Introduction - Control of Power Inverters in Renewable Energy and Smart Grid Integration - page 11

1.2.1.4 PWM-controlled Rectifiers

A diode rectifier cascaded with a boost converter is able to improve the quality of the input
current but the power flow is unidirectional from the source to the load. In order to solve this
problem, a bidirectional converter with fully PWM-controlled power switches can be adopted.
A PWM-controlled rectifier can be operated as a rectifier or an inverter and the power can
flow from the AC side to the DC side or from the DC side to the AC side, if there is energy
available at the DC side.
Figure 1.11(a) shows a PWM-controlled single-phase H-bridge rectifier. It is basically
operated as a boost converter so an inductor is connected to the input voltage side. A basic
control strategy is shown in Figure 1.11(b), which makes the input current in phase with the

i o

+

Q 1 Q 3

i s

L

~

v o

v s

C

Q 2

Q 4

-

(a) Topology

v s

sin( ω t)

ω t

STA sin

Q 1

Hysteresis
Controller

Q 4

-

v oref

i s

×

PI

Q 3

-

-

Hysteresis
Controller

v o

Q 2

(b) Basic control strategy

v s

i s

0 π 2 π 3 π 4 π 0 π 2 π 3 π 4 π

ω t/rad ω t/rad

(c) Input voltage and current (d) Output voltage

Figure 1.11 PWM-controlled single-phase full-bridge rectifier