European Journal of Scientific Research - EuroJournals

895 K. G. Firouzjah, H. Eshaghtabar, A. Sheikholeslami and S. Lesan
Figure 3: Three-phase DC to AC inverter with Three-phase load.
3. Predictive Current Control (PCC) in Single Phase Converter
Fig. 4 shows the topology of single phase full-bridge converter with nonlinear Inductive-Resistive
load. Nonlinear treatment of load is modeled in the form of (e) potential. According to the Fig. 4, the
current direction is being selected conventionally in a fix direction. If switching of converter selected
as bipolar control, the switching states will be:
State 1 → S 1,S 4: on S 2,S 3:
off
State 2 → S 2,S 3: on S 1,S 4:
off
Therefore, the duty cycle of S1,S4 switches (D) can be defined. While S1,S4 and S2,S3 are ON,
the load voltage will be equal to Vd and -Vd respectively.
Ton1,4
D =
T
(1)
Ton is the time that S1,S4 are ON in a period (T). So, in a sample the mean value of load voltage
is equal to 2D-1, that:
di
(2D − 1) Vd= Ri + L + e
dt
(2)
While S2,S3 are ON, the duty cycle is D'. According to the bipolar switching technique of single
phase converter:
D= 1−
D′
(3)
By rewriting these equations in discrete time domain we have:
( i( n+ 1) i(
n)
)
(2D( n) -1) V d Ri( n) L e(
n)
T
−
= + +
(4)
D
( n )
( i( n+ 1) i(
n)
)
( n) ( n) d
−
+ + +
Ri L e V
=
T
2 V
d
Figure 4: Single phase full-bridge converter with nonlinear load
(5)