Chapter 1: PREFACE AND GENERAL
Page 6 of 28
Operating manual DC6AT
Accordingly, one-quadrant (1Q) devices can operate a motor in one direction, whereby the
motor outputs power to its shaft; i.e., it drives the machine. 1Q devices can also be used for
a reversal of direction. In this case, the motor operates in Quadrant 3. The term 1Q device is
still used, to avoid confusion.
Two-quadrant (2Q) devices can drive a motor forward (Quadrant 1), and can perform con-
trolled braking of the motor in forward direction (Quadrant 2).
Four-quadrant (4Q) devices can drive a motor in both directions of rotation (Quadrants 1 and
3) and perform controlled braking in both directions (Quadrants 2 and 4).
1.2.2 Control operation in drive controllers for DC-motors
ANTEK DC6AT series drive controllers hold the torque constant within very close tolerances
without having to resort to a speed feed-back (tacho). The operating principle is based on a
speed controller with underlying current controller.
Speed
controller with
IxR-
compensation
Current controller
Motor current
=M
Set value
With the underlying current controller the motor is operated with continuous current, which
results in nearly constant torque. Load changes on the motor shaft are reflected therefore in
speed changes that are recognised by the speed controller as lower terminal voltage on the
motor and directly controlled. The advantage of this constellation is that the control variable
of the speed controller acts on the set value of the current controller and the motor is thus
returned with high torque from standard deviations to solid speed.
1.2.3 IxR – Compensation
With an ideal DC-motor without loss the motor voltage would be proportional to the speed.
The following equivalent circuit diagram shows that the terminal voltage is equal to the EMF
1
.
I
deal motor
=M
U
kl
EMF
L
Mot