DickDV
Member
I'm popping in here kind of late but first I need to clarify that the ACS550 is not a DTC drive so all this about variably pulse rates doesn't apply. The 550 is simply a generic type of sensorless vector control and does not have excellent motor shaft control at and near zero speed just like any other sensorless vector system.
On the other hand, the ACS600 and now the 800 and 850 are DTC drives. You can expect them to develop full nameplate torque at zero speed.
In web applications, I would be very hesitant about using the ACS550. The ACS800 is much preferred. However, as kamenges has found, the 550 can do a very good job if an encoder is the speed feedback device. With an encoder I would expect zero speed control to be quite good.
And, just a note for kamenges, the tension control you describe IS a braking application except it doesn't involve stopping. All quadrant 2 and 4 operation is braking or, the motor developing torque in the opposite direction from the rotation.
Glad you got it solved. These are nice drives within their limitations, of course. If you are going to do much braking, you will not be able to depend upon flux braking alone. Flux braking is constant kw braking so at higher speeds there is very little braking torque. As you slow down, the braking torque increases noticeably. I would think that you would want to use the built-in brake chopper and add a braking resistor for web tensioning apps like yours.
Sorry I wasn't available earlier but I spent my whole day nursing an old 250hp DC motor back into operation on a hydraulic pump test cell with 40% field-weakened overspeed. And it was a Bardac 4Q drive which I am starting to like.
On the other hand, the ACS600 and now the 800 and 850 are DTC drives. You can expect them to develop full nameplate torque at zero speed.
In web applications, I would be very hesitant about using the ACS550. The ACS800 is much preferred. However, as kamenges has found, the 550 can do a very good job if an encoder is the speed feedback device. With an encoder I would expect zero speed control to be quite good.
And, just a note for kamenges, the tension control you describe IS a braking application except it doesn't involve stopping. All quadrant 2 and 4 operation is braking or, the motor developing torque in the opposite direction from the rotation.
Glad you got it solved. These are nice drives within their limitations, of course. If you are going to do much braking, you will not be able to depend upon flux braking alone. Flux braking is constant kw braking so at higher speeds there is very little braking torque. As you slow down, the braking torque increases noticeably. I would think that you would want to use the built-in brake chopper and add a braking resistor for web tensioning apps like yours.
Sorry I wasn't available earlier but I spent my whole day nursing an old 250hp DC motor back into operation on a hydraulic pump test cell with 40% field-weakened overspeed. And it was a Bardac 4Q drive which I am starting to like.
