Impedance Transformation Network for Wireless Power Efficiency
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Solution Overview
Problem
Wireless power transfer systems face inefficiencies when dealing with varying resistive and reactive impedances in load circuits, leading to fluctuations in power output and efficiency, particularly when charging multiple devices simultaneously.
Innovation Solution
A transmitter apparatus with a driver circuit and a filter circuit that includes a single shunt capacitor network, designed to maintain efficiency and power output within a complex impedance range by transforming variable impedances to optimal values, ensuring efficient power transfer across a wide range of resistive and reactive variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a driver circuit is used to power wireless charging without impedance transformation, then the circuit structure is simple, but the efficiency drops significantly when dealing with varying resistive and reactive impedances
Solution Approach 1:
An impedance transformation network is introduced as an intermediary component between the driver circuit and the wireless charging load. This network transforms varying complex impedances (resistive and reactive) into a standardized impedance, enabling the driver circuit to operate efficiently without directly encountering load variations. The intermediary network decouples the driver circuit from load impedance variations, resolving the contradiction between maintaining simple circuit structure and achieving efficient power transfer across varying impedances.
Solution Approach 2:
The impedance transformation network dynamically adjusts impedance parameters (resistance and reactance values) to match varying load conditions. By changing the transformation ratio based on load requirements, the system maintains optimal efficiency across different operating conditions while preserving a relatively simple overall circuit architecture. This parameter adaptation allows efficient power transfer without requiring complex control circuits.
2Loss of energy
If the impedance transformation network transforms all complex impedances to a single standardized value, then the driver circuit efficiency is maximized, but the adaptability to different power output requirements is reduced
Solution Approach 1:
The impedance transformation network employs dynamic transformation ratios that can be adjusted based on different operating conditions. Rather than using a fixed transformation ratio, the network adapts its transformation characteristics to match both efficiency requirements and power output demands. This dynamic capability allows the system to maintain high efficiency while simultaneously providing adaptability to different power output requirements by varying the transformation parameters in real-time.
Solution Approach 2:
The impedance transformation network is designed to perform multiple functions: it transforms impedances for efficiency optimization, regulates power output levels, and adapts to different load conditions. By integrating these multiple functions into a single network, the system achieves both maximized driver circuit efficiency and maintained adaptability to different power requirements, eliminating the need for separate control mechanisms.
3Loss of energy
If a filter circuit is added to maintain efficiency within 20% of maximum, then the efficiency is improved, but the device complexity increases
Solution Approach 1:
The filter circuit is merged with the impedance transformation network into a single integrated structure. By combining the filtering function with the impedance transformation function, the system achieves efficiency improvement without adding a separate, independent filter circuit. This integration reduces the overall component count and simplifies the circuit architecture while still maintaining the efficiency benefit of having a filter to suppress harmonics and improve power quality.
Solution Approach 2:
The combined filter-impedance transformation network performs multiple functions simultaneously: impedance transformation for efficiency optimization, filtering for harmonic suppression, and power regulation. This multi-functional design achieves efficiency improvement within 20% of maximum while avoiding the complexity increase that would result from adding separate dedicated circuits for each function.
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
The solution maintains efficiency within 20% of maximum efficiency and provides a substantially constant power output level, even with reactive variations, ensuring reliable and efficient wireless charging across diverse impedance ranges.
Implementation Method 1
A filter circuit electrically connected between the driver circuit and the transmit circuit and configured to transform variable complex impedance presented by the transmit circuit to values that maintain the efficiency of the driver circuit within 20% of a maximum efficiency of the driver circuit
Implementation Method 2
The filter circuit is further configured to maintain a substantially constant power output level irrespective of the reactive variations within the complex impedance range
Data Source
AI summary
This disclosure provides systems, methods and apparatus for reducing harmonic emissions. One aspect of the disclosure provides a transmitter apparatus. The transmitter apparatus includes a driver circuit characterized by an efficiency and a power output level. The driver circuit further includes a filter circuit electrically connected to the driver circuit and configured to modify the impedance of the transmit circuit to maintain the efficiency of the driver circuit at a level that is within 20% of a maximum efficiency of the driver circuit when the impedance is within the complex impedance range. The filter circuit is further configured to maintain a substantially constant power output level irrespective of the reactive variations within the complex impedance range. The filter circuit is further configured to maintain a substantially linear relationship between the power output level and the resistive variations within the impedance range.