2
verter stage. It converts the high voltage DC into 115 volts, 60
Hz or 50 Hz AC.
The DC-to-DC converter stage uses modern high frequency
power conversion techniques that eliminate the bulky trans-
formers found in inverters based on older technology. The in-
verter stage uses advanced power MOSFET transistors in a full
bridge configuration. This gives you excellent overload capa-
bility and the ability to operate tough reactive loads like lamp
ballasts and small induction motors.
DC-DC CONVERTER
DC
INPUT
+
-
CHASSIS GND
GND
NEUT
LINE
POWER
MOSFET
115 VAC
145 VDC
INVERTER SECTION
AC OUTPUT
+
Figure 1. PROwatt 250 - Principle of Operation
2.2 PROwatt 250 output waveform
The AC output waveform of the PROwatt 250 is called a
“quasi-sine wave” or a “modified sine wave.” It is a stepped
waveform that is designed to have characteristics similar to the
