Voltage Controller Gain; Motor Torque Per Amp (Kt) - Emerson unidrive sp User Manual

Parameter Keypad and
Menu 5
structure display
The drive can include the effects of saturation by representing the flux producing current to flux characteristic as a series of three lines as shown
below:
flux (%)
100%
Pr 5.30
Pr 5.29
50
If Pr 5.29 and Pr 5.30 have their default values of 50 and 75, the characteristic becomes one line and there will be a linear relationship between the
drive estimate of flux and the flux producing current. If Pr 5.29 and Pr 5.30 are increased above 50 and 75 the drive estimate of flux can include the
effect of saturation. It is unlikely that information will be available to set up these parameters, and so the values are determined during the rotating
auto-tune test.
5.31

Voltage controller gain

Drive modes Open-loop, Closed-loop vector, Servo
Bit SP
Coding
Range Open-loop, Closed-loop vector, Servo
Default Open-loop, Closed-loop vector, Servo
Update rate Background read
This parameter controls the gain of the voltage controller used for mains loss and standard ramp control. If the parameter is set to 1 the gain used is
suitable for applications where the drive is used alone. Higher values are intended for applications where the DC bus of each drive is connected in
parallel and the drive is used as a master for mains loss control. This is intended for use in applications where each drive is locked together using
open-loop frequency slaving. (If motors are locked together using digital-locking, using a master for mains loss control, it is unlikely that the system
will be stable during mains loss unless the power rating of the master is much higher than the combined rating of the slaves. This is due to the lag
created by the master motor inertia).
5.32

Motor torque per amp (Kt)

Drive modes Closed-loop vector, Servo
Coding Bit SP
CLV
SV
Range Closed-loop vector, Servo
Default Servo
Update rate Background (1s) read
This parameter shows the motor torque per amp of active (torque producing) current used to calculate the speed controller gains when the automatic
set-up methods are active (i.e. Pr 3.17 = 1 or 2).
Closed-loop vector
The drive calculates the motor torque per amp of active current using the motor parameters as shown below assuming a motor efficiency of 90%.
√3 x Vrated x Irated x Rated power factor x Efficiency
Kt =
-1
Rated speed (rad s
√3 x Pr 5.09 x Pr 5.07 x Pr 5.10 x 0.9
Kt =
(2π x Pr 5.08 / 60) x Rated active current
Rated active current is the active current when the motor current is equal to the rated motor current and is defined at the start of the description of
menu 4.
Servo
The motor torque per amp (Kt) must be entered in this parameter by the user for the automatic gain calculation system to operate correctly, and to
allow the drive to calculate the correct inertia during an inertia auto-tune.
130
Parameter Parameter
x.00 description format
75 100 i_mag (%)
FI DE Txt VM DP ND RA
0 to 30
1
FI DE TE VM DP ND RA NC NV
2 1
2
) x Rated active current
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Advanced parameter
Macros
descriptions
NC NV PT US RW BU
1
PT US RW BU
1
-1
0.00 to 500.00 NmA
1.60
Serial comms Electronic
protocol nameplate
PS
1 1
PS
1
1 1
Unidrive SP Advanced User Guide
Performance RFC mode
Issue Number: 10