US 11,990,781 B2
Method for determining a quality factor and wireless charger
Dechang Wang, Suzhou (CN); Dengyu Jiang, Suzhou (CN); Ruyang Sheng, Suzhou (CN); and Huan Mao, Suzhou (CN)
Assigned to NXP USA, Inc., Austin, TX (US)
Filed by NXP USA, Inc., Austin, TX (US)
Filed on Nov. 25, 2020, as Appl. No. 17/104,163.
Claims priority of application No. 201911254542.0 (CN), filed on Dec. 6, 2019.
Prior Publication US 2021/0175728 A1, Jun. 10, 2021
Int. Cl. H02J 7/00 (2006.01); G01R 27/26 (2006.01); H02J 7/04 (2006.01); H02J 50/12 (2016.01)
CPC H02J 7/0047 (2013.01) [G01R 27/2688 (2013.01); H02J 7/04 (2013.01); H02J 50/12 (2016.02); H02J 2207/20 (2020.01)] 20 Claims
OG exemplary drawing
 
1. A method for determining a quality factor of a wireless charger, wherein the wireless charger comprises an inverter configured to receive a supply voltage and generate a PWM signal by switching first, second, third, and fourth switches of the inverter, a filter connected to the inverter and configured to receive the PWM signal and generate a filtered signal, and a resonant tank circuit connected to the filter and configured to receive the filtered signal and provide wireless power to a receiver in a wireless charging phase of the wireless charger, wherein the method comprises:
controlling the first, second, third, and fourth switches to place the wireless charger in the wireless charging phase before entering a Q-factor determination phase of the wireless charger;
entering the Q-factor determination phase; and
while in the Q-factor determination phase, stopping switching of the first, second, third, and fourth switches, followed by issuing a single current pulse to the resonant tank circuit by closing one of the first and the second switches, and immediately after issuing the single current pulse, opening the first to fourth switches for a remaining duration of the Q-factor determination phase prior to controlling the first, second, third, and fourth switches to alternately close the first and second switches and alternately close the third and fourth switches.