Opportunity
Wireless power transfer (WPT) systems, which operate via electromagnetic induction between a transmitter and a receiver, offer advantages such as simplicity, high efficiency, compactness, and low cost. However, a significant challenge in these systems is the physical isolation between the transmitting and receiving sides. Traditionally, critical operational parameters like the load voltage on the receiver side must be communicated back to the transmitter side using additional modules like Wi-Fi. This requirement increases system complexity, cost, and potential points of failure, as communication modules can be susceptible to environmental interference, leading to system instability. Furthermore, the mutual inductance between the transmitter and receiver coils is not static; it varies with changes in coil alignment or distance. This variation directly impacts power transfer efficiency. Without a precise, real-time method to identify this changing mutual inductance, it is impossible to dynamically optimize the system's operating parameters (e.g., frequency, phase) to maintain peak efficiency. Therefore, there is a pressing need for a method to eliminate the dependency on external communication modules for parameter feedback and to enable accurate, real-time identification of both mutual inductance and load voltage directly from the transmitter side to enhance system robustness and optimize efficiency.
Technology
This patent introduces a novel circuit and method for identifying both the mutual inductance (M) and the load voltage (V_o) in a WPT system without requiring any communication link between the receiver and transmitter. The core innovation involves inserting an equivalent inductor (L_S) in series at the output of the system's inverter on the transmitter side. The technology leverages the principle that voltage transients (sudden changes) generated by both the inverter on the transmitter side and the rectifier on the receiver side propagate through the magnetically coupled system. These transients induce corresponding voltage spikes across the added equivalent inductor. A mutual inductance and load voltage calculation module is employed to measure two specific voltage transient amplitudes across this inductor: the first amplitude (ΔV_LS1) caused by the inverter's switching transient and the second amplitude (ΔV_LS2) caused by the rectifier's switching transient. Using derived mathematical relationships, the system calculates the mutual inductance M from the first measured amplitude. Subsequently, using the identified M and the second measured amplitude, it calculates the load voltage V_o. The circuit may include components like a notch filter to suppress the fundamental operating frequency component, making the transients easier to detect, and a damping resistor to prevent oscillation. This method provides a fast response, is unaffected by system detuning or the presence of series compensation capacitors, and enables real-time optimization of the WPT system for maximum efficiency.
Advantages
- Eliminates the need for wireless communication modules (e.g., Wi-Fi, Bluetooth) between transmitter and receiver, reducing system cost, complexity, and potential failure points.
- Enables real-time, precise identification of mutual inductance, which is crucial for optimizing system efficiency, especially under dynamic conditions like coil misalignment.
- Provides simultaneous and accurate identification of the load voltage on the receiver side directly from the transmitter side measurements.
- Offers a fast response characteristic suitable for dynamic WPT applications.
- The identification method is robust and works accurately regardless of the system's detuning condition or the presence of series compensation capacitors.
- Simplifies system architecture and improves reliability by removing dependency on external communication.
Applications
- Dynamic wireless charging systems for electric vehicles (EVs), where coil alignment and distance vary.
- Consumer electronics wireless charging pads for smartphones, tablets, and laptops.
- Wireless power systems for medical implants and wearable devices.
- Industrial applications for powering mobile robots, drones, or tools in clean or hazardous environments.
- Any inductive power transfer system requiring efficiency optimization without a dedicated communication channel.
