Samlexpower PST-100S-12E Owner's Manual - Section 5 |
14 | SAMLEX AMERICA INC.
seCtIOn 5 |
Principle of Operation
TheseinvertersconvertDCbatteryvoltagetoACvoltagewithanRMS(RootMean
Square)valueof230VAC,50HzRMS.
ThewaveformoftheACvoltageisapuresinewaveformthatissameasthewaveform
of grid power (Supplementary information on pure sine waveform and its advantages
are discussed on pages 8 & 9).
fig.5.1belowspecifiesthecharacteristicsof230VAC,50Hzpuresinewaveform.The
instantaneous value and polarity of the voltage varies cyclically with respect to time. for
example,inonecycleina230VAC,50Hzsystem,itslowlyrisesinthepositivedirection
from0Vtoapeakpositivevalue“Vpeak”=+325V,slowlydropsto0V,changesthe
polaritytonegativedirectionandslowlyincreasesinthenegativedirectiontoapeak
negativevalue“Vpeak”=-325Vandthenslowlydropsbackto0V.Thereare50such
cyclesin1sec.Cyclespersecondiscalledthe“frequency”andisalsotermed“Hertz
(Hz)”.
Fig. 5.1: 230 VAC, 50 Hz Pure Sine Waveform
Thevoltageconversiontakesplaceintwostages.Inthefirststage,theDCvoltage
ofthebatteryisconvertedtoahighvoltageDCusinghighfrequencyswitchingand
PulseWidthModulation(PWM)technique.Inthesecondstage,thehighvoltageDCis
convertedto230VAC,50HzsinewaveACagainusingPWMtechnique.Thisisdoneby
usingaspecialwaveshapingtechniquewherethehighvoltageDCisswitchedatahigh
frequency and the pulse width of this switching is modulated with respect to a refer-
ence sine wave.
TIME
OV
+
-
-V
PEAK
= -325V
+V
PEAK
= + 325V
V
RMS
= 230 VAC