In the simulation circuit as the figure 8,
to join the PI control in inverter feedback control.
Inverter current compared
with a given current value, the error after the PI controller
generates PWM signals that it can control on and off to the
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main circuit, thus to control the inverter circuit. The grid
voltage waveform and inverter voltage waveform and the grid
current are shown in figure 9 and figure 10 and figure 11.