US 12,255,537 B2
Feedforward compensation for LLC resonant converters
Halladi Shashwatha Kumara Kedlaya, Udupi (IN); and Piyush Nilchandra Waghmare, Kundalhalli (IN)
Assigned to Hamilton Sundstrand Corporation, Charlotte, NC (US)
Filed by Hamilton Sundstrand Corporation, Charlotte, NC (US)
Filed on Jun. 7, 2022, as Appl. No. 17/833,966.
Claims priority of application No. 202141025329 (IN), filed on Jun. 7, 2021.
Prior Publication US 2022/0393602 A1, Dec. 8, 2022
Int. Cl. H02M 3/335 (2006.01); H02M 1/00 (2006.01); H02M 3/00 (2006.01)
CPC H02M 3/33571 (2021.05) [H02M 1/0016 (2021.05); H02M 3/01 (2021.05)] 20 Claims
OG exemplary drawing
 
1. An LLC resonant converter comprising:
an LLC resonant converter circuit comprising:
an output line;
an input line;
first and second capacitors coupled in series, the first capacitor coupled to the input line;
first and second switches coupled in series, the first switch coupled to the input line, the first and second switches forming a switch array operatively connected between the input line and the output line; and
first and second inductors coupled in series, the first inductor coupled between the first and second switches, the second inductor coupled between the first and second capacitors; and
a controller connected to the input line by a feed-forward line and connected to a respective gate of each of the first and second switches, wherein the controller includes machine readable instructions configured to cause the controller to:
receive feed-forward input from the input line and control switching of the switch array with a pulse frequency modulation (PFM) switching pattern to regulate an output voltage of the output line;
take a difference of a reference voltage minus a feedback transfer function of the output voltage of the output line to produce an error signal, wherein the feedback transfer function is expressed as

OG Complex Work Unit Math
 where Vref is the reference voltage and Vo is the output voltage; and
take a difference of a controller transfer function of the error signal minus a feed-forward compensator transfer function of an input voltage of the input line to produce a switching frequency signal, wherein the feed-forward compensator transfer function is expressed as

OG Complex Work Unit Math
where K is a feed-forward compensator gain, s is a complex variable (continuous time-domain), and wp is a feed-forward compensator pole frequency.