Adaptive Dead Time Controller for Power Electronics Half-Bridges

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Solution Overview

Problem

Power electronics switches in vehicles experience high conductance losses due to inappropriate dead time, leading to short circuits and overheating, as existing solutions fail to optimize dead time effectively.

Innovation Solution

A controller determines an adaptive dead time based on commutation time and minimum values, using a microcontroller or FPGA to generate control signals for power semiconductor switches, ensuring the dead time is optimized to prevent crosscurrents and double switching, thereby reducing conductance losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a long dead time is used to prevent crosscurrents and short circuits, then reliability is improved, but conductance losses increase due to extended reverse conductance period

Engineering Contradiction:

Improveprevention of crosscurrents and short circuitsVSAvoidconductance losses in reverse conductance

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies dynamics by making the dead time adjustable and adaptive rather than fixed. The controller dynamically adapts the dead time duration based on operating conditions, switching between a first dead time (longer) for prevention and a second dead time (shorter) for efficiency, thereby resolving the contradiction between reliability and energy loss

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of dead time duration based on operating conditions. By switching between different dead time values (first and second dead times) depending on whether the power semiconductor is in reverse conductance mode or not, the system optimizes both reliability and energy efficiency

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If the dead time is optimized to reduce conductance losses, then energy efficiency is improved, but the risk of crosscurrents and short circuits increases

Engineering Contradiction:

Improveconductance lossesVSAvoidprotection against crosscurrents and short circuits

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent uses feedback by continuously monitoring the operating state of the power semiconductor (detecting reverse conductance conditions) and adjusting the dead time accordingly. The controller receives feedback about the switching state and adapts the dead time to maintain both efficiency and safety

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically switches between different dead time configurations based on real-time operating conditions, making the dead time adaptive rather than static, thereby resolving the contradiction between energy efficiency and reliability

Inventive Principle:

Principle #15Dynamics

3Reliability

If different switching speeds are compensated with fixed dead time, then operational safety is improved, but system adaptability decreases

Engineering Contradiction:

Improveoperational safety of inverted switchesVSAvoidadaptability to different operating conditions

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent makes the dead time dynamic and adaptive to different operating conditions rather than fixed. By adjusting the dead time based on whether the power semiconductor is in reverse conductance mode or not, the system maintains operational safety while adapting to varying conditions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the dead time parameter based on operating conditions, switching between a first dead time for safety-critical moments and a second dead time for normal operation, thereby maintaining both safety and adaptability

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11462993B2Controller for determining dead times for power electronics half-bridges

Publication Date: 2022.10.04 ZF FRIEDRICHSHAFEN AG

AI summary

A controller for controlling a bridge circuit in a vehicle power module, comprising an input interface for receiving an output current from the bridge circuit, an evaluation unit for determining an adaptive dead time based on the output current, wherein the adaptive dead time is coupled to a predetermined commutation time for the bridge circuit and limited by a predetermined minimum value, and a signal unit for generating a control signal for sending the adaptive dead time to the bridge circuit.