Method for power calibration

1 . A method of calibrating a power measuring function of a wireless power device, the method comprising:

feeding an alternating electric signal through a wireless power transmitter coil to drive the wireless power transmitter coil at an operating point;

performing voltage measurements and current measurements upon said alternating electric signal or upon a current signal resulting therefrom in the wireless power device;

producing a series of voltage values and a series of current values from the voltage measurements and current measurements;

calculating a power value from the produced series of voltage values and series of current values;

assessing whether the calculated power value meets a specification;

if not, introducing a compensatory change in either of the produced series of voltage values and series of current values to account for a phase shift between the voltage measurements and current measurements at said operating point; and

storing the compensatory change for the wireless power device, thereby enabling the power measuring function thereof to produce wireless power measurement results at said operating point which are consistent with said specification,

wherein:

the wireless power device is a wireless power transmitter device,

the wireless power transmitter coil is comprised in, galvanically coupled to or otherwise associated with the wireless power transmitter device,

all steps of the method are performed by the wireless power transmitter device,

the voltage measurements and current measurements are performed upon the alternating electric signal as fed through the wireless power transmitter coil in the presence of a wireless power receiver coil of a calibrated wireless power receiver device, and

assessing whether the calculated power value meets the specification involves assessing whether it matches, within a specified error margin, a received power value determined by the calibrated wireless power receiver device.

2 . The method as defined in claim 1 , wherein the steps of the method are repeated for a plurality of operating points.

3 . The method as defined in claim 2 , wherein an operating point is defined by one of, or a combination of two or more of, the following:

a fundamental frequency of the alternating electric signal;

harmonic contents of the alternating electric signal;

a load resistance;

a nominal RMS current value of the alternating electric signal;

a nominal RMS voltage value of the alternating electric signal; and

an operating temperature.

4 . The method as defined in claim 1 , further comprising introductory steps of:

independently assessing the ability of the power measuring function of the wireless power device to determine RMS voltage values and RMS current values at a specified accuracy; and

if necessary, calibrating the power measuring function of the wireless power device.

5 . The method as defined in claim 1 ,

wherein the series of voltage values is a time series produced by sampling, at a sampling rate, of the voltage measurements as obtained by voltage measurement circuitry of the wireless power device, and

wherein the series of current values is a time series produced by sampling, at said sampling rate, of the current measurements as obtained by current measurement circuitry of the wireless power device.

6 . The method as defined in claim 5 , wherein the compensatory change is introduced by applying an artificial delay ε to one of said time series of current values or voltage values, such that for an original time series i(n)=i(t) or v(n)=v(t) for every t=k·T sample , where T sample is the inverse of the sampling rate, the artificial delay ε is applied to yield a compensated time series i(n)=i(t+ε) or v(n)=v(t+ε).

7 . The method as defined in claim 6 , wherein the artificial delay ε is applied to said one time series of current values or voltage values such that the RMS value thereof remains unchanged and the electric power value calculated from the compensated time series and the other time series of current values or voltage values meets or becomes closer to said specification.

8 . A method of calibrating a power measuring function of a wireless power device, the method comprising:

feeding an alternating electric signal through a wireless power transmitter coil to drive the wireless power transmitter coil at an operating point;

performing voltage measurements and current measurements upon said alternating electric signal or upon a current signal resulting therefrom in the wireless power device;

producing a series of voltage values and a series of current values from the voltage measurements and current measurements;

calculating a power value from the produced series of voltage values and series of current values;

assessing whether the calculated power value meets a specification;

if not, introducing a compensatory change in either of the produced series of voltage values and series of current values to account for a phase shift between the voltage measurements and current measurements at said operating point; and

storing the compensatory change for the wireless power device, thereby enabling the power measuring function thereof to produce wireless power measurement results at said operating point which are consistent with said specification,

wherein:

the wireless power device is a wireless power receiver device with a wireless power receiver coil comprised in, galvanically coupled to or otherwise associated therewith,

the wireless power transmitter coil is comprised in, galvanically coupled to or otherwise associated with a wireless power transmitter device,

the feeding step is performed by the wireless power transmitter device,

all other steps of the method are performed by the wireless power receiver device,

the voltage measurements and current measurements are performed upon a resulting alternating electric signal received through the wireless power receiver coil of the wireless power receiver device in response to said alternating electric signal being fed through the wireless power transmitter coil, and

assessing whether the calculated power value meets the specification involves assessing whether it falls within a specified error margin from a transmitted power value determined by the wireless power transmitter device.

9 . The method as defined in claim 8 , wherein the steps of the method are repeated for a plurality of operating points.

10 . The method as defined in claim 9 , wherein an operating point is defined by one of, or a combination of two or more of, the following:

a fundamental frequency of the alternating electric signal;

harmonic contents of the alternating electric signal;

a load resistance;

a nominal RMS current value of the alternating electric signal;

a nominal RMS voltage value of the alternating electric signal; and

an operating temperature.

11 . The method as defined in claim 8 , further comprising introductory steps of:

independently assessing the ability of the power measuring function of the wireless power device to determine RMS voltage values and RMS current values at a specified accuracy; and

if necessary, calibrating the power measuring function of the wireless power device.

12 . The method as defined in claim 8 ,

wherein the series of voltage values is a time series produced by sampling, at a sampling rate, of the voltage measurements as obtained by voltage measurement circuitry of the wireless power device, and

wherein the series of current values is a time series produced by sampling, at said sampling rate, of the current measurements as obtained by current measurement circuitry of the wireless power device.

13 . The method as defined in claim 12 , wherein the compensatory change is introduced by applying an artificial delay ε to one of said time series of current values or voltage values, such that for an original time series i(n)=i(t) or v(n)=v(t) for every t=k·T sample , where T sample is the inverse of the sampling rate, the artificial delay ε is applied to yield a compensated time series i(n)=i(t+ε) or v(n)=v(t+ε).

14 . The method as defined in claim 13 , wherein the artificial delay ε is applied to said one time series of current values or voltage values such that the RMS value thereof remains unchanged and the electric power value calculated from the compensated time series and the other time series of current values or voltage values meets or becomes closer to said specification.

15 . A method of calibrating a power measuring function of a wireless power device, the method comprising:

feeding an alternating electric signal through a wireless power transmitter coil to drive the wireless power transmitter coil at an operating point;

performing voltage measurements and current measurements upon said alternating electric signal or upon a current signal resulting therefrom in the wireless power device;

producing a series of voltage values and a series of current values from the voltage measurements and current measurements;

calculating a power value from the produced series of voltage values and series of current values;

assessing whether the calculated power value meets a specification;

if not, introducing a compensatory change in either of the produced series of voltage values and series of current values to account for a phase shift between the voltage measurements and current measurements at said operating point; and

storing the compensatory change for the wireless power device, thereby enabling the power measuring function thereof to produce wireless power measurement results at said operating point which are consistent with said specification,

wherein the method further comprises introductory steps of:

independently assessing the ability of the power measuring function of the wireless power device to determine RMS voltage values and RMS current values at a specified accuracy; and

if necessary, calibrating the power measuring function of the wireless power device.