User Manual V 1-4.XX User guide

9-2 Applications
How Do Encoderless and Encoder Feedback Modes
Differ?
The following table compares the encoderless mode to the encoder
feedback mode.
Improving Speed Regulation in Encoderless Mode
After completing the auto-tune tests, you can adjust Slip Gain
(parameter 169) to improve the speed regulation (as a function of
load) in encoderless mode. Slip Gain defaults to 100% and typically
results in ±0.5% speed regulation.
Ideally, you should adjust Slip Gain while the motor is fully loaded
and at its normal operating temperature. Adjust Slip Gain until the
actual speed, as measured by an independent source such as a hand
tachometer, is equal to the desired speed. This should result in a
minimum steady state speed deviation as load changes. The proper
slip for good speed regulation also depends on the motor temperature;
thus, if the motor operating temperature normally varies between cold
and hot, select a compromise slip gain.
Using the Motor Simulation Mode
You can use the motor simulation mode to simulate a system that does
not have a motor present. This can be useful for testing purposes.
Category Encoderless Mode Encoder Feedback Mode
Speed regulation requirements
Applicable when requirements are larger than
±0.5% of base speed. May be applicable for
requirements between ±0.1% and ±0.5% with
manual adjustments.
Recommended for requirements smaller than
0.1% of base speed.
Minimum speed
1,2
Applicable when the minimum speed is greater
than 1/60 of base speed (that is, 30 rpm on a 60
Hz, 4 pole motor). May be applicable down to
speeds of 1/120 of base speed (15 rpm) if high
bandwidth responses are not required.
Recommended for speeds less than 1/120 of
base speed (15 rpm).
Maximum operating speed
Depends on the number of motor poles. A
4 pole motor has a maximum operating speed of
7200 rpm.
Depends on the number of motor poles. A 4 pole
motor has a maximum operating speed of 7200
rpm.
Maximum speed bandwidths
3
30 radians/second 100 radians/second
Starting torque
4
150% of rated motor torque 150% of rated motor torque
Torque regulation ±5% ±2%
Start into spinning motor Some cogging may occur Smooth start
Speed range 120:1 1000:1
Output frequency range 0 – 250 Hz 0 – 250 Hz
1 Erratic operation, including cogging, may result at speeds less than 1/60 of base speed.
2 You can use Min Speed Limit (parameter 215) to adjust the minimum speed.
3 The maximum speed bandwidths are with no inertia connected to the motor. The maximum achievable bandwidths decrease with increasing
connected inertia for both sensorless and encoder modes.
4 The available starting torque is at least 150% motor torque and could be as higher than 300% if the inverter can supply the current. Refer to
Max Mtr Current (parameter 195).
file:
Motor/Inverter
group:
Motor Constants