
Power
Electronic Converters for Motor Drives
63
3-phase inverter
A 3-phase output can be obtained
by
adding only two more
switches to the four needed for
a
single-phase inverter, giving
the typical power-circuit configuration shown
in
Figure 2.15.
-L
D.C
lit
Link
it
IT
it
—o
—————o
—o
—————o
3-phase
Output
Figure
2.15 Three-phase inverter power circuit
ics,
since these are the ones which the motor is most likely
to
respond to.
The number, width, and spacing
of
the pulses
is
therefore
optimized to keep the harmonic content as low as possible.
A
host
of
sophisticated strategies have been developed, almost
all using
a
microprocessor based syste ...