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Menu 4
Unidrive SP Advanced User Guide 97
Issue Number: 10 www.controltechniques.com
This parameter is the r.m.s. current from each output phase of the drive. The phase currents consist of an active component and a reactive
component. The three phase currents can be combined to form a resultant current vector as shown below:
The resultant current magnitude is displayed by this parameter. The active current is the torque producing current for a motor drive and the real
current for a regen unit. The reactive current is the magnetizing or flux producing current for a motor drive.
Open-loop, Closed-loop vector and Servo
The active current is the torque producing current in a motor drive.
The active current is aligned with the y axis of the reference frame. In open-loop mode the x axis of the reference frame is aligned with the stator flux
vector. In Closed-loop vector and Servo modes the x axis of the reference frame is aligned with the rotor flux vector. The motor torque is proportional
to the torque producing current when field weakening is not active. Once field weakening is active the torque producing current is boosted to
compensate for the reduction in motor flux.
Regen
The active current is the real current in a regen unit.
The active current is aligned with the y axis of the reference frame. The y axis of the reference frame is aligned with the regen unit terminal voltage
vector.
4.01 Current magnitude
Drive modes Open-loop, Closed-loop vector, Servo, Regen
Coding
Bit SP FI DE Txt VM DP ND RA NC NV PT US RW BU PS
1 121 1 1 1
Range
Open-loop, Closed-loop vector, Servo,
Regen
0 to DRIVE_CURRENT_MAX A
Update rate 4ms write
4.02 Active current
Drive modes Open-loop, Closed-loop vector, Servo, Regen
Coding
Bit SP FI DE Txt VM DP ND RA NC NV PT US RW BU PS
1 121 1 1
Range
Open-loop, Closed-loop vector, Servo,
Regen
±DRIVE_CURRENT_MAX A
Update rate 4ms write
Direction of active current Direction of rotation Torque direction
+ + Forward (accelerating)
- + Reverse (decelerating)
+ - Forward (decelerating)
- - Reverse (accelerating)
Direction of active current Power flow
+ From supply
- Into supply
Pr
4.02
Resultant
output current
Pr
4.01
Pr
4.17
y
x
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