Modulating the width of the P70530 stepper drive output pulses

[ben64]

I'm using a NI-PCI-7332 controller with a UMI-7772 and a P70530 drive to qualify a stepper motor (using LabVIEW 8.5). One of the test to perform is to lower the drive amplitude level until the motor stall.

I'm controlling the drive input supply by GPIB (using an HP6032A system supply) but the problem is that the amplitude at wich the motor stall might be below the 20V specified lower limit of the P70530 (the motor lower drive value is specified at 23V).

Using my actual hardware would there be a way to modulate the width of the drive pulses to the motor to get a lower RMS output (and will it work)? If not, do somebody has any suggestion of the hardware to use to perform this task?

Thanks,

Ben

[DjDaveNI]

Hello ben64,

You should use the software (via GPIB) to lower the drive’s current output to the motor. You can do this in real-time while the motor is running.

However, if you decrease the power supply to the drive you may not get the point where the motor stalls but rather the point at which the drive fails/browns out/chokes.

I hope this helps you out 🙂

[ben64]

Hi Dave,

Thanks for responding to my post. My goal is to characterize a motor so it is the bus voltage that I want to lower until the motor stops running and I want to disable the chopper and sense circuits. I will finally build my own driver using L297 and L298 ICs from SGS-Thomson (the L298 has a threshold voltage of 4.8V).

I built my custom driver last week and I'm currently trying to make it work with the NI PCI-7330 controller and NI-UMI-7772.

Thanks again.

Ben