Predictive Control of Three Phase AC/DC Converters

5.1. ROBUSTNESS TO PARAMETERS MISMATCH 79
mainly on switching frequency and load value (Fig. 5.3), however large error in
power ∆S could be observed (Fig. 5.2). In opposite case, when the L C value is
too high (∆L > 0) the current ripples increase. It is caused by higher converter
voltage generated by predictive controller, which tries to reduce voltage drop on
oversized inductance L C . As it can be seen, in all cases CSF approach is more
robust to L mismatch than variable switching frequency.
5.1.2 Filter‘s Resistance Variations
Figure 5.4 shows average switching frequency F swAV in VSF-P-DPC method for
1 and 2 kW of load versus choke resistance value mismatch, used in predictive
model R C . Choke resistance mismatch ∆R is defined as:
∆R = R C − R
100[%] (5.3)
R
where R C is resistance used in predictive algorithm, and R is real value. Figure 5.5
shows calculated power error ∆S (eq. 5.2) versus ∆L whereas, Fig. 5.6 shows
T HD i factor variation under R mismatch.
5
4.5
4
3.5
F swAV
[kHz]
3
2.5
2
1.5
1
2 kW
1 kW
0.5
0
−100 −50 0 50 100
∆ R [%]
Figure 5.4: Average switching frequency F swAV versus line choke resistance value
mismatch ∆R in VSF-P-DPC
As it can be seen in Fig. 5.4 – 5.6, R mismatch does not have influence
on control performance. The voltage drop on choke resistance is much less than
voltage drop on choke inductance. Therefore, for further investigations R changes
will not be performed.