Variable Capacitance Resonant Converter for Wireless Power
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Solution Overview
Problem
Resonant power converters face challenges in maintaining high efficiency due to component tolerance issues, making it difficult to set the resonant frequency accurately, and existing systems require separate power stages for voltage and power regulation in wireless power transfer, leading to high costs and low efficiency.
Innovation Solution
The implementation of a resonant power conversion system with a variable capacitance network, including a voltage shifting diode and capacitor-switch branches, allows for magnetic coupling of coils and adjustment of capacitance to regulate output voltage, enabling efficient operation at or near resonant frequency without the need for separate power stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If resonant power converters operate at high switching frequency, then power loss of power switches is reduced, but it becomes difficult to maintain high efficiency operation due to component tolerance making resonant frequency control imprecise
Solution Approach 1:
The patent applies dynamics by making the capacitance value adjustable and variable in real-time. The resonant frequency is dynamically tuned by changing the capacitance of the resonant tank capacitor through switching between different capacitor values, allowing the system to adapt to component tolerances and maintain optimal resonant frequency despite variations in inductor and capacitor values.
Solution Approach 2:
The patent changes the parameter of capacitance to control resonant frequency. By switching between different capacitance values (e.g., first capacitance value and second capacitance value), the resonant frequency can be adjusted to compensate for component tolerances and maintain high efficiency operation at the desired switching frequency.
2Ease of operation
If a separate power stage is used to regulate power transfer in wireless power transfer systems, then voltage and power control is achieved, but system cost increases and efficiency decreases
Solution Approach 1:
The patent merges the power conversion function and voltage regulation function into a single resonant power conversion stage. The resonant tank with adjustable capacitance serves dual purposes: performing power conversion and regulating output voltage by controlling the resonant frequency, thereby eliminating the need for a separate power stage and reducing system complexity.
Solution Approach 2:
The resonant power conversion stage is designed to perform multiple functions simultaneously. It provides both power conversion and voltage regulation capabilities through the adjustable capacitance mechanism, making the system more versatile while reducing the number of required components.
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 approach enhances the efficiency and cost-effectiveness of resonant power conversion by allowing precise control of output voltage and power transfer, reducing component costs and improving system performance in wireless power transfer applications.
Implementation Method 1
magnetically coupling a first coil of a wireless power transfer system to a second coil of the wireless power transfer system
Implementation Method 2
resonant power converters were developed to improve the efficiency of the power conversion. However, a resonant power converter can achieve the best efficiency only when it operates at or close to a resonant frequency
Data Source
AI summary
A method includes magnetically coupling a first coil of a wireless power transfer system to a second coil of the wireless power transfer system, wherein the first coil is coupled to a first resonant tank comprising a first variable capacitance network, and the second coil is coupled a second resonant tank comprising a second variable capacitance network, and adjusting a capacitance of at least one of the first variable capacitance network and the second variable capacitance network to regulate an output voltage of the wireless power transfer system.