Single-Stage Wireless Power Transfer Circuit with Zero Voltage Switching
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Solution Overview
Problem
Current wireless power transfer technologies using antenna-based near-field resonators are complex, costly, and inefficient due to the need for two-stage power converters and limited operating ranges of antenna coils.
Innovation Solution
A single-stage wireless power transmission circuit utilizing solid-state switches and a resonant circuit, where the controller operates the switches for zero voltage switching (ZVS) at a higher frequency than the resonant frequency, reducing switching losses and eliminating the need for an intermediate low voltage DC bus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a two-stage power converter is used to drive the antenna, then the antenna can be driven at the required voltage level, but the system complexity and cost increase
Solution Approach 1:
The patent combines the rectification and inversion functions into a single integrated power conversion stage. The antenna is directly coupled to the switching nodes of the power converter, eliminating the need for a separate intermediate voltage conversion stage. This merging of functions reduces system complexity while maintaining the required antenna drive capability.
2Power
If a two-stage power converter is used, then power conversion can be achieved, but efficiency decreases due to additional conversion stages
Solution Approach 1:
By merging the rectification and inversion operations into a single power conversion stage, the patent eliminates energy losses associated with intermediate voltage conversion. The direct coupling of the antenna to the switching nodes allows for efficient power transfer without the need for additional conversion stages.
3Ease of manufacture
If hard switching is used in the power converter, then the circuit is simpler to implement, but switching losses and EMI increase
Solution Approach 1:
The patent employs periodic resonant oscillations at the antenna operating frequency to naturally create zero-voltage switching conditions. The resonant circuit causes the voltage across the switches to periodically reach zero, allowing for lossless switching without complex control circuitry. This periodic resonant action achieves soft switching while maintaining implementation simplicity.
4Ease of manufacture
If the antenna operates at a fixed narrow voltage range, then the coil design is simplified, but the operating range and power transfer distance are limited
Solution Approach 1:
The patent makes the power converter operating frequency dynamic by coupling it to the resonant frequency of the antenna system. The converter operates at the resonant frequency, which can vary with load conditions and coupling strength. This dynamic frequency adjustment allows the system to adapt to different operating conditions and power transfer distances while maintaining efficient power transfer.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances efficiency, reduces complexity and cost, and allows for longer power transfer distances by enabling ZVS, which minimizes switching losses and electromagnetic interference (EMI) while maintaining high power transfer efficiency.
Implementation Method 1
A resonant circuit is coupled to the switch node and configured to resonate at a second frequency that is lower than the first frequency. The first frequency interacts with the resonant circuit creating out of phase voltage and current signals at the switch node.
Implementation Method 2
The out of phase signals enable the first and the second solid-state switches to operate with zero voltage switching
Implementation Method 3
An antenna network is coupled to the switch node and configured to transmit electrical energy at a first frequency
Data Source
AI summary
A control scheme and architecture for a wireless electrical energy transmission circuit employs two solid-state switches and a zero voltage switching (ZVS) topology to power an antenna network. The switches drive the antenna network at its resonant frequency and simultaneously energize a separate resonant circuit that has a resonant frequency lower than the antenna circuit. The resonant circuit creates out of phase voltage and current waveforms that enable the switches to operate with (ZVS).