Adaptive Dead Time Control for DC-DC Converter Efficiency

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Solution Overview

Problem

Existing DC-DC switching power converters face inefficiencies due to shoot-through current and variability in dead time caused by delay mismatches and ambient conditions, leading to inefficiencies and potential short circuits.

Innovation Solution

An adaptive dead time minimization scheme using a shoot-through detector and programmable delay cell to ensure non-overlapping operation of high and low side switches, with a fast response and tolerance to process and temperature variations, employing a bipolar device to sense edge transitions and adjust switching delays.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If dead time is increased to prevent short circuits, then reliability improves, but efficiency deteriorates due to energy loss during dead time

Engineering Contradiction:

Improveshort circuit preventionVSAvoidefficiency loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent implements dynamic adjustment of dead time based on real-time detection of body diode conduction events. The system continuously monitors the output node and adapts the non-overlapping time between high-side and low-side switches according to actual operating conditions, transitioning from static to dynamic control to optimize both reliability and efficiency

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent employs feedback mechanisms by detecting body diode conduction events at the output node and using this information to adjust the dead time setting. The detection circuit provides real-time feedback about switching conditions, enabling the control logic to modify the non-overlapping time to prevent short circuits while minimizing efficiency loss

Inventive Principle:

Principle #23Feedback

2Device complexity

If fixed dead time is used to simplify control, then device complexity reduces, but adaptability to process and temperature variations deteriorates

Engineering Contradiction:

Improvecontrol simplicityVSAvoidtolerance to variability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent implements self-service by enabling the system to automatically detect and adapt to its own operating conditions. The detection circuit monitors body diode conduction events and the control logic autonomously adjusts the dead time setting based on detected conditions, eliminating the need for external calibration or complex manual tuning across process and temperature variations

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent changes the dead time parameter dynamically based on detected body diode conduction events. The system adjusts the non-overlapping time between switches according to actual operating conditions, allowing the parameter to adapt to process and temperature variations while maintaining simple control architecture

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If operational transconductance amplifier based comparator is used to detect body diode conduction, then detection capability improves, but response speed deteriorates due to significant delay

Engineering Contradiction:

Improvebody diode conduction detectionVSAvoidresponse speed

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The patent extracts the essential detection function from complex operational transconductance amplifier based comparators and implements it through simpler circuitry that directly monitors the output node for body diode conduction events. This extraction removes unnecessary complexity and delay while preserving the core detection capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical/electronic complexity of operational transconductance amplifier based comparators with a simpler detection mechanism that directly senses body diode conduction at the output node. This substitution eliminates significant delay associated with complex comparator circuits, logic cells, and drivers while maintaining detection precision

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

The solution effectively minimizes dead time, preventing short circuits and efficiency losses, while maintaining adaptability to varying conditions, thus enhancing the efficiency of DC-DC switching converters and Class-D amplifiers.

Implementation Method 1

a bipolar device, configured to sense a rising or falling edge of the common output

Methodology Applied

Scientific EffectEdge detection:

Data Source

PatentUS10164531B2Adaptive control method for generating non overlapping time in output devices

Publication Date: 2018.12.25 DIALOG SEMICONDUCTOR (UK) LTD

AI summary

The disclosure describes an adaptive technique for generating minimum dead time in a DC-DC switching power converter, while ensuring no short circuit losses occur, resulting in efficiency improvement of the switching converter. In addition, this adaptive scheme makes sure that even the ambient conditions of the switching converter give the best decision at the ON/OFF timings of the switches. Body diode conduction feedback is detected, with reduced process sensitivity, and an algorithm is disclosed that finds the minimum dead time for a given load current, temperature, and process conditions.