Lenze i700 - Manual (Page 136)

5 Motor control & motor settings
5.14 Parameterising the V/f characteristic control
136
Lenze · i700 servo inverter · Reference manual · DMS 1.5 EN · 03/2014 · TD05
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5.14 Parameterising the V/f characteristic control
In case of the V/f characteristic control (VFCplus), the motor voltage of the inverter is determined by
means of a linear or quadratic characteristic depending on the field frequency or motor speed to be
generated. The voltage follows a preselected characteristic.
Initial commissioning steps
After the motor and controller have been optimally adjusted to each other, the following "initial
commissioning steps" are sufficient for a simple V/f characteristic control.
1. Defining the V/f characteristic shape
2. Activating the voltage vector control (lmin controller)
– or alternatively –
Setting the voltage boost
3. Setting the load adjustment
4. Defining the behaviour at the current limit (Imax controller)
Optimising the control mode
The following "optimisation steps" can be used to further optimise the control mode of the V/f
characteristic control and adapt it to the practical application:
1. Setting the slip compensation
2. Setting the oscillation damping
3. Manual test mode "Current pulse"
• Only required if the voltage vector control is applied, or if DC-injection braking or the flying
restart process is activated.

Stop!
• The V/f characteristic control is only suitable for asynchronous motors.
• Observe the following when you actuate drives with a square-law V/f characteristic:
• Please always check whether the corresponding drive is suitable for operation with
a quadratic V/f characteristic!
• If your pump drive or fan drive is not suitable for operation with a square-law V/f
characteristic, use the linear V/f characteristic instead, or select the servo control.
• For adjustment, observe the thermal performance of the connected asynchronous
motor at low output frequencies.
• Usually, standard asynchronous motors with insulation class B can be operated for
a short time with their rated current in the frequency range 0 Hz ... 25 Hz.
• Contact the motor manufacturer to get the exact setting values for the max.
permissible motor current of self-ventilated motors in the lower speed range.
• For square-law V/f characteristics we recommend setting a smaller V
min
.
• As regards the motor nameplate data, at least the rated speed ( 0x2C01:4 or 0x3401:4
for axis B) and the rated frequency ( 0x2C01:5 or 0x3401:5 for axis B) must be entered
for the i700 servo inverter to calculate the correct number of pole pairs.