US 9,812,971 B1
Transformer flux estimation and limiting in isolated DC-DC voltage converters
Darryl Tschirhart, Torrance, CA (US); and Amir Babazadeh, Laguna Hills, CA (US)
Assigned to Infineon Technologies Austria AG, Villach (AT)
Filed by Infineon Technologies Austria AG, Villach (AT)
Filed on Aug. 12, 2016, as Appl. No. 15/235,872.
Int. Cl. H02M 3/335 (2006.01); H02M 1/32 (2007.01); G01R 33/12 (2006.01); H02M 3/156 (2006.01)
CPC H02M 3/33507 (2013.01) [G01R 33/12 (2013.01); H02M 1/32 (2013.01); H02M 3/156 (2013.01)] 34 Claims
OG exemplary drawing
 
1. A voltage converter, comprising:
a power stage coupled to an input power source, the power stage comprising one or more power switches;
a transformer comprising a primary winding coupled to the power stage, and a secondary winding;
a conditioning circuit coupling the secondary winding to an output node that is operable to supply power to a load of the voltage converter; and
a controller operable to:
generate pulse-width modulated (PWM) waveforms for controlling the one or more power switches, wherein each of the PWM waveforms is comprised of a series of PWM pulses;
estimate magnetic flux within the transformer based upon at least one of a voltage across the primary winding and a voltage within the conditioning circuit;
detect an overflux condition in which a magnitude of an estimated magnetic flux has exceeded a flux magnitude limit for the transformer; and
responsive to detecting the overflux condition, truncate a pulse within the series of PWM pulses of the PWM waveforms before the PWM waveforms are provided to the one or more power switches.