Wireless Power Transfer Voltage Regulation via Hysteretic Impedance Control
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Solution Overview
Problem
Existing wireless power transfer (WPT) systems face inefficiencies at light-load conditions due to unregulated transmitters and complex, costly designs that require additional components and sensing coils, leading to bandwidth limitations and reduced dynamic performance.
Innovation Solution
Implementing a wireless hysteretic control system that achieves both transmitter power regulation and receiver voltage regulation without off-chip components or coils, using a monolithic chip design with integrated current sensors to maintain stability and efficiency across varying load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If linear analog control methodologies are used for TX regulation, then voltage regulation is achieved, but system complexity increases due to extra discrete components
Solution Approach 1:
The patent combines the TX regulation functionality with the existing LSK backscattering communication channel by modulating the TX coil impedance through the same resonant circuit, eliminating the need for separate discrete components and sensing coils. The impedance modulation is achieved by switching capacitors in parallel with the TX coil, integrating control functions into the existing power transfer circuitry.
Solution Approach 2:
The TX coil and resonant circuit serve multiple functions: power transfer, communication (LSK backscattering), and regulation (via impedance modulation). By making the TX circuit multi-functional, the patent eliminates dedicated regulation components while maintaining all necessary functions through a unified circuit architecture.
2Reliability
If linear analog control methodologies are used for TX regulation, then voltage regulation is achieved, but bandwidth is limited and dynamic performance is reduced
Solution Approach 1:
The patent transitions from static linear analog control to dynamic switching control. The TX circuit uses switching capacitors that can be rapidly switched between states to modulate impedance, enabling high-bandwidth operation and fast transient response. This dynamic switching approach eliminates the bandwidth limitations inherent in linear analog control while maintaining regulation capability.
3Reliability
If extra sensing coils are added to extract LSK signals, then TX regulation is achieved, but TX coil area increases significantly
Solution Approach 1:
The patent extracts the LSK signal detection function from a separate sensing coil and integrates it into the existing TX coil circuitry. By detecting impedance changes directly through the TX coil's resonant circuit, the system eliminates the need for additional sensing coils while maintaining the ability to extract LSK signals for regulation control.
4Device complexity
If unregulated transmitter is used, then system complexity is reduced, but end-to-end efficiency degrades at light-load conditions
Solution Approach 1:
The patent changes the operating parameters of the TX circuit by dynamically modulating the resonant frequency and impedance through capacitor switching. This enables the TX to adapt its operating point to match load conditions, maintaining high efficiency at light loads by adjusting the resonant circuit parameters rather than operating at fixed capacity.
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 enables instant load-transient response and enhanced end-to-end light-load efficiency, reducing system complexity and cost while maintaining stability and efficiency, with up to 37% end-to-end efficiency enhancement compared to previous designs.
Implementation Method 1
power is received wirelessly from a transmitter
Implementation Method 2
A current sensor of the transmitter senses the changes in current in the driver, and the changes in current are responsive to the receiver adjusting an amount of power wirelessly received
Data Source
AI summary
A variety of applications can include wireless power and voltage regulation for wireless power transfer systems. A receiver can receive power wirelessly from a transmitter to provide an output voltage. The receiver can regulate the output voltage with respect to a window defining an upper threshold and a lower threshold and can generate a first signal in response to the output voltage exceeding the upper threshold voltage and a second signal in response to the output voltage reducing below the lower threshold voltage. The receiver can change its input impedance and control reception of the power in response to the first and second signals. A transmitter can sense current in the power transistors or the coil of the transmitter in response to the change of input impedance of the receiver. The sensed current can be used to modify the current to the output of the transmitter to adjust the transmitted power.