Application and Operation
6.1 Signal Frame of Reference for Motor Control
Product User Manual
106 Operating Instructions, Version AE 12/2009, A5E01454341C
6.1 Signal Frame of Reference for Motor Control
The control signals used for controlling the motor must be assigned a polarity for use over
four quadrants of control to maintain consistency of the algorithms. This section clarifies
what they are and what their polarities mean in the various quadrants.
6.1.1 Frame of Reference
The four-quadrant frame of reference is defined as the four quadrants of operation of a
motor. They are divided left to right by the direction of rotation and from top to bottom by the
polarity of the torque in the machine. Energy flow from the drive into the machine is called
motoring. Energy flow out of the machine and into the drive is called regeneration or braking.
Figure "Four Quadrant Operation of a Motor" shows the relationship between the polarities of
the signals. For example, starting at rest (in the ordinances of the two axes), if a positive
torque is applied to the motor, the acceleration is positive and the resultant speed increases
in the forward direction. This is governed by the following equations:
30RWRULQJ
3%UDNLQJ 0RWRULQJ3
)RUZDUG
5HYHUVH
VOLS
VOLS
%UDNLQJ3
˞˞
˞˞
7
7
˶˶
9
9
,,,
,9,,,
Figure 6-1 Four Quadrant Operation of a Motor
This then carries over into quadrant IV, showing that a negative torque produces negative
acceleration (deceleration), stopping the motor. If, however, the same torque is applied
continuously, the speed of the motor will decrease to zero and begin to accelerate in the
opposite direction producing a negative rotational speed (ω) in what is now quadrant III. Now
if a positive torque is applied, the motor enters quadrant II and begins to decelerate. Since
the rotational speed is negative, and begins to diminish and approach a positive value, the
acceleration must be positive to conform to the above equations. Again, if the torque is held
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