US 12,142,931 B1
Pulse width modulated inverter control with multi-state signaling
Jose V Santos Martinez, San Jose, CA (US); and Yongxuan Hu, San Jose, CA (US)
Assigned to Apple Inc., Cupertino, CA (US)
Filed by Apple Inc., Cupertino, CA (US)
Filed on Jun. 1, 2022, as Appl. No. 17/804,918.
Claims priority of provisional application 63/268,823, filed on Mar. 3, 2022.
Int. Cl. H02J 50/00 (2016.01); H02J 50/12 (2016.01); H02M 7/5395 (2006.01)
CPC H02J 50/005 (2020.01) [H02J 50/12 (2016.02); H02M 7/5395 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A wireless power transmitter comprising:
a wireless power transmitter coil adapted to magnetically couple the wireless power transmitter to a wireless power receiver;
a resonant capacitor coupled to the wireless power transmitter coil to form a resonant circuit; and
an inverter having an input that receives a DC voltage and an AC output coupled to the resonant circuit, the inverter further comprising:
a plurality of switching devices coupled between the input and AC output of the inverter;
a controller configured to generate pulse width modulated (PWM) drive signals for the plurality of switching devices, wherein the PWM drive signals are tri-state PWM signals having three output levels; wherein:
in a first state of a tri-state PWM signal corresponding to a first output level of the three output levels, the corresponding switching device is turned off;
in a second state of the tri-state PWM signal corresponding to a second output level of the three output levels, the corresponding switching device is forced on in a hard switching event; and
in a third state of the tri-state PWM signal corresponding to a third output level of the three output levels, the corresponding switching device is allowed to turn on in a soft switching event upon occurrence of a zero crossing of the voltage across the corresponding switching device; and
circuitry that receives the PWM drive signals for corresponding switching devices and signals corresponding to voltages across the corresponding switching devices and generates gate drive signals for the corresponding switching devices.