Introduction to Electrical Power and Power Electronics

375AC–DC–AC Converters

Another important denition in the PWM switching is the following:

amplitude modualtionratio

a

peak-reference

M

V

V

=

ppeak-carrier

peak-sinecontrol

peak-triangular

=

V

V

. (14.33)

If M

a

< 1, the peak amplitude of the fundamental frequency output voltage V

1

is

linearly proportional to M

a

, that is,

V

1peak

= M

a

∙ V

dc

and V

1rms

= M

a

V

dc

/√2. (14.34)

Thus, V

1

is linearly controlled by M

a

. Such control is used for varying V

1

under

xed V

dc

or holds the output V

1

constant under uctuating V

dc

.

If M

a

> 1, V

1

increases with M

a

, but not linearly, and remains between V

d

and

4V

dc

/π.

If the inverter output load with some inductance draws a sinusoidal ...