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4. Working Principle of the Major Functional Block
4.1 Switch Power Supply
The Switch Power Supply (SPS) supplies DC power for Inverter operation including
+5V,+12V,-12V and +15V.
The SPS consists 3 parts: the battery SPS, the grid SPS and main SPS. The battery SPS
generates a DC voltage at about 120Vdc(BATSPS) and the grid SPS generates a DC
voltage about 150Vdc(ACSPS).
The input source of the main SPS can be any of the DC
BUS voltage, the output of the battery SPS or the output of the grid SPS. Because the PV
input can power to the DC BUS through a diode, any of 3 inverter power sources: PV, grid,
battery is good, the main SPS works and supplies the DC power +5V,+12V,-12V and
+15V.
Figure 4.1 Basic circuit of battery SPS
Figure 4.2 Basic circuit of grid SPS
Figure 4.3 Basic circuit of main SPS
Figure 4.1, Figure 4.2 and Figure 4.3 are the basic circuits of battery SPS, grid SPS and