Principle Of Operation - Samplex Power SAM-100-12 Manuel Du Propriétaire

SECTION 2 |
Cooling Fan
A fan has been provided for cooling (5, Fig. 3.1). It runs all the time.

PRINCIPLE OF OPERATION

Conversion of 12 VDC from the battery / other DC source to 115 VAC takes place in 2
stages. In the first stage, the 12 VDC is converted to high voltage DC (around 160 VDC)
using high frequency switching and Pulse Width Modulation (PWM) technique. In the
2nd stage, the 160V high voltage DC is converted to 115V, 60 Hz Modified Sine Wave
AC. (Note: 115 V is the RMS value of the Modified Sine Wave AC voltage. The peak
value of the Modified Sine Wave AC voltage will be equal to the value of the above
high voltage of around 160V. See the Fig 2.1 below).
Modified Sine Waveform -
Charateristics & Comparison with Pure Sine Waveform
Please refer to Fig 2.1 below which shows one cycle of Modified Sine Wave and Pure
Sine Wave for comparison.
180
160
140
120
100
V +
80
60
40
20
0
20
40
60
V -
80
100
120
140
160
180
Fig 2.1 Modified Sine Wave and Pure Sine Wave - Comparison
The output waveform of the inverter is a Modified Sine Wave. In a Modified Sine Wave,
the voltage waveform consists of rectangular pulses that approximate sine wave pulses
of a Pure Sine Wave. The voltage rises and falls abruptly at a particular phase angle
and sits at 0 Volts for some time before changing its polarity. In a Pure Sine Wave, the
voltage rises and falls smoothly with respect to phase angle and the voltage changes its
polarity instantly when it crosses 0 Volts.
6 | SAMLEX AMERICA INC.
Introduction
Pure Sine Wave
crosses 0V
instantaneously
TIME
Modified Sine
115 RMS
Wave sits at
0V for some
time and then
rises or falls
Legend
Modified Sine Wave
Sine Wave