AN1910 Freescale Semiconductor / Motorola, AN1910 Datasheet - Page 3

• Manufacturer Part Number: AN1910
• Description: 3-Phase AC Motor Control with V/Hz Speed Closed Loop Using the DSP56F80X
• Manufacturer: Freescale Semiconductor / Motorola

3.
3.1 3-phase AC Induction Motor Drives
The PWM outputs are configured in the complementary mode in this application.
The AC induction motor is a workhorse with adjustable speed drive systems. The most popular type is
the 3-phase, squirrel-cage AC induction motor. It is maintenance-free, lower noise and efficient motor.
The stator is supplied by a balanced 3-phase AC power source.
The synchronous speed n
where f
is produced by slip frequency. The motor speed is characterized by a slip s
where n
torque characteristics and corresponding slip. As can be seen from
speed is controlled by variation of a stator frequency with influence of the load torque.
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Target Motor Theory
s
r
Half-cycle reload capability
Integral reload rates from one to 16
Individual software-controlled PWM output
Programmable fault protection
Polarity control
20-mA current sink capability on PWM pins
Write-protectable registers
is the synchronous stator frequency in Hz, and p is the number of stator poles. The load torque
is the rotor mechanical speed and n
3-Phase AC Motor Control with V/Hz Speech Closed Loop
Freescale Semiconductor, Inc.
s
For More Information On This Product,
of the motor is given by
s
n
r
s
=
=
--------------------
120 f
------------------ -
n
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s
n
p
–
s
n
r
s
=
sl
n
----- -
n
sl
s
is the slip speed, both in rpm.
rpm
-
EQ 3-1
r
:
Figure 3-1
and
Target Motor Theory
EQ 3-2
(EQ 3-1.)
(EQ 3-2.)
illustrates the
the motor
3