Nonlinear system identification for optimization of wireless power transfer
A method of detecting whether a receiver coil is near a transmit coil in a wireless power transfer system (WPTS), the method involving: applying a pseudo-random signal to the transmit coil; while the pseudo-random signal is being applied to the transmit coil, recording one or more signals produced within the WPTS in response to the applied pseudo-random signal; by using the one or more recorded signals, generating a dynamic system model for some aspect of the WPTS; and using the generated dynamic system model in combination with stored training data to determine whether an object having characteristics distinguishing the object as a receiver coil is near the transmit coil.
1. A method of finding an operating frequency for a drive signal to a transmit coil in a wireless power transfer system (WPTS), said method comprising:
applying a pseudo-random signal to the transmit coil;
while the pseudo-random signal is being applied to the transmit coil, recording one or more signals produced within the WPTS in response to the applied pseudo-random signal;
by using the one or more recorded signals, generating a dynamic system model for some aspect of the WPTS; and
conducting a search for an optimum frequency for the drive signal, wherein conducting the search comprises repeatedly using the generated dynamic system model to simulate a response to the drive signal while varying the operating frequency of the drive signal until the optimum frequency is found.
2. The method of claim 1 , wherein conducting a search further comprises:
computing an output power from the simulated response;
using the computed output power as an objective function; and
conducting the search by using the objective function.
3. The method of claim 1 , further comprising setting the operating frequency of the drive signal to the optimum frequency.
4. The method of claim 1 , wherein the pseudo-random signal is a pseudo-random voltage signal.
5. The method of claim 4 , wherein the one or more signals includes a current signal of the transmit coil.
6. The method of claim 4 , wherein the one or more signals includes a current signal and a voltage signal of the transmit coil.
7. The method of claim 1 , wherein generating the representation of the transfer function comprises using system identification to fit a model to data derived from the one or more recorded signals.
8. The method of claim 1 , wherein generating the dynamic system model comprises using nonlinear system identification to fit a selected model to the data derived from the one or more recorded signals.
9. The method of claim 8 , wherein the selected model is a Wiener system.
10. The method of claim 8 , wherein the selected model has a dynamic linear part and a static nonlinear part.
11. The method of claim 1 , wherein the generated dynamic system model comprises a time domain representation.
12. The method of claim 1 , wherein the generated dynamic system model comprises a frequency domain representation.
13. A wireless power transfer system comprising:
a transmit coil;
a power transmitter circuit connected to the transmit coil;
a sensor circuit connected to the transmit coil; and
a controller for controlling the power transmitter circuit and the sensor circuit, wherein said controller includes a memory for storing training data and a processor system programmed to:
cause the power transmitter to apply a pseudo-random signal to the transmit coil;
while the pseudo-random signal is being applied to the transmit coil, cause the sensor circuit to record one or more signals produced within the WPTS in response to the applied pseudo-random signal;
by using the one or more recorded signals, generate a dynamic system model for some aspect of the WPTS; and
conduct a search for an optimum frequency for the drive signal, wherein conducting the search comprises repeatedly using the generated dynamic system model to simulate a response to the drive signal while varying the operating frequency of the drive signal until the optimum frequency is found.