Power Inverter Dead-Time Control via Reflected Impedance
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Solution Overview
Problem
DC-AC power converters face efficiency reduction due to high switching losses and varying load characteristics, which are exacerbated by fixed dead-time settings that do not account for changing load impedances.
Innovation Solution
A control circuit that dynamically adjusts the dead-time of switching stages and the capacitance of a tunable matching network based on reflected impedance, optimizing switching efficiency and reducing power losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dead-time is increased to allow switching voltages to stabilize, then switching reliability is improved, but power converter efficiency deteriorates
Solution Approach 1:
The patent implements dynamic dead-time adjustment by sensing the actual switching voltage stabilization time and adapting the dead-time duration accordingly. Instead of using a fixed conservative dead-time value, the system continuously monitors the switching process and adjusts the dead-time to match the actual requirements, thereby minimizing unnecessary dead-time losses while ensuring reliable switching operation.
Solution Approach 2:
The patent changes the dead-time parameter from a fixed value to a dynamically adjusted value based on real-time switching conditions. By monitoring voltage stabilization and adjusting the dead-time duration as a variable parameter, the system optimizes the trade-off between switching reliability and power converter efficiency under different operating conditions.
2Productivity
If switching frequency is increased to improve power converter output, then productivity is improved, but switching losses increase
Solution Approach 1:
The patent dynamically adjusts the dead-time parameter in response to varying switching frequencies and load conditions. By continuously adapting the dead-time to match actual switching requirements at different frequencies, the system minimizes switching losses while maintaining high productivity and power converter output.
3Loss of energy
If dead-time is reduced to improve efficiency, then power converter efficiency is improved, but switching voltage stability deteriorates
Solution Approach 1:
The patent employs feedback mechanisms by sensing the actual switching voltage stabilization time and using this information to adjust the dead-time duration. The system continuously monitors whether the reduced dead-time is sufficient for voltage stabilization and adapts accordingly, ensuring both efficiency and voltage stability are maintained.
Solution Approach 2:
The patent performs preliminary sensing of switching voltage conditions before finalizing the dead-time adjustment. By monitoring voltage stabilization in advance and predicting the required dead-time, the system prevents switching instability while maintaining high efficiency operation.
Data Source
AI summary
A wireless power transmitter includes circuitry configured to determine a reflected impedance from a receiver coil at a transmitter coil and control a dead-time of one or more switching stages of a power conversion device based on the reflected impedance. A tunable matching network at the transmitter is controlled based on the reflected impedance and the dead-time of the one or more switching stages.