Switching Converter Driver Control for Dynamic Dead Time

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Solution Overview

Problem

Existing DC-DC switching converters face inefficiencies due to fixed dead time between switching phases, leading to increased diode conduction losses and high power consumption, especially at high input voltages, and inefficient management of switch operations in source/sink modes.

Innovation Solution

A DC-DC switching converter with a driver stage and output current sensing circuit that dynamically adjusts the activation of power switches based on the sensed output current, using a capacitive level shifter for fast transitions and an anti-cross conduction mechanism to prevent cross-conduction losses, eliminating the need for fixed dead time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fixed dead time is defined between the on and off phases of the half bridge to avoid cross conduction, then cross conduction is prevented, but intrinsic diode conduction losses increase due to inefficient transition between switching phases

Engineering Contradiction:

Improvecross conduction preventionVSAvoidintrinsic diode conduction losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent implements dynamic dead time adjustment by sensing the output current and selectively delaying the activation of power switches based on the current direction. The control stage dynamically modifies the dead time parameter: applying it in source mode (positive current) to prevent diode conduction losses, and removing it in sink mode (negative current) to enable efficient transition, thus adapting the system behavior to real-time operating conditions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the dead time parameter from a fixed value to a variable that depends on the output current sign. The control stage selectively applies the dead time delay based on current direction sensing, transforming the static parameter into a dynamic one that optimizes performance across different operating modes (source/sink modes)

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If resistive or crossed level shifters are used for signal level shifting from low voltage domain to high voltage domain, then level shifting is achieved, but static and dynamic power consumption increases especially at high input voltages

Engineering Contradiction:

Improvesignal level shifting capabilityVSAvoidstatic and dynamic power consumption

Core Design Contradiction:

Ease of operationVSUse of energy by stationary object

Solution Approach 1:

The patent replaces resistive level shifters (passive mechanical/electrical components) with an active capacitive level shifter circuit. This substitution eliminates the continuous power consumption inherent in resistive dividers while maintaining the voltage level shifting function, significantly reducing both static and dynamic power consumption especially at high input voltages

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Loss of energy

If a minimum fixed time (watchdog time) is defined after switching phase change to avoid intrinsic diode conduction losses, then diode conduction losses are reduced, but switch activation efficiency decreases in source/sink mode operation

Engineering Contradiction:

Improveintrinsic diode conduction lossesVSAvoidswitch activation efficiency

Core Design Contradiction:

Loss of energyVSProductivity

Solution Approach 1:

The patent makes the watchdog time dynamic by selectively applying it based on output current direction. The control stage senses the current sign and applies the minimum fixed time delay only when appropriate (in source mode), while enabling immediate switch activation in sink mode, thus optimizing both energy loss prevention and activation efficiency across different operating conditions

Inventive Principle:

Principle #15Dynamics

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

This solution improves efficiency by reducing power losses and dynamic power consumption, allowing for optimized switch operation in both source and sink modes, enhancing overall converter performance.

Implementation Method 1

using a capacitive level shifter for fast transitions

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS11888397B2Driver circuit for switching converters

Publication Date: 2024.01.30 STMICROELECTRONICS SRL

AI summary

A DC-DC switching converter includes power switches selectively coupling an output terminal with a first voltage or with a second voltage. A driver stage is coupled with the power switches for driving the power switches. A driver control stage is coupled with the driver stage for controlling the operation of the driver stage. An output current sensing circuit is coupled with the output terminal and with the driver control stage, and is configured to sense a sign of an output current delivered by the DC-DC switching converter at the output terminal and to generate control signals for the driver control stage. The driver control stage controls the operation of the driver stage according to states of the control signals received from the output current sensing circuit, for selectively delaying the activation of the power switches depending on the sensed sign of the output current.