Experimental test results
AN4070
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Doc ID 022934 Rev 1
and the DC-AC converter to be adjusted by acting on the duty cycle and modulating index
respectively. The duty cycle has been adjusted to obtain a DC bus voltage of 390 V and the
modulating index in order to get 230 V AC on the output for each test point. The efficiency
characterization of the DC-DC converter and of the system is shown in
Figure 28
and
29
respectively. The peak system efficiency is about 94% and the CEC efficiency is 93.4%.
While
Figure 27
shows the MIC output waveforms when operating in open loop mode,
Figure 30
shows the same waveforms when the system is operating at nominal power in
closed loop mode and grid connection. In these operating conditions the current THD is
2.8%. When operating in grid connection, the current THD is higher and equal to 4.8% at full
load while the power factor is equal to 0.92.
Figure 30
shows the current and voltage
waveforms during grid connected operation. It is worth noting that the PLL signal (yellow
track) is synchronized with the peak of the grid voltage. Finally,
Figure 31
and
32
show the
variation of output current THD and power factor across the operating profile of the system.
Figure 27.
DC-AC converter output voltage and current waveforms
