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STEPPER MOTOR DRV8432

Andi Lamce
Prodigy 10 points
Other Parts Discussed in Thread: INSTASPIN-BLDC

Hi,

hi,
I'm using the driver drv8432 to drive a stepper motor with features that are listed in the photo.
The wiring diagram I'm using is what is recommended in the demo board. For safety, I will also put in the wiring diagram. The values ​​of the various components are the same as the demo board.

What I wanted to ask, and I hope to be as clear as possible, is that while I go to low frequencies, the stepper motor seems to be working well. When I try to increase the speed and thus increase the frequency (change of speed I do it very slowly so there should be no problem-of-step) the stepper motor after a certain frequency, no longer turns. The currents in the two phases are very low, while I wait for them high. What happens is that as microstepping mode the output current at low frequencies in the shape of a sine wave and that is fine to me, when increasing the frequency  the sine wave is shifted with respect to the phase voltage (much). I also tried to drive the motor in full step mode but the problem still exists. In the picture I show the various forms of PWM control to the driver DRV8432.

The fundamental problem is that the currents in the phases are very low: 0.4 A current while I expect much higher result with the consequence loss of step.

I ask you where wrong and how can I increase the phase current and speed?

the supply voltage for the driver is 30 V.  I use a power supply that can deliver up to 3A.

thanks in advance

A.L.

  • 0
    Intellectual 840 points

    http://www.ti.com/lit/ds/symlink/drv8432.pdf page 3
    MODE SELECTION PINS
    you do have it set to cyvle by cycle current limit.  Also page 7 gate suply votage under voltage protection, the specs for the bipolar stepper shows it as a 4 wire, 3.6V motor, it may be under voltage protection causing an issue.
    Everything looks good otherwise, with what you have already, the only thing i can think of is try out the instaSPIN tool.

    http://www.ti.com/tool/instaspin-bldc

    hope pointing you to that tool helps,

    Eric

  • 0 in reply to Eric Blenner-Hassett
    Prodigy 90 points

    Hi,

    You do not write at what step frequency you get this problem.

    But hopefully you are aware that stepper motors require a high voltage if you need to go up in speed. This is caused by the high inductance of the windings.

    It is common to monitor and control the current through stepper motors. Commercial drives often runs the motor at rated current while moving and a lower current when at a standstill. As you increase the speed there will at some point not be enough voltage available to maintain the required current.

    You can find a good primer on step motors and control here: http://homepage.cs.uiowa.edu/~jones/step/