Introduction - Control of Power Inverters in Renewable Energy and Smart Grid Integration - page 10

L

i L D i o

v L -

+

D 1 D 3

i s

i c

+

~ Q C Load

v o

v s

-

D 4 D 2

(a) Topology

v s

|sin( ω t)|

ω t

STA

|sin|

v oref

Q

Hysteresis
Controller

×

PI

-

-

v o

i L

(b) Basic control strategy

i L

v s

i s

i o

0 0

π 2π 3π 4π π 2π 3π 4π

ωt/rad ωt/rad

(d) i L and i o

(c) Input voltage and input current

Figure 1.10 Diode rectifier cascaded with a boost converter

inductor current is a rectified full wave. Note that because of the boosted output voltage, the
load current is less than the average of the inductor current.
The hysteresis controller produces PWM pulses to turn on/off the switch Q according to the
difference between the current i L and its reference, which is in phase with the output voltage
of the diode rectifier (and hence the input voltage). As a result, the actual current i L always
tracks the reference current within a hysteresis band (Bose 2001) and the input current is in
phase with the input voltage. The relevant curves are shown in Figures 1.10(c) and 1.10(d).
In order to obtain the phase information of the supply, an STA is adopted; see Chapter 22
for more details.