3.0 THEORY OF OPERATION
MAXX SST™ inverters change 12VDC into 110/120VAC RMS, electrical power.
This is accomplished in two steps. (See
FIGURE 4
).
The first stage raises the 12VDC input to 145VDC. The advanced design
of the DC-to-DC first stage uses high-frequency conversion techniques
that replace bulky and heavy transformers found in older inverter technology. The
output stage changes the 145VDC to 110/120VAC. This solid-state circuitry
ensures excellent overload protection and the ability to operate reactive loads such
as those found in inductive motors. The inverter’s output stage uses multiple banks
of metal-oxide semiconductor field-effect transistors (MOSFETS). This stage functions
as a high-power bipolar switch, alternately applying opposite polarity to the AC out-
let HOT and NEUTRAL terminals.
Figure 4
Simplified Diagram
Some Models only include volt, Amp and over temp indicators.
The 110/120VAC output of the inverter is in the form of a modified sine wave
(MSW) as shown in
FIGURE 5
. This type of waveform has the same energy char-
acteristics as the sine wave of commercial electrical power. The modified sine
wave is superior to the 100% square wave output (not shown) produced by
most other DC-to-AC inverters on the market. A modified sine wave, as com-
pared to a square wave, is vital to the efficient and proper operation of certain
appliances such as computers, TVs, and certain electronic equipment.
Figure 5– Modified Square Wave and Sine Wave Comparison
8
See Specs for
Wire Gauge
and Fuse
Amperage
Page 18
