Power Converters with Digital Filter Feedback Control

Chapter 4

Flyback Converter with Current-Mode Control

Abstract

Following a similar spirit as Chapter 2, peak current-mode control is elected to replace the voltage-mode implementation given in Chapter 3. Once again, the key step in this chapter lies in the derivation of the current-mode PWM gain. Once it is developed, all other procedures almost follow the same sequence as those of Chapter 2.

Keywords

current-mode

current loop

transfer function

gain margin

phase margin

loop gain

bilinear transform

digital filter

4.1. Current-mode schematic

To obtain peak current-mode control, the voltage-mode PWM in Figure 3.3 is replaced by a resistive current sensor R_s, a noninverting scaling amplifier (gain A_c), a comparator, and an RSFF (Figure 4.1).

Figure ...