Setup
Start-up Procedure
ESCON Module 50/4 EC-S Hardware Reference
3-14
CCMC | 2021-08 | rel9026
3.2
Start-up Procedure
A successful sensorless start-up procedure consists of two phases; the alignment phase and the accelera-
tion phase.
ALIGNMENT PHASE
The motor shaft will be brought to and stabilized in a defined rotor position. This will be accomplished by
applying a motor current ramp with a fixed step configuration without rotating stator field. During the align-
ment phase the motor current I
start
rises.
ACCELERATION PHASE
A synchronous rotation of the motor with a constant acceleration
α
is being forced until the speed is suffi-
ciently high for Back-EMF sampling. The motor current is limited to I
start
.
Note
Under unfavorable conditions, the sensorless commutation principle can lead to start-up problems.
Thereby, the following aspects can have a negative effect on the reliable start-up:
• high friction torques
• high moment of inertia in combination with low friction
• unsuitably defined start-up parameter
CAUTION
Risk of injury
During the starting operation, the motor shaft will temporarily move in both directions
• Do not take the device into operation unless all protective devices on moving parts have been com-
pletely attached and checked for proper function.
• Make sure that no loose objects are in the vicinity of any moving parts. Keep any objects which could
get caught away.
