Wireless Power Rectifier Timing Using Zero-Crossing Detection
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Solution Overview
Problem
Wireless power systems face inefficiencies in active rectification due to challenges in controlling switches to manage oscillating currents effectively, leading to suboptimal power transmission and potential hardware size, weight, and cost increases.
Innovation Solution
The implementation of an active rectification method that uses zero-crossing detectors to determine delay times based on wireless power system parameters, generating control signals for switches in a rectifier to insert dead times, thereby optimizing switch operation and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If active rectification is used in wireless power systems, then power transmission efficiency is improved, but control complexity of switches increases
Solution Approach 1:
The patent changes the control parameters by introducing delay time based on zero-crossing detection and inserting dead time between control signals. This transforms the switching control from direct synchronization to a delayed, dead-time-compensated approach, optimizing the rectification process while managing control complexity through parameter adjustment rather than structural complexity
Solution Approach 2:
The patent implements feedback by detecting zero-crossings of the oscillating current and using this information to determine appropriate delay times for switch control. This feedback mechanism allows the system to adapt the switching timing to the actual current state, improving efficiency while keeping the control logic systematic and manageable
2Loss of energy
If tunable impedance matching components are added to optimize power transmission, then power transmission efficiency is improved, but system size and weight increase
Solution Approach 1:
The patent extracts or removes the need for tunable impedance matching components by implementing active rectification with zero-crossing detection and dead time insertion. The efficiency improvement is achieved through control methodology rather than additional hardware, thereby avoiding the weight penalty that would accompany traditional impedance matching solutions
3Loss of energy
If dead time is inserted between control signals, then switch operation efficiency is improved, but power transmission time is increased
Solution Approach 1:
The patent optimizes the dead time parameter by determining it based on zero-crossing detection and wireless power system parameters. Rather than using a fixed or excessive dead time, the system calculates the minimum necessary dead time to ensure proper switch operation, thereby minimizing the time loss while still achieving the efficiency benefits of controlled switching
Data Source
AI summary
Described herein are active rectification methods and systems for a rectifier of a wireless power system. Exemplary methods can include detecting, by a zero-crossing detector, one or more zero-crossings of a current at an input of the rectifier and determining a first delay time based on at least one wireless power system parameter and the zero-crossings. The methods can include generating first and second control signals for first and second switches of the rectifier, respectively, based on the first delay time; inserting a first dead time between the first control signal and the second control signal; and providing the first and second control signals to the first and second switches, respectively.