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Motor Control ICs Forum Discussions

Vel
Level 1
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First reply posted First question asked Welcome!

Hi,

I have developed a controller board based on REF-Fridge_D111T (https://www.infineon.com/cms/en/product/evaluation-boards/ref_fridge_d111t_mos/).

The control mode I am using is current control mode.

When I start the motor in no load,  it ramps up too fast to high speed 16000RPM and gate kill is triggered.

How to slow down the ramp rate in current control mode?

For some reason, when I try to control the speed using Vsp analog input with current control mode, the motor starts and then immediately spins in opposite direction. what can cause this issue? 

 

Thanks 🙂

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1 Solution
Krupashankar
Moderator
Moderator
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250 replies posted 100 solutions authored 5 likes given

Hi @Vel,

In case of current control mode IqRef_Ext is the only way to control the speed. There is no ramp rate to control the speed in case of current control mode.

Krupashankar_0-1671437964427.png

IqRef_Ext can be varied based on the load using the custom script. For more details on script language please refer to : How to Use iMOTION™ Script Language 

Filed weakening can be controlled based on FwkVoltLvl. This parameter specifies the modulation threshold to start field weakening.  For more details refer to section 3.2.6.5 FwkVoltLvl of iMOTION™ Motion Control Engine
Software Reference Manual 

Please let us know if any further details are required.

 

Thanks,

Krupashankar

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Krupashankar
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250 replies posted 100 solutions authored 5 likes given

Hi @Vel,

Regarding gatekill fault please refer to this thread: Gate kill error in D111T 

In case of current control mode the ramp rate depends on rate at which IqRef_Ext is varied.

IqRef_Ext should be set to the current providing the desired startup torque. IqRef_Ext = 0 there is no startup
current and IqRef_Ext = 4095 is the max rated RMS current entered question 2 in MCEWizard. 

In case of current control method, control loop maintains the current reference in order to maintain the current speed keeps increasing that is the reason the speed reaches maximum RPM.


For some reason, when I try to control the speed using Vsp analog input with current control mode, the motor starts and then immediately spins in opposite direction. what can cause this issue?

VSP analog input  uses “DIR” pin for motor direction input. Toggling the DIR pin changes the direction of motor.

For more details on VSP analog input refer to Section: 2.1.13.2 Vsp Analog Input of iMOTION™ Motion Control Engine Software Reference Manual

Please let us know if any further details are required.

 

Thanks,

Krupashankar

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Hi @Krupashankar ,

Thanks for your reply.

If i have rated value of IqRef_Ext the motor ramps up too fast and with lower vale of IqRef_Ext ramp rate is normal.

But the problem with lower value of IqRef_Ext is that the the motor  steady state speed is lower.

I want low ramp rate at the same time motor to operate at maximum possible speed with rated IqRef_Ext.

which parameter to change to reduce the ramp rate and attain full rated current?

 

My another question is,

In current control mode if IdRef_Ext is set to 0, does it means filed weakening will be disabled?

Please let me know to configure field weakening in current control mode?

 

One more question,

In current control mode, when I try to run my motor in no load, it runs at 22000 RPM without any problem. 

But I have set up my maximum speed as 18000 RPM in the parameter file. How to limit the speed in current control mode?

If limiting the IqRef_Ext is the only way to limit speed, then the problem I have is after fixing optimum IqRef_Ext for one particular load when I change to a lower load the motor speed ramps up too high and then triggers gatekill ( I have explained this gate kill issue in a different thread,  https://community.infineon.com/t5/Motor-Control-ICs/Gate-kill-error-in-D111T/td-p/387807 )

 

I will summarize my requirement once again,

I want the motor to operate in constant torque (current control) mode so that for any given load the motor will be running at maximum possible speed for given rated current. At the same time my speed ramp rate should be slow. I want the motor to operate in field weakening region as well in current control model. Hope I made my point clear.

Thanks:)

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Viswa
Moderator
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50 replies posted 250 sign-ins 10 solutions authored

Hi @Vel 

 

Please go through the following document, it provides details about how speed control can be established with current control mode.

Driving high inertia loads with iMOTION™ 2.0

Best Regards

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Vel
Level 1
Level 1
First reply posted First question asked Welcome!

Hi @Viswa ,

 

Thanks for sharing that document.

I have already downloaded and had a read through that document in the past.

It doesn't have answers to my questions.

My questions are very specific. That document is very generic.

Please provide me some clear answers for my questions.

Thanks 🙂

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Krupashankar
Moderator
Moderator
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250 replies posted 100 solutions authored 5 likes given

Hi @Vel,

In case of current control mode IqRef_Ext is the only way to control the speed. There is no ramp rate to control the speed in case of current control mode.

Krupashankar_0-1671437964427.png

IqRef_Ext can be varied based on the load using the custom script. For more details on script language please refer to : How to Use iMOTION™ Script Language 

Filed weakening can be controlled based on FwkVoltLvl. This parameter specifies the modulation threshold to start field weakening.  For more details refer to section 3.2.6.5 FwkVoltLvl of iMOTION™ Motion Control Engine
Software Reference Manual 

Please let us know if any further details are required.

 

Thanks,

Krupashankar

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