US 11,728,690 B2
Foreign object detection using wireless power receiver's response to modified transmitter behavior
Nicholaus Smith, La Mesa, CA (US); Gustavo Mehas, Mercer Island, WA (US); and Tao Qi, San Diego, CA (US)
Assigned to Renesas Electronics America Inc., Milpitas, CA (US)
Filed by Renesas Electronics America Inc., Milpitas, CA (US)
Filed on Jun. 29, 2020, as Appl. No. 16/915,940.
Prior Publication US 2021/0408836 A1, Dec. 30, 2021
Int. Cl. H02J 50/60 (2016.01); H02J 50/12 (2016.01); H02J 50/90 (2016.01); H02J 50/80 (2016.01)
CPC H02J 50/60 (2016.02) [H02J 50/12 (2016.02); H02J 50/80 (2016.02); H02J 50/90 (2016.02)] 20 Claims
OG exemplary drawing
 
1. A system comprising a wireless power transmitter for performing a wireless power transfer (WPT) operation, the system comprising:
an input for receiving power;
a transmit coil;
a circuit configured to generate an AC power signal in the transmit coil from power received at the input in order to perform WPT from the transmitter to a wireless power receiver in the WPT operation, the circuit comprising a controller configured to operate the transmitter to:
(A) perform normal operation in which the transmitter generates the AC power signal to transmit power to the wireless power receiver, wherein in normal operation:
the transmitter receives feedback messages from the wireless power receiver; and
the transmitter adjusts the AC power signal in correspondence with the feedback messages;
(B) interrupt the normal operation to perform one or more foreign object detection (FOD) tests to detect FO interference, wherein each FOD test comprises a first operation, a second operation, and a third operation, and in each FOD test:
in the first operation, the transmitter changes the AC power signal not to correspond to the feedback messages; then
in the second operation, the transmitter receives one or more new feedback messages from the wireless power receiver; and
in the third operation, the transmitter determines whether or not the one or more new feedback messages match the AC power signal change in the first operation to indicate presence or absence of a foreign object.