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Menu 5

Unidrive SP Advanced User Guide 113

Issue Number: 10 www.controltechniques.com

Open-loop

Although the range for scaling purposes is ±SPEED_FREQ_MAX, the actual parameter value can be increased beyond this range by slip

compensation. This parameter gives the output frequency of the drive, i.e. the sum of the post ramp reference and the slip compensation.

Closed-loop vector and Servo

In these modes the output frequency is not controlled directly, and so the output frequency displayed in this parameter is calculated by measuring the

frequency of the controller reference frame.

Regen

In Regen mode the supply frequency is shown. Negative values indicate negative phase rotation of the supply.

This is the modulus of the r.m.s. line to line voltage at the inverter output at the drive output frequency.

Open-loop, Closed-loop vector and Servo modes

The output power is the dot product of the output voltage and current vectors. Positive power indicates power flowing from the drive to the motor

(motoring) and negative power indicates power flowing from the motor to the drive (regen).

Regen mode

The output power is the dot product of the output voltage and current vectors. Positive power indicates power flowing from the supply to the drive, and

negative power indicates power flowing from the drive to the supply.

The motor rpm is calculated from the post ramp reference (Pr 2.01) for normal operation, or the slave frequency demand (Pr 3.01) if frequency slaving

is being used. The speed of rotation is calculated as follows:

rpm = 60 x frequency / no. of pole pairs

This calculation relies on the number of motor poles being set up correctly in Pr 5.11, or if auto mode is selected (Pr 5.11 = 0) then it relies on a

reasonably accurate value of motor rated speed being set in Pr 5.08 to allow correct calculation of the motor poles. If frequency slaving is being used

there will be an error due to the slip frequency. However, in normal operation the result will be reasonably accurate provided that the slip

compensation has been set up correctly in the rated full load rpm parameter (Pr 5.08).

5.01 Output frequency

Drive modes Open-loop, Closed-loop vector

Coding