Instead
of
a
mechanical
gearbox
and
double-fed
induction
generator
(DFIG)
combination
or
an
integrated
direct-drive
transmission,
it
uses
a
low-speed
hydraulic
pump
connected
to
a
high-speed
hydraulic
motor
with
a
closed-loop
circuit
powering
a
synchronous
generator
without
the
need
for
frequency
converter.
In
conventional
DFIG
or
direct-drive
systems,
the
speed
of
the
rotor
is
controlled
by
the
frequency
converter
and
transformer.
ChapDrive’s
design,
by
contrast,
controls
rotor
speed
“up
front”
with
the
hydraulic
pump
and
motor,
in
front
of
the
generator,
using
computer-controlled
valves
that
switch
to
pump,
motor
or
idle
mode…
