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122 Unidrive SPM User Guide
www.controltechniques.com Issue Number: 3
The power factor is the true power factor of the motor, i.e. the angle
between the motor voltage and current.
Open-loop
The power factor is used in conjunction with the motor rated current
(Pr 0.46) to calculate the rated active current and magnetising current of
the motor. The rated active current is used extensively to control the
drive, and the magnetising current is used in vector mode Rs
compensation. It is important that this parameter is set up correctly.
This parameter is obtained by the drive during a rotational autotune. If a
stationary autotune is carried out, then the nameplate value should be
entered in Pr 0.43.
Closed-loop vector
If the stator inductance (Pr 5.25) contains a non-zero value, the power
factor used by the drive is continuously calculated and used in the vector
control algorithms (this will not update Pr 0.43).
If the stator inductance is set to zero (Pr 5.25) then the power factor
written in Pr 0.43 is used in conjunction with the motor rated current and
other motor parameters to calculate the rated active and magnetising
currents which are used in the vector control algorithm.
This parameter is obtained by the drive during a rotational autotune. If a
stationary autotune is carried out, then the nameplate value should be
entered in Pr 0.43.
The phase angle between the rotor flux in a servo motor and the
encoder position is required for the motor to operate correctly. If the
phase angle is known it can be set in this parameter by the user.
Alternatively the drive can automatically measure the phase angle by
performing a phasing test (see autotune in servo mode Pr 0.40). When
the test is complete the new value is written to this parameter. The
encoder phase angle can be modified at any time and becomes effective
immediately. This parameter has a factory default value of 0.0, but is not
affected when defaults are loaded by the user.
Open-loop & Closed-loop vector
Enter the value from the rating plate of the motor.
Open-loop
This is the speed at which the motor would rotate when supplied with its
base frequency at rated voltage, under rated load conditions (=
synchronous speed - slip speed). Entering the correct value into this
parameter allows the drive to increase the output frequency as a
function of load in order to compensate for this speed drop.
Slip compensation is disabled if Pr 0.45 is set to 0 or to synchronous
speed, or if Pr 5.27 is set to 0.
If slip compensation is required this parameter should be set to the value
from the rating plate of the motor, which should give the correct rpm for a
hot machine. Sometimes it will be necessary to adjust this when the
drive is commissioned because the nameplate value may be inaccurate.
Slip compensation will operate correctly both below base speed and
within the field weakening region. Slip compensation is normally used to
correct for the motor speed to prevent speed variation with load. The
rated load rpm can be set higher than synchronous speed to deliberately
introduce speed droop. This can be useful to aid load sharing with
mechanically coupled motors.
Closed loop vector
Rated load rpm is used with motor rated frequency to determine the full
load slip of the motor which is used by the vector control algorithm.
Incorrect setting of this parameter can result in the following:
• Reduced efficiency of motor operation
• Reduction of maximum torque available from the motor
• Failure to reach maximum speed
• Over-current trips
• Reduced transient performance
• Inaccurate control of absolute torque in torque control modes
The nameplate value is normally the value for a hot machine, however,
some adjustment may be required when the drive is commissioned if the
nameplate value is inaccurate.
The rated full load rpm can be optimised by the drive (For further
information, refer to section 10.1.3 Closed loop vector motor control on
page 141).
Servo
Pr 0.45 is the motor thermal time constant of the motor, and is used
(along with the motor rated current Pr 0.46, and total motor current
Pr 0.12) in the thermal model of the motor in applying thermal protection
to the motor.
Setting this parameter to 0 disables the motor thermal protection.
For further details, refer to section 10.4 Motor thermal protection on
page 146.
Enter the name-plate value for the motor rated current.
Open-loop & Closed-loop vector
Enter the value from the rating plate of the motor.
0.43 {5.10} Motor rated power factor
RW Uni US
OL
Ú
0.000 to 1.000
Ö
0.850
VT
ÚÖ
0.43 {3.25} Encoder phase angle
RW Uni US
SV
Ú
0.0 to 359.9°
Ö
0.0
0.44 {5.09} Motor rated voltage
RW Uni RA US
Ú
0 to
AC_VOLTAGE_SET_MAX V
Ö
200V drive: 230
400V drive: EUR> 400
USA> 460
575V drive: 575
690V drive: 690
0.45 {5.08} Motor rated full load speed (rpm)
RW Uni US
OL
Ú
0 to 180,000 rpm
Ö
EUR> 1,500
USA> 1,800
VT
Ú
0.00 to 40,000.00 rpm
Ö
EUR> 1,450.00
USA> 1,770.00
0.45 {4.15} Motor thermal time constant
RW Uni US
SV
Ú
0 to 3000.0
Ö
20.0
0.46 {5.07} Motor rated current
RW Uni RA US
Ú
0 to Rated_current_max A
Ö
Drive rated current [11.32]
0.47 {5.06} Rated frequency
RW Uni US
OL
Ú
0 to 3,000.0Hz
Ö
EUR> 50.0, USA> 60.0
VT
Ú
0 to 1,250.0Hz
Ö
EUR> 50.0, USA> 60.0
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