A Control Circuit With Load-Current Injection for Single-Phase Power-Factor-Correction Rectifiers

A load-current-injection control technique for boost-derived power-factor-correction (PFC) rectifiers with average current-mode control is proposed in this paper. By adding a load-current loop to the conventional inductor current loop, the output voltage response to load steps is speeded up, almost eliminating the typical voltage overshoots of this kind of converters. Although the techniques based on the load-current injection are traditionally called "load feedforward," this paper shows that an additional feedback loop, which modifies the linear small-signal model of the converter, is also introduced. In order to validate the concept, a converter prototype working from a universal input line has been designed and tested, showing that a very fast dynamic response of PFC rectifiers may be achieved in a cost-effective way

Nomenclature

, ,

Current and voltage sensing gains, respectively.

and

Rectified line voltage and rectifier output voltage, respectively.

and

Line voltage and input current, respectively.

Inductor current.

Load current.

Part of that is independent of (load-current disturbance).

Reference voltage.

Gain of the pulsewidth-modulation modulator.

Transfer function of the inductor current regulator.

Transfer function of the voltage regulator.

Loop gain of the inner inductor current loop.

Loop gain of the outer voltage loop.

, , ,

Inputs and output of the multiplier/divider block (both and are current signals in most power-factor-correction integrated circuits).

Reference signal for the inductor current control loop.

. Sensing gain of the rectified input voltage.

. Voltage feedforward gain.

.

Load-current-injection gain.