Opportunity
Wireless Power Transmission (WPT) systems, utilizing magnetic resonant coupling, offer a promising solution for contactless charging in various applications such as consumer electronics, electric vehicles, and maritime transport due to their high reliability, safety, and user-friendliness. However, a critical challenge hindering optimal performance is the efficient estimation of the coupling coefficient between the transmitter and receiver coils. This coefficient is essential for achieving maximum power transfer efficiency through techniques like maximum efficiency tracking. Existing methods for estimating the coupling coefficient often rely on real-time system measurements that require wireless communication between the transmitter and receiver, introducing significant complexity, increased cost, and latency. Alternative approaches that avoid wireless communication have been proposed, such as using auxiliary inverters on the transmitter side or employing pulse density modulation with inter-harmonic analysis. Nevertheless, these methods still necessitate additional sensors, dedicated circuits, or complex computational algorithms, which raise system costs and design intricacy. Therefore, there is a pressing need for a low-cost, rapid, and hardware-efficient method to estimate the coupling coefficient in WPT systems without compromising accuracy or requiring extensive modifications to existing system architectures.
Technology
This patent presents an innovative method and corresponding device for estimating the coupling coefficient in a Wireless Power Transmission (WPT) system without requiring wireless communication, extra sensors, or complex hardware additions. The core innovation leverages the established linear relationship between the system's coupling coefficient (k) and the natural frequency (ω_n) of the current amplitude in the system's dynamic model. The technology involves intentionally introducing a small current perturbation, such as a single pulse, into the system's DC side, either at the transmitter's converter input or observable at the receiver's rectifier output. Following this perturbation, the resulting damped oscillatory response of the DC-side current is analyzed. The damping frequency (ω_d) of this oscillation, which approximates the system's natural frequency (ω_n ≈ ω_d) under conditions of low damping typical in WPT systems, is extracted. The coupling coefficient is then calculated directly using a derived formula: k = √2 (ω_n / ω_r), where ω_r is the system's known resonant frequency. This estimation can be performed independently on either the transmitter side (by analyzing the input current to the converter after applying a perturbation) or the receiver side (by analyzing the output current of the rectifier after the transmitter initiates a perturbation). The method is model-based, utilizing the system's inherent dynamic response, making it independent of output load voltage variations and eliminating the need for communication links or sophisticated signal processing.
Advantages
- Enables low-cost coupling coefficient estimation by eliminating the need for wireless communication modules (e.g., Bluetooth, Wi-Fi) between transmitter and receiver.
- Requires no additional sensors, auxiliary circuits (like extra inverters), or complex hardware components, simplifying system design and reducing bill-of-materials cost.
- Provides rapid estimation, typically achievable within a few switching cycles (e.g., ~1ms), with minimal disruption to steady-state system operation.
- Offers high estimation accuracy, with demonstrated errors often below 1% in validation tests.
- Exhibits strong robustness against variations in system parameters such as output voltage load, parasitic resistances, and minor detuning factors.
- Allows for independent estimation on either the transmitter or receiver side, providing implementation flexibility.
- Avoids complex computational algorithms, relying instead on a straightforward frequency measurement and a simple linear formula.
Applications
- Consumer electronics wireless charging pads and stands for smartphones, tablets, and wearables.
- Electric Vehicle (EV) wireless charging systems, both static and dynamic (in-motion).
- Wireless power systems for medical implants and portable medical devices.
- Industrial automation and logistics, such as powering automated guided vehicles (AGVs) and robots.
- Maritime and transportation systems for charging electric boats or aircraft.
- Internet of Things (IoT) devices and sensors requiring periodic or continuous wireless power.
- Smart home appliances and furniture with integrated wireless charging capabilities.
