US 12,289,058 B2
Synchronous flyback converter circuit
Reimar Klotz, Dornbirn (AT)
Assigned to Tridonic GmbH & Co KG, Dornbirn (AT)
Appl. No. 17/439,913
Filed by TRIDONIC GMBH & CO KG, Dornbirn (AT)
PCT Filed Mar. 20, 2020, PCT No. PCT/EP2020/057805
§ 371(c)(1), (2) Date Sep. 16, 2021,
PCT Pub. No. WO2020/188091, PCT Pub. Date Sep. 24, 2020.
Claims priority of application No. 10 2019 107 225.5 (DE), filed on Mar. 21, 2019.
Prior Publication US 2025/0015727 A1, Jan. 9, 2025
Int. Cl. H02M 3/335 (2006.01); H02M 1/00 (2006.01); H02M 3/07 (2006.01)
CPC H02M 3/33592 (2013.01) [H02M 1/0009 (2021.05); H02M 3/07 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A flyback converter circuit (3) comprising:
a first controllable switch (8) having a parasitic or an external capacitor (14) that is connected in parallel;
a second controllable switch (11);
a transformer (7) with a primary winding (6) which is electrically connected to the first switch (8) and a secondary winding (10) which is electrically connected to the second switch (11);
a controller (13) which is configured to switch off the first switch (8) at a point in time and switch on the second switch, the capacitor being charged, and to switch off the second switch (11) when the current through the second switch (11) has reached a negative value after it has decreased to zero, the capacitor (14) being discharged after the second switch (11) is switched off; and
means (15) for ascertaining a measure of the discharge rate of the capacitor (14) in order to determine the current flowing through the second switch (11) at the point in time when the second switch is switched off;
wherein the controller (13) is configured to control at least the first switch (8) on a basis of the determined current.