Method for detecting and identifying a receiver in an inductive power transfer system
View Patent ↗A method for detecting the presence of a receiver in an inductively coupled power transfer system having a transmitter and receiver. The method includes switching on a transmitter converter at a first frequency, measuring the inrush current and determining whether there is a receiver present. In another method, the inrush current is measured for a range of transmitter frequencies, and the variation in current is used to determine where there is a receiver present. In another method, the inrush current is measured when there is a change in voltage in the transmitter, and the variation in current is used to determine where there is a receiver present. In another method, the current supplied to the transmitter converter is measured over two transmitter frequencies, and the variation in current is used to determine where there is a receiver present. In another method, the current supplied to the transmitter converter is measured over two transmitter voltages, and the variation in current is used to determine where there is a receiver present.
1. A method for detecting a conducting non-receiver in an inductively coupled power transfer system, the system including a transmitter comprising:
a. an inductor for generating an alternating magnetic field;
b. a converter for supplying an alternating current to the inductor; and
c. a sensor for measuring the current supplied to the converter, including the steps of:
i. supplying current to the inductor so that it generates an alternating magnetic field of a first frequency that resonates with a receiver that may be present;
ii. measuring a first current supplied to the converter;
iii. supplying current to the inductor so that it generates an alternating magnetic field of a second frequency that still substantially resonates with a receiver that may be present;
iii. measuring a second current supplied to the converter
iv. comparing the change in inductor frequency to the change in measured current; and
v. detecting a conducting non-receiver on the basis of the comparison.
2. The method as claimed in claim 1 , wherein the inductor is a coil.
3. The method as claimed in claim 1 , wherein the converter is connected to a controller.
4. The method as claimed in claim 3 , wherein the controller controls the converter to supply an alternating current of a desired frequency.
5. The method as claimed in claim 1 , wherein the converter is a non-resonant half bridge converter.
6. The method as claimed in claim 1 , wherein the first frequency is between 100 and 1000 kHz.
7. The method as claimed in claim 1 , wherein the second frequency is less than 4% different than the first frequency.
8. The method as claimed in claim 1 , wherein the method includes the step of measuring the current supplied to the converter for a plurality of frequencies between the first frequency and the second frequency.
9. The method as claimed in claim 1 , wherein the sensor measures the magnitude of the steady state current.
10. The method as claimed in claim 1 , wherein the sensor is connected to a controller.
11. The method as claimed in claim 10 , wherein the controller determines that there is a conducting non-receiver present if there is an inverse relationship between the magnitude of the measured current and the inductor frequency.
12. The method as claimed in claim 1 , wherein the method includes proceeding with the further step, on the basis of the result of step (v) of claim 1 , of one or more of:
i. continuing to control the converter so that power is transmitted to the receiver;
ii. conducting further tests to verify the presence of a receiver;
iii. conducting further tests to identify whether the receiver is a receiver that is compatible with the inductively coupled power transfer system,
iv. switching the transmitter to a standby mode; or
v. switching the transmitter off.