low speed current limit

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User15043
Level 1
Level 1
5 replies posted First question asked First reply posted
Hi,
I am using MCEWizard to config my IMM101T kit. I see the question about the low speed current limit and low speed threshold. Anyone tell me what exactly it is and how to determine them? Do they depend on the
mathematic model of the motor or the load characteristics.

In addition, the start-up algorithm that iMOTION 2.0 use is V/f, isn't it?
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2 Replies
User19695
Level 1
Level 1
10 replies posted 5 replies posted First question asked
hi,
Have you solved your problem?
We are also using MCE to complete some project, the explanation of the parameters is not clear, and Infineon-MCESW-RM-UserManual-v01_03-EN.pdf the documentation is not very detailed.
We look forward to infineon reply.

Thanks!
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Casey
Employee
Employee
50 replies posted 25 replies posted 10 replies posted
Hello,
These two parameters are end application dependent and allow the user to set a lower current limit during starting. This limit setting is used for the parking current and for the open loop current ramp, and when running.

The value settings depends on the motor load characteristics.
• If you are running a compressor and need maximum acceleration at startup then set the low speed limit to 100%.
• If you are running a fan and do not need a high acceleration at startup then set a low value for the “low speed limit” and set the low speed threshold at a speed value where you will need to use the full current limit.
* If you know the motor torque constant and total shaft inertia (motor + load inertia) you can use the low speed limit from this equation: T_m = KT_m * I_start = J_m+load * acc_start (all in SI units)
* In open loop starting, the open loop ramp acceleration should be 10—20% lower than acc_start (converted from SI units)

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