We can see from figure 8 that the output voltage in the
steady state has for half load is higher than full load.
Figure 9 shows the schematic circuit for the PWM
inverter with filtering implementation. At the input part,
Analogue Behavioral Modeling (ABM) is used instead of the
comparator because of ABM can handle higher frequency
range rather than comparator. The PWM inverter includes
PWM and a full bridge inverter. PWM is produced by
having a sinusoidal source as the modulating waveform and
a voltage pulse source as the carrier waveform. These two
waveforms are compared using an ABM model as said
earlier which will then produce PWM pulses. These pulses
will be sent to the four IGBTs (inverter) as their switching
signal. The switching scheme that used in this design is
bipolar type. The characteristic of the switching signal will
produce a sinusoidal waveform at the output of the inverter.
This signal is then filtered by a LC filter to produce a pure ac
waveform. The design of the filter is based on the location of
the first harmonic that exists at the output of the inverter.
In order to obtain a 240Vrms at the output, in an ABM