Hysteretic power factor control method for single stage power converters

摘要

In one aspect, a switching power converter is described that includes a transformer, a switch, and a controller that generates a control signal to turn on and turn off the switch. For each alternating current (AC) half-cycle of an input voltage, the controller determines a minimum value of a signal representing an on-time of the power converter, compares the determined minimum value with a threshold value that is used to determine whether the switching power converter operates in a constant on-time mode or in a constant power mode, and adjusts the threshold value based on a result of the comparison. The controller further generates the control signal to operate the switching power converter in a constant power mode during a first time period of the AC half-cycle, the first time period representing a duration where the threshold value is larger than an instantaneous value of the first signal.

主权项

1. A switching power converter comprising:
a transformer including a primary winding coupled to an input voltage and a secondary winding coupled to an output of the switching power converter; a switch coupled to the primary winding of the transformer, current passing through the primary winding while the switch is turned on and not passing through while the switch is turned off; a controller configured to generate a control signal to turn on and turn off the switch at each of a plurality of switching cycles of the switch; wherein for each alternating current (AC) half-cycle of the input voltage, the controller is further configured to:
determine a minimum value of a first signal representing an on-time of the switching power converter,compare the determined minimum value with a threshold value of the first signal, the threshold value is used to determine whether the switching power converter operates in a constant on-time mode or in a constant power mode, andadjust the threshold value by increasing or decreasing the threshold value based on a result of the comparison; and wherein the controller generates the control signal to operate the switching power converter in a constant power mode during a first time period of the AC half-cycle, the first time period representing a duration where the threshold value is larger than an instantaneous value of the first signal.