Class E Coil Array Amplifier With Load-Independent TX Current
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Solution Overview
Problem
Current wireless charging systems face challenges in achieving high efficiency and stability when charging multiple devices of different sizes and orientations due to sensitivity to output impedance and time-varying loads, limiting the design to single coil structures and restricting freedom in coil alignment.
Innovation Solution
A 3D coil array system with load-independent Class E power amplifiers and LCL-π matching networks, allowing multiple coils to be selectively activated with different phase and amplitude relationships, and using independent matching networks to maintain a constant transmitting coil current regardless of load variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single planar coil structure is used, then the device complexity is reduced, but the adaptability in coil alignment and positioning freedom is limited
Solution Approach 1:
The transmitter is divided into multiple independent coils arranged in a three-dimensional configuration rather than using a single planar coil. Each coil can be independently controlled and optimized for specific spatial positions, enabling flexible alignment with receivers at various orientations and locations while maintaining manageable complexity through modular design
Solution Approach 2:
The coil arrangement transitions from a two-dimensional planar structure to a three-dimensional spatial configuration. This dimensional expansion allows coils to be positioned at different heights and angles, providing freedom in alignment and accommodating receivers with various orientations without significantly increasing overall system complexity
2Loss of energy
If close alignment between transmitter and receiver is used, then power transfer efficiency is improved, but the adaptability to different device positions and orientations is reduced
Solution Approach 1:
The transmitter array segments power transfer into multiple independent coil channels, each capable of being individually optimized for its specific spatial relationship with the receiver. This allows the system to maintain high efficiency by selecting and optimizing specific coil pairs while accommodating various device positions and orientations
Solution Approach 2:
The system dynamically selects and activates specific coils within the array based on the real-time position and orientation of the receiver. This dynamic adaptation enables the system to maintain optimal coupling and power transfer efficiency regardless of how the receiver is positioned or oriented in space
3Reliability
If conventional power amplifiers are used, then the device complexity is reduced, but the system stability under time-varying loads and impedance variations deteriorates
Solution Approach 1:
The power amplifier incorporates feedback mechanisms that continuously monitor output current and impedance conditions, automatically adjusting operating parameters to maintain stable performance. This feedback control ensures consistent power transfer and protects against overheating and inefficiency under varying load conditions
Solution Approach 2:
The power amplifier dynamically changes operating parameters such as switching frequency, duty cycle, and impedance matching in response to detected load variations. These parameter adjustments allow the system to maintain optimal efficiency and stability across a wide range of operating conditions without requiring overly complex hardware
4Adaptability or versatility
If multiple coils are selectively activated, then the adaptability to different device configurations is improved, but the device complexity increases
Solution Approach 1:
The coil array is segmented into independently controllable units, each with its own control logic and switching circuitry. This segmentation allows the system to activate only the necessary subset of coils for any given receiver configuration, providing multi-device support while keeping control complexity manageable through modular architecture
Solution Approach 2:
The control system implements universal switching logic that can selectively activate any combination of coils based on receiver position and configuration. This multi-functional control approach allows a single system to handle various device types, positions, and orientations without requiring separate control circuits for each scenario
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 power transfer efficiency and system stability by maintaining constant TX coil current across a wide range of impedance variations, supporting multiple devices with improved freedom in positioning and orientation, and reducing power consumption and component overheating.
Implementation Method 1
control circuitry configured to adjust a magnetic field generated by the 3D coil array
Implementation Method 2
independent matching networks comprising a matching inductance in series with a corresponding TX coil and a matching capacitance in parallel with the corresponding TX coil
Data Source
AI summary
Various examples are provided for power amplifiers for coil array systems, which include load-independent Class E power amplifiers. In one example, a wireless charging system includes a three-dimensional (3D) coil array; and control circuitry configured to adjust a magnetic field generated by the 3D coil array, the control circuitry comprising a switching structure coupled to transmitting (TX) coils of the 3D coil array via independent matching networks. The independent matching networks can be LCL-matching networks.