User`s guide

SMPS AC/DC REFERENCE

DESIGN USER’S GUIDE

Chapter 2. Hardware Design

This chapter provides a functional overview of the SMPS AC/DC Reference Design

and identifies the major hardware components. Topics covered include:

• PFC Boost Converter

• Full-Bridge ZVT Converter

• Single-Phase Synchronous Buck Converter

• Three-Phase Synchronous Buck Converter

• Auxiliary Power Supply

2.1 PFC BOOST CONVERTER

The conventional single-phase power factor correction circuit is a standard Boost

converter topology operating from the full wave rectified mains input, as shown in

Figure 2-1.

The converter controller has an inner current control loop and outer voltage control

loop. The current reference waveform is the input rectified mains voltage, so that the

resultant current drawn from the mains is essentially sinusoidal and in-phase with the

mains voltage. The amplitude of the current is controlled by the duty cycle of the fixed

frequency PWM of the MOSFET, and is controlled by the PWM reference, which is the

product of the current reference and the output of the DC link voltage error amplifier.

Refer to Chapter 1. “Introduction” for details on the operation of this converter.

FIGURE 2-1: PFC POWER CONVERTER

EQUATION 2-1:

EQUATION 2-2:

VDC

VAC

()

(

)

=−

100

THD

−