead-time optimizer dynamically adjusts switch dead-time based on feedback signals to prevent simultaneous switch-on and optimize efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If dead-time is increased to prevent simultaneous switch-on, then shoot-through is prevented, but power loss increases due to prolonged body diode conduction

Engineering Contradiction:

Improveshoot-through preventionVSAvoidpower loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The dead-time is made dynamic rather than fixed. The control circuit continuously monitors the actual switching states of the power switches and dynamically adjusts the dead-time duration based on real-time conditions. This allows the system to use minimal dead-time when switches are turning off cleanly, and increase dead-time only when needed to prevent shoot-through, thereby reducing overall power loss while maintaining reliability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system implements feedback control by monitoring the actual switching states and using this information to adjust the dead-time. The control circuit detects whether body diodes are conducting or if switches are turning off properly, and uses this feedback to optimize the dead-time duration, preventing both shoot-through and excessive power loss.

Inventive Principle:

Principle #23Feedback

2Loss of energy

If dead-time is decreased to reduce power loss, then efficiency is improved, but shoot-through risk increases due to simultaneous switch-on

Engineering Contradiction:

Improvepower lossVSAvoidshoot-through prevention

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The dead-time is made dynamic rather than fixed. The control circuit continuously monitors the actual switching states of the power switches and dynamically adjusts the dead-time duration based on real-time conditions. This allows the system to use minimal dead-time when switches are turning off cleanly, and increase dead-time only when needed to prevent shoot-through, thereby reducing overall power loss while maintaining reliability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system implements feedback control by monitoring the actual switching states and using this information to adjust the dead-time. The control circuit detects whether body diodes are conducting or if switches are turning off properly, and uses this feedback to optimize the dead-time duration, preventing both shoot-through and excessive power loss.

Inventive Principle:

Principle #23Feedback

3Device complexity

If fixed delay times are imposed in conventional PWM optimization, then dead-time is controlled, but efficiency degradation occurs due to suboptimal settings

Engineering Contradiction:

Improvedead-time controlVSAvoidefficiency

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The dead-time is made dynamic rather than fixed. The control circuit continuously monitors the actual switching states of the power switches and dynamically adjusts the dead-time duration based on real-time conditions. This allows the system to use minimal dead-time when switches are turning off cleanly, and increase dead-time only when needed to prevent shoot-through, thereby reducing overall power loss while maintaining reliability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system implements feedback control by monitoring the actual switching states and using this information to adjust the dead-time. The control circuit detects whether body diodes are conducting or if switches are turning off properly, and uses this feedback to optimize the dead-time duration, preventing both shoot-through and excessive power loss.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8436594B2Control circuit and method for a digital synchronous switching converter

Publication Date: 2013.05.07 RICHTEK TECH

AI summary

In addition to an output voltage control loop, a dead-time optimization loop is provided for a digital synchronous switching converter to dynamically adjust the dead-time for the power switches of the converter. It is extracted a minimal feedback signal at a steady state while the output voltage remains under a specification, and a maximal efficiency of the digital synchronous switching converter is thus obtained.