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DRV8886AT: the speed issue: 1080rpm.

Xianrong Shang
Intellectual 855 points
Part Number: DRV8886AT

Hello.

Now I plan to use the DRV8886AT on the two-phase hybrid bipolar stepper motor driver. the stepper motor full step mechanical Angle is 1.8 °, 12 ~ 28 VDC driving voltage, phase current of 1.3 A, 1.5 Ω coil resistance and inductance 1.25 mH, speed 90 ~ 2100 RPM. and the 2100 RPM corresponds to the current frequency is 1.75 KHz.

In fact we need is: 12 ~ 24V drive voltage, demand rate of 7200 PPS, which is 1080 RPM, current frequency of 900Hz.

But  I'm afraid the DRV8886AT can't reach 1080 RPM at 12V, namely the current frequency of 900Hz. I don't know whether it meets the above requirements, 1080RPM. or Could you please recommend other better Sine wave driver IC ?

  • 0
    TI__Genius 14485 points
    Hi Xianrong,

    What is the issue you are seeing with the driver? Does your motor not exceed 1080 RPM when you drive it? Can you achieve speeds higher than 1080 RPM at 24-V?

    According to the datasheet, the STEP pin of the DRV8886AT can receive signals up to 500 kHz. I think the DRV8886AT should be able to accommodate your step rate requirement.

    The things that limit stepper motor step rate are resistance, inductance, supply voltage, motor load, speed (due to back EMF), and micro stepping. Can you try a larger microstep size to achieve your desired speed at 12 V?
  • 0 in reply to James Lockridge19
    Intellectual 855 points

    Hi， James.

     I received the DRV8886AT EVM board yesterday.  the test result is not satisfied.

    Below is the comparison test，use DRV8886ATEVM and use H company drives (the main core part is DSP + MOSFET), blue for DRV8886ATEVM test current waveform, white drive test waveform for H company, both comparisons are as follows:

    the condition is: the driving voltage is 12V, 1.1 A peak current, current frequency 498 hz, both of them use Auto most cerebral sci-film Ripple Control, 1/16 step driving mode.

    Difference:

    1. Please note the square mark:  blue for DRV8886ATEVM test current waveform, white is the competitor H company,  the ripple of the motor that DRV8886ATEVM drives is bigger than H company .

    2. According to the situation of the above drive motor after 2 H, DRV8886ATEVM driven motor temperature is 65 ℃, and H company drive motor only 48 ℃. (the test environment for office, 26 ℃).  the temp of the motor that DRV8886ATEVM drives  is higher than H company .

    3. Listening with ears motor noise,  the noise of the motor that DRV8886ATEVM drives is louder than H company .

    4. Feel with the hand motor vibration,  the vibration of the motor that DRV8886ATEVM drives  is stronger than H company.

  • 0 in reply to Xianrong Shang
    TI__Genius 14485 points
    Xianrong,

    Can you try the Dynamic Decay setting rather than Ripple Control setting on the DRV8886AT? Sometimes Dynamic Decay has better acoustic performance than Ripple Control. Motor parameters and operating conditions can sometimes cause one setting to work better than another.

    Regarding your comments on temperature rise, did you control all the variables in your experiment? The DRV8886AT shouldn't heat the motor more than any other solution that creates a sine wave with the same RMS current. For a good thermal test, I recommend ensuring the motor is at room temperature when you start driving it. After a fixed amount of time, measure the temperature. If the motor was already warm from previous testing, then it will appear hotter when you measure it.