As previously highlighted, a good dynamic behavior is required in order to take into account the loading effect of the power converter supplied by the PV emulator.
The possibility to impose the closed-loop poles, by using the pole placement technique, described in Sect. 8.4, permits to obtain a fast dynamical response.
The output impedance of the DC/DC converter gives information on the range of frequencies in which the PV emulator behaves like an ideal voltage source.
As previously said, a low impedance value is desirable in order to correctly reproduce the current demand coming from the loading converter.
The closed-loop poles are chosen as a pair of complex and conjugate and a real one. The corresponding kt coefficients are chosen equal to k12 = 2я(500 ± j500) and k3 = 2я500. This choice assures a dynamical response with a rise time in the order of milliseconds.
The equivalent output capacitance corresponds to about 10 iF that is smaller than a typical expected load capacitance.
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Fig. 8.18 Implemented model of the PV emulator |
The obtained output impedance versus frequency curve, calculated by Eqs. (8.34) and (8.35), is shown in Fig. 8.17. It is possible to observe that it exhibits a maximum equal to 2.25 X at 1.6 kHz (104 rad/s).
