Motion Control and Motor Drives

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Connecting Hall Effect Sensor as an encoder(feedback) for PCI 7356 Motion Controller

Hi,

 

We have Labview 2010 and the following hardwares for testing a specific motor (a brushless DC motor):

NI PCI 7356 Motion Controller

NI UMI 7774

AKD Servo Drive P00606

 

However, I met some difficulty when wiring the motor to the motor drive(and controller). In the manual, it says PCI 7356 needs encoder signals as the feedback. But our motor doesn't have a built-in encoder. It has three Hall Effect Sensors, which we plan to use as an encoder. If we feed the hall sensor signals as the encoder phase signals (Phase A, B) to the drive/controller, I wonder if Labview or PCI 7356 (after an appropriate configuration) can adjuct the phase (from 120 degree to 90). Does it work even without the adjustment?

 

If the above doesn't work, can I feed only one Hall Effect sensor signal as Encoder Phase A and don't feed anything to Phase B (since I only need control the motor speed in one direction)? Will PCI 7356 or Labview recognize the signal and function accordingly?

 

If it doesn't work as well, could I use motor's Back EMF as a feedback (this motor produces a decent sinusoidal back EMF)? If I can, how should I configure the hardware and wire the motor to controller accordingly? 

 

If all three above don't work, could you suggest a way to solve this problem?

 

Thanks so much for your help.

 

Best,

Chen

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Dear Chen,

 

I am not sure if you are able to connect the hall effect sensors as feedback to the motor position or velocity. I will ask some colleagues and confirm the answer to you.

 

If this is the case, you will have to buy an encoder and place it in your setup.

 

Regards,

A. Zaatari

National Instruments
Applications Engineer
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Hi,

 

I have another question. We also purchased Motion Assistant software to help us write Labview. I'm new to both softwares, so I read examples/templates. However, the manual/examples I have seen online don't meet my objective. My objective is during a certain period of time (around 90s) I can control the motot's acceleration/deceleration and motor's rpm with a PID control and measure/minimize the vibration and noise during this process. I wonder if Motion Assistant is helpful in this case. If not, how could I write such a program in Labview? Thanks so much for your help.

 

Best,

Chen

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Hey Chen,

 

I have comfirmed that the PCI card will not be able to do feedback with the hall effect sensors. However, you could do that with our NI 951x modules if you run it in FPGA mode. You would need an extra IO module to set up the hall effect sensors with, but you could effectively customize your control and your feedback on the FPGA board immediately. 

 

For your other post, I am not sure you can create a time constraint on the move, I believe that when you define a motion, you would need to define the number of steps or the position and not the time. If you are running the motor at a specific velocity for an amount of time, you would need to set that as the number of revolutions and not time.

 

I hope this helps.

 

Regards,

A. Zaatari

National Instruments
Applications Engineer
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Hi,

 

Thanks for your reply. Since we already bought PCI 7356, we don't plan to change the controller. So I guess I just get a motor with an encoder. Also for the Labview question, are you sure that Labview is not capable of doing time constaint? Since I have to build a motion profile with something like accelerate to certain rpm within x seconds (x is the variable this case). Even if I can control the speed by counting the revolutions, I don't think it works for acceleration this way.Could you provide some hint about controlling the acceleration/deceleration? Thanks for your help. 

 

Best,

Chen

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