Method and apparatus for controlling wireless induction power supply
The present invention provides a method and an apparatus for controlling the wireless induction power supply. The apparatus comprises a transmitter control circuit and a receiver control circuit. The method comprises generating a plurality of switching signals for switching a transmitter winding and generating a power; detecting a level of a transmitter signal from the transmitter winding; and controlling a switch to deliver the power from a receiver winding to a load. The receiver winding is coupled to receive the power from the transmitter winding. The switching signals will be disabled if the level of the transmitter signal is not higher than a threshold over a first period or the level of the transmitter signal is higher than a high-threshold over a second period. Accordingly, the method and the apparatus according to the present invention have the foreign object detection (FOD) function for the safety.
1. A method for controlling a wireless induction power supply, comprising:
generating a plurality of switching signals for switching a transmitter winding and generating a power;
detecting a level of a transmitter signal from the transmitter winding while the switching signals are enabled and while the power is not delivered to a load for detecting a foreign object, the switching signals remain enabled if the level of the transmitter signal is higher than a threshold, the switching signals are disabled if the level of the transmitter signal is not higher than the threshold for a first time period, and the status of the load is detected as no-load and the switching signals are disabled if the level of the transmitter signal is higher than a high-threshold for a second time period, wherein the high-threshold is greater than the threshold; and
controlling a switch to deliver the power from a receiver winding to the load wherein the receiver winding is coupled to receive the power from the transmitter winding.
2. The method as claimed in claim 1 , wherein if the switching signals are disabled in response to the level of the transmitter signal is not higher than the threshold for the first period, periodically re-enabling the switching signals to detect the level of the transmitter signal.
3. The method as claimed in claim 1 , wherein the switching signals are coupled to drive a plurality of transistors coupled to the transmitter winding; the transistors develop a bridge topology to switch the transmitter winding.
4. The method as claimed in claim 1 , wherein if the switching signals are disabled in response to the level of the transmitter signal is higher than the high-threshold for the second period, re-enabling the switching signals periodically to detect the level of the transmitter signal.
5. The method as claimed in claim 1 , further comprising detecting a level of an input voltage of the wireless induction power supply.
6. The method as claimed in claim 1 , including periodically turning-off the switch to decouple the load from receiving the power wherein the switch is coupled in series between the receiver winding and the load.
7. The method as claimed in claim 6 , including turning-off the switch when the load condition is a no load condition.
8. The method as claimed in claim 1 , wherein the level of the transmitter signal is related to a level of an input voltage of the wireless induction power supply and an impedance of the transmitter winding, the impedance of the transmitter winding becomes lower and the level of the transmitter signal is decreased when the foreign object is coupled to the transmitter winding by a magnetic field of the transmitter winding.
9. The method of claim 1 including configuring the control circuit to control the transmitter winding without receiving a signal from another controller coupled to control the receiver winding.
10. A method for controlling a wireless induction power supply, comprising:
generating a plurality of switching signals for switching a transmitter winding and generating a power;
detecting a level of a transmitter signal from the transmitter winding while the switching signals remain enabled and while not delivering the power to a load for detecting a foreign object, wherein a status of the load is detected as no foreign object is detected and the switching signals continue to be enabled if the level of the transmitter signal is higher than a low-threshold, and the status of the load is detected as no-load and the switching signals are disabled if the level of the transmitter signal is higher than a high-threshold for a first time period; and
controlling a switch to deliver the power from a receiver winding to the load wherein the receiver winding is coupled to receive the power from the transmitter winding.
11. The method as claimed in claim 10 , wherein if the switching signals are disabled in response to the level of the transmitter signal is higher than the high-threshold for the first time period, re-enabling the switching signals periodically to detect the level of the transmitter signal.
12. The method as claimed in claim 10 , wherein the switching signals are coupled to drive a plurality of transistors coupled to the transmitter winding; the plurality of transistors develop a bridge topology to switch the transmitter winding.
13. The method as claimed in claim 10 , wherein the switching signals are disabled if the level of the transmitter signal is not higher than the low-threshold for a second time period.
14. The method as claimed in claim 13 , wherein if the switching signals are disabled in response to the level of the transmitter signal is not higher than the low-threshold for the second time period, re-enabling the switching signals periodically to detect the level of the transmitter signal.
15. The method as claimed in claim 10 , further comprising detecting a level of an input voltage of the wireless induction power supply.
16. The method as claimed in claim 10 , wherein the switch is periodically turned off to decouple the load from receiving the power.
17. The method as claimed in claim 10 , wherein the level of the transmitter signal is related to a level of an input voltage of the wireless induction power supply and an impedance of the transmitter winding, the impedance of the transmitter winding becomes lower and the level of the transmitter signal is decreased when the foreign object is coupled to the transmitter winding by a magnetic field of the transmitter winding.
18. The method as claimed in claim 10 , wherein the switch is turned off when the condition of the load is a no load condition.
19. An apparatus for controlling a wireless induction power supply, comprising:
a transmitter control circuit generating a plurality of switching signals for switching a transmitter winding and generating a power, and detecting a level of a transmitter signal from the transmitter winding while the switching signals remain enabled and while not delivering the power to a load for detecting a foreign object, wherein the foreign object is detected and the switching signals are disabled if the level of the transmitter signal is not higher than a threshold for a first time period, and the status of the load is detected as no-load and the switching signals are disabled if the level of the transmitter signal is higher than a high-threshold for a second time period; and
a receiver control circuit controlling a switch to deliver the power from a receiver winding from to the load wherein the receiver winding is coupled to receive the power from the transmitter winding.
20. The apparatus of claim 19 wherein the transmitter control circuit is configured to disable the switching signals in response to the level of the transmitter signal is less than a low threshold indicating a heavy load condition wherein the low threshold is less than the first threshold and less than the high-threshold.