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SIMILAR PRODUCTS
SGMAH-02AAA61D-OY
SGMAH-02AAA61D-YO
SGMAH-02AAA6C
SGMAH-02AAA6CD-0Y
SGMAH-02AAA6SD
SGMAH-02AAAG761
SGMAH-02AAAGB61
SGMAH-02AAAH161
SGMAH-02AAAH76B
SGMAH-02AAAHB61
SGMAH-02AAAJ32C
SGMAH-02AAAJ361
SGMAH-02AAA-SB12
SGMAH-02AAAYU21
SGMAH-02AAF4C
SGMAH-02ABA21
SGMAH-02ACA-SW11
SGMAH-02B1A21
SGMAH-02B1A2C
SGMAH-02B1A41
SGMAH-02B1A6C
SGMAH-02BAA21
SGMAH-02BAA41
SGMAH-02BAAG721
SGMAH-02BBA21
SGMAH-03BBA-TH11
SGMAH-04A1A2
SGMAH-04A1A21
SGMAH-04A1A2B
SGMAH-04A1A2C
SGMAH-04A1A41
SGMAH-04A1A4B
SGMAH-04A1A4C
As A' approaches 1 on the Bode diagram (at 10 rad/sec. in the
example), the denominator becomes 1 + 1∠- 180° = 1-1 = 0 and F/C
becomes infinite! This will result in severe oscillations. In order
to maintain a stable system, the denominator must not be allowed to
approach 0. When the term "phase margin" is used, it expresses how
close the phase shift of A' is to -180° when A' = 1 in magnitude. A
commonly accepted design goal is for A' to have -135° of phase
shift or less (45° of phase margin). This will result in a 25
percent overshoot of the closed loop system in response to small
step inputs in position as shown below.
When to Use a Stepper Motor
A stepper motor can be a good choice whenever controlled movement
is required. They can be used to advantage in applications where
you need to control rotation angle, speed, position and
synchronism. Because of the inherent advantages listed previously,
stepper motors have found their place in many different
applications. Some of these include printers, plotters, highend
office equipment, hard disk
drives, medical equipment, fax machines, automotive and many more.
The Rotating Magnetic Field
When a phase winding of a stepper motor is energized with current a
magnetic flux is developed in the
stator. The direction of this flux is determined by the “Right Hand
Rule” which states: “If the coil is grasped in the right hand with
the fingers pointing in the direction of the current in the winding
(the thumb is extended at a 90° angle to the fingers), then the
thumb will point in the direction of the magnetic field.”
Figure 5 shows the magnetic flux path developed when phase B is
energized with winding current in the
direction shown. The rotor then aligns itself so that the flux
opposition is minimized. In this case the motor
would rotate clockwise so that its south pole aligns with the north
pole of the stator B at position 2 and its
north pole aligns with the south pole of stator B at position 6. To
get the motor to rotate we can now see that
we must provide a sequence of energizing the stator windings in
such a fashion that provides a rotating
magnetic flux field which the rotor follows due to magnetic
attraction.
The magnetic field generated in the stator induces an EMF in the
rotor bars. In turn, a current is produced in the rotor bars and
shorting ring and another magnetic field is induced in the rotor
with an opposite polarity of that in the stator. The magnetic
field, revolving in the stator, will then produces the torque which
will “pull” on the field in the rotor and establish rotor rotation.
In the design of the induction motor, operational characteristics
can be determined through a series of calculations. Performing
these calculations can help the engineer provide a motor that is
best suited to a particular application. This paper will
demonstrate their application.
