Half-Bridge Dead-Time Control Using Half-Bridge Voltage Feedback
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Solution Overview
Problem
Half-bridge power circuits face challenges in minimizing dead-time to prevent shoot-through while accommodating PVT variations, leading to inefficiencies and power losses.
Innovation Solution
A controller system with measurement and delay circuits that dynamically adjust the dead-time and slew rate of control signals for the high-side and low-side switches based on real-time half-bridge voltage measurements, ensuring optimal switching times and minimizing reverse recovery losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the dead-time is minimized to reduce power loss, then power efficiency is improved, but the risk of shoot-through increases due to PVT variations
Solution Approach 1:
The patent implements dynamic dead-time adjustment by measuring the actual turn-off time of the low-side switch and using this measurement to adaptively set the dead-time for the high-side switch. This dynamic approach allows the system to optimize the dead-time parameter in real-time based on actual device behavior, thereby reducing power loss while maintaining reliable shoot-through prevention despite PVT variations.
Solution Approach 2:
The system employs feedback mechanisms by measuring the half-bridge voltage to determine when the low-side switch has fully turned off, and using this feedback information to control the timing of the high-side switch activation. This closed-loop feedback ensures that the dead-time is precisely adjusted to match actual switch behavior, preventing shoot-through while minimizing unnecessary delay.
2Device complexity
If a fixed dead-time is used to simplify control, then device complexity is reduced, but performance optimization under PVT variations is limited
Solution Approach 1:
The system performs self-characterization by automatically measuring its own switch turn-off times and using these measurements to configure optimal dead-time values. This self-service approach eliminates the need for external characterization equipment or complex manual tuning, achieving adaptive performance optimization while keeping the control circuit relatively simple.
Solution Approach 2:
The patent changes the dead-time parameter dynamically based on measured switch behavior and operating conditions. By adjusting this critical timing parameter according to actual PVT variations, the system achieves optimal performance across different conditions without requiring a completely complex control architecture.
Data Source
AI summary
A controller for a half-bridge power circuit includes a measurement circuit, a controller circuit, a high-side delay circuit, and a low-side delay circuit. The measurement circuit connects to the half-bridge node, measures the half-bridge voltage, and generates a multi-bit status signal indicative of the measured half-bridge voltage. The controller circuit connects to the measurement circuit, and receives the status signal therefrom. The controller circuit generates at least a delay control signal based on the status signal. The high-side delay circuit connects to the controller circuit to receive the delay control signal. The high-side delay circuit provides a high-side control signal in response to the delay control signal, to switch on/off the high-side switch. The low-side delay circuit connects to the controller circuit to receive the delay control signal. The low-side delay circuit provides a low-side control signal in response to the delay control signal, to switch on/off the low-side switch.