Frequency controlled dummy load to stabilize PFC operation at light load conditions

摘要

A system and a method offset the effect of a reduced load current on a power factor controller connected to a DC-to-DC converter having a switching DC-to-AC inverter driving an output rectifier that produces the load current. A frequency-dependent load impedance is coupled to the output of the inverter. The frequency-dependent load impedance is configured to have a first impedance when the inverter is operating at the minimum operating frequency. The frequency-dependent load impedance has a second impedance when the inverter is operating at the maximum operating frequency. The second impedance is lower than the first impedance and produces a dummy load current that is added to the actual load current to provide a sufficient total load current to cause the power factor controller to operate in a continuous mode even when the actual load current is insufficient to cause the power factor controller to operate in a continuous mode.