Average input current estimation based on primary side current sense

摘要

The embodiments herein describe a power converter including a controller that estimates input current of the power converter. The controller estimates the input current without explicitly sensing the input current. The estimated input current can be used in various applications such as regulating power factor and total harmonic distortion as well as estimating current required to maintain proper operation of a dimmer switch in light emitting diode lamp systems.

主权项

1. A switching power converter comprising:
a magnetic component coupled to an input voltage and an output of the switching power converter; a switch coupled to the magnetic component to control current through at least part of the magnetic component, current through at least the part of the magnetic component generated while the switch is turned on and not being generated while the switch is turned off; a controller including a pin for sensing the current through at least the part of the magnetic component, the controller configured to generate a control signal to turn on or turn off the switch during a plurality of switching cycles of the switch; a resistive voltage divider including a first resistor and a second resistor, the current through at least the part of the magnetic component flows through the first resistor but not through the second resistor; and wherein the controller is configured to estimate an average input current of the switching power converter based on the following equation:Iin_avg=12·DISENSERSNS·TonTPwhere Iin—avg is the estimated average input current, DISENSE is a value representing a target peak current through at least the part of the magnetic component, RSNS is an impedance of the first resistor, Ton is an on-time of the switch during a switching cycle of the power converter, and Tp is a period of the switching cycle.