Lenze 8400 motec - Manual (Page 136)

5 Motor control (MCTRL)
5.9 Sensorless control for synchronous motors (SLPSM)
136 Lenze · 8400 motec · Reference manual · DMS 4.1 EN · 08/2013 · TD05
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Speed controller gain Vp
The gain Vp (
C00070/3 ) of the speed controller is defined in a scaled representation which enables
a comparable parameterisation almost independent of the power of the motor or inverter. Here, the
speed input difference of the controller is scaled to the rated motor speed whereas the output
torque refers to the rated motor torque. A gain of 10 means that a speed difference of 1 % is gained
through the P component with 10 % torque.
If the rated data of the motor and the mass inertia of the drive system are known, we recommend
the following setting:
[5-6] Recommendation for the setting of the gain of the speed controller
If the mass inertia of the drive is unknown, the optimisation can be achieved as follows:
1. Specify speed setpoint.
• A small speed just above the switching threshold is recommended in the closed-loop
controlled operation.
2. Increase Vp ( C00070/3 ) until the drive starts to oscillate (observe engine noise).
3. Reduce Vp ( C00070/3 ) until the drive runs stable again.
4. Reduce Vp ( C00070/3 ) to approx. half the value.
5. Afterwards check results of the optimisation in the entire speed range (one-time passing
through of the speed range).

Tip!
Values recommended by Lenze for the setting of the (proportional) gain:
• For drive systems without feedback: Vp = 2 … 8
• For drive systems with a good disturbance behaviour: Vp > 6
V
P
= Gain of the speed controller ( C00070/3 )
T
M
= Time constant for the acceleration of the motor
M
N
= Rated motor torque
n
N
= Rated motor speed
J
drive, total
= Total moment of inertia of the drive
V
P
0.2 ... 0.5
T
M
s [ ]
0.01 s [ ]
------------------- ⋅ ≈
T
M
s [ ]
2 π n
N
rpm [ ] ⋅ ⋅
M
N
Nm [ ] 60 ⋅
-------------------------------------- J
Drive, total
kgm
2
[ ] ⋅ =
M
N
Nm [ ]
P
N
W [ ] 60 ⋅
2 π n
N
rpm [ ] ⋅ ⋅
-------------------------------------- =