Analog Predictive Dead-Time Control for Half-Bridge Switching
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Solution Overview
Problem
Existing Switching-Mode Power Supply (SMPS) systems face inefficiencies due to non-zero dead-time when switching between high-side and low-side switches in a half-bridge configuration, leading to power loss and potential cross-conduction issues, which are not adequately addressed by constant, adaptive, or digital predictive delay methods.
Innovation Solution
An analog-based approach that generates a phase difference voltage using control node voltages of switching elements, integrated through an analog Phase-Locked Loop (PLL), allowing for synchronization and zero dead-time switching by controlling a voltage-controlled delay module to ensure only one switch is active at a time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-zero dead-time is used when switching between high-side and low-side switches, then cross-conduction is avoided, but power loss increases and efficiency decreases
Solution Approach 1:
The patent implements dynamic dead-time adjustment by using a voltage-controlled delay module that adapts the dead-time duration based on real-time voltage conditions at the switching node. Instead of using a fixed dead-time value, the system dynamically modifies the delay period to match actual operating conditions, thereby minimizing unnecessary power loss while ensuring cross-conduction prevention is maintained when needed.
Solution Approach 2:
The system changes the dead-time parameter dynamically by controlling the voltage applied to the delay module. The control circuit adjusts the dead-time duration as a variable parameter rather than a constant, allowing optimization of power loss while maintaining reliability. This is achieved through voltage-controlled delay elements that respond to switching node conditions.
2Reliability
If a constant dead-time is used, then cross-conduction is avoided, but switching efficiency is reduced due to unnecessary delay
Solution Approach 1:
The patent transitions from static constant dead-time to dynamic adaptive dead-time control. The system continuously monitors switching node voltage and adjusts the dead-time duration in real-time, making the delay period a dynamic variable rather than a fixed constant. This enables the system to maintain reliability while optimizing switching efficiency under different operating conditions.
Solution Approach 2:
The control circuit automatically adjusts dead-time based on feedback from the switching node voltage without external intervention. The system self-regulates the delay period according to actual switching conditions, eliminating the need for manual tuning or fixed conservative dead-time values, thereby improving overall switching efficiency while maintaining safety.
3Loss of time
If digital predictive delay methods are used, then dead-time can be reduced, but system complexity increases
Solution Approach 1:
The patent replaces complex digital predictive delay circuits with an analog voltage-controlled delay implementation. Instead of using digital processors, counters, or complex logic circuits to predict and manage dead-time, the system uses analog voltage control mechanisms that respond directly to switching node conditions. This substitution significantly reduces system complexity while achieving comparable or superior dead-time reduction performance.
Solution Approach 2:
The patent introduces a voltage-controlled delay module as an intermediary between the PWM controller and the power switches. This intermediate analog component simplifies the control architecture by handling dead-time management through voltage-based delay rather than requiring complex digital prediction algorithms, thereby reducing overall system complexity while maintaining effective dead-time control.
Data Source
AI summary
A controller circuit for controlling switching elements and controlling dead-time of the switching elements is configured to generate a phase difference voltage using voltage at a control node of a first switching element and voltage at a control node of a second switching element. The first switching element is configured to couple a first node of a supply and a switch node and the second switching element is configured to couple the switch node and a second node of the supply. The controller circuit is further configured to generate a first driving signal based on a first pulse width modulation (PWM) signal for the first switching element and the phase difference voltage. The first driving signal includes a voltage-controlled delay module. The controller circuit is further configured to generate a second driving signal for driving the second switching element based a second PWM signal for the second switching element.