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Unidrive M702 User Guide
Issue Number: 3
8 Optimization
This chapter takes the user through methods of optimizing the drive set-up and maximize the performance. The auto-tuning features of the drive
simplify the optimization tasks.
8.1 Motor map parameters
8.1.1 Open loop motor control
Pr 00.046 {05.007}
Rated Current
Defines the maximum continuous motor current
•
The rated current parameter must be set to the maximum continuous current of the motor. (See section 8.2
page 127, for information about setting this parameter higher than the maximum Heavy Duty current rating). The motor rated current is used in
the following:
•
Current limits (see section section 8.3
on page 127, for more information)
•
Motor thermal overload protection (see section section 8.4
on page 127, for more information)
•
Vector mode voltage control (see
Open Loop Control Mode
(00.007), later in this table)
•
Slip compensation (see
Enable Slip Compensation
(05.027), later in this table)
•
Dynamic V/F control
Pr 00.044 {05.009}
Rated Voltage
Defines the voltage applied to the motor at rated frequency
Pr 00.047 {05.006}
Rated Frequency
Defines the frequency at which rated voltage is applied
The
Rated Voltage
(00.044) and the
Rated Frequency
(00.047) are used
to define the voltage to frequency characteristic applied to the motor (see
Open Loop Control Mode
(00.007), later in this table). The
Rated
Frequency
(00.047) is also used in conjunction with the motor rated
speed to calculate the rated slip for slip compensation (see
Rated Speed
(00.045), later in this table).
Pr 00.045 {05.008}
Rated Speed
Defines the full load rated speed of the motor
Pr 00.042 {05.011}
Number Of Motor Poles
Defines the number of motor poles
The motor rated speed and the number of poles are used with the motor rated frequency to calculate the rated slip of induction machines in Hz.
Rated slip (Hz) = Motor rated frequency - (Number of pole pairs x [Motor rated speed / 60]) =
If Pr
00.045
is set to 0 or to synchronous speed, slip compensation is disabled. If slip compensation is required this parameter should be set to the
nameplate value, 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.
Pr
00.042
is also used in the calculation of the motor speed display by the drive for a given output frequency. When Pr
00.042
is set to ‘Automatic’,
the number of motor poles is automatically calculated from the rated frequency Pr
00.047
, and the motor rated speed Pr
00.045
.
Number of poles = 120 x (
Rated Frequency
(00.047) /
Rated Speed
(00.045)) rounded to the nearest even number.
Pr 00.043 {05.010}
Rated Power Factor
Defines the angle between the motor voltage and current
The power factor is the true power factor of the motor, i.e. the angle between the motor voltage and current. The power factor is used in conjunction
with the
Rated Current
(00.046), 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 stator resistance compensation. It is important that this
parameter is set up correctly. The drive can measure the motor rated power factor by performing a rotating autotune (see Autotune (Pr 00.040),
below).
Output
voltage
Pr
/ 2
00.044
Pr
00.044
Pr
/
2
00.047
Pr
00.047
Output
frequency
Output voltage characteristic
00.047
00.042
2
------------------
00.045
60
------------------
×
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Summary of Contents for Unidrive M702
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