Class-E Oscillator Switching Control for Wireless Power Efficiency
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Solution Overview
Problem
Wireless power transmission systems using resonant magnetic coupling face efficiency drops due to impedance mismatch caused by changes in the environment around the antennas, such as variations in the antenna gap or the presence of metal or magnetic materials.
Innovation Solution
A wireless power transmission system that includes a class-E oscillator circuit with a switching element and capacitor, and a switching control section that adjusts the switching element's conduction state based on a control signal, switching from non-conductive to conductive when a preset time period has elapsed or when a potential difference across the element reaches a local minimum, to maintain efficient power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If preset circuit constants are used in the transmitting-side and receiving-side circuit blocks, then high transmission efficiency is achieved under design conditions, but transmission efficiency decreases when environmental conditions change causing impedance mismatch
Solution Approach 1:
The patent applies dynamics by making the circuit constants adjustable rather than fixed. The transmitting-side and receiving-side circuit blocks can dynamically change their circuit constants (inductance and capacitance values) in response to environmental changes, allowing the system to adapt to varying impedance conditions and maintain high transmission efficiency across different operating scenarios
Solution Approach 2:
The patent implements parameter changes by modifying the circuit constants (inductance L and capacitance C) of the resonant circuits based on detected impedance conditions. When environmental changes cause impedance mismatch, the system adjusts these parameters to restore optimal coupling and maintain efficient power transmission
2Adaptability or versatility
If the gap between transmitting and receiving antennas changes or foreign materials enter the transmission path, then the impedance of resonators changes, but this causes impedance mismatch and decreased transmission efficiency
Solution Approach 1:
The patent employs feedback by detecting the impedance conditions of the resonators and using this information to adjust the circuit constants. The system continuously monitors the transmission path conditions and dynamically modifies the inductance and capacitance values to compensate for gap changes or foreign material interference, thereby maintaining optimal power transfer efficiency
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 effectively suppresses the decrease in transmission efficiency caused by impedance mismatch, ensuring stable power delivery even with changing environmental conditions or varying load impedance.
Implementation Method 1
a resonant magnetic coupling method... two resonators (antennas) are magnetically coupled together via the evanescent tail of oscillation energy generated in space in the vicinity of the resonators
Implementation Method 2
two resonators (antennas) are magnetically coupled together via the evanescent tail of oscillation energy generated in space in the vicinity of the resonators, to thereby wirelessly transmit the oscillation energy
Implementation Method 3
a switching element and a capacitor which are connected in parallel to the DC energy source, for converting the DC energy into the AC energy
Data Source
AI summary
A wireless power transmission system includes: a power transmitting section that converts DC energy input from a DC energy source into AC energy of a frequency f0; a transmitting antenna; and a receiving antenna. The power transmitting section includes: a class-E oscillator circuit including a switching element and a capacitor which are connected in parallel to the DC energy source, for converting the DC energy into the AC energy; and a switching control section that inputs a control signal for controlling a conduction state of the switching element to the switching element. The switching control section switches the switching element from a non-conductive state to a conductive state when a preset time period has elapsed or when a potential difference across the switching element takes a local minimum value after the switching element is switched from the conductive state to the non-conductive state.