Answer Posted / thowsif_csm team_emerson
DC Drives:-
Commonly a DC drive is a device that uses AC as
poer source to power and control a DC motor. The cheap
definition... The drive has two parts the power components
and a controler. The power components convert AC power to
DC by a Rectifier. The controller (among other things) is
basicly a high speed timer that fires a solid state device
(BPT, IGBT or some other gate) very rapidly (Pulse width
modulation on and off). The controller gets a setpoint from
a potentiometer or some other means perhaps a digital
number via some protocol and uses a means of maintaing this
setpoint by calculating the difference between the setpoint
and the actual speed with a tach or some other means and
adjust the output accordingly.
AC Drive:-
AC drives are also known as adjustable-
frequency drives (AFD), variable-speed drives (VSD),
Variable-frequency drives, microdrives or inverter drives.
Since the voltage is varied along with frequency, these are
sometimes also called VVVF (variable voltage variable
frequency) drives.
A AC drive is a system for controlling the rotational speed
of an alternating current (AC) electric motor by
controlling the frequency of the electrical power supplied
to the motor A variable frequency drive is a specific type
of adjustable-speed drive.
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