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About the problem of DRV8818EVM (vibration and heat)

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Other Parts Discussed in Thread: DRV8818EVM

Although the motor is driven by DRV8818EVM, vibration and heat of a motor are large.
Although it seems that the elegance of the other company does not have most vibration, is this the feature of DRV88 series?
A customer's spec. is written to below.
---------------------------------
- 24VM/1.5A
- A motor is an oriental motor :P K243DA
* There is likely to be no mistake in connection.
- Ichop:1.5A
- Slow decay
- Full step
 ⇒1/8 step is used, vibration will decrease, but it remains.
- Even if it makes speed quick and makes it late, it vibrates.
(Vibration has little quicker one)
- Even if it makes current small, vibrate.

-A circuit uses DRV8818EVM as it is.


[DRV8818EVM specification]
- Start speed:128
- Target speed:200
- Sync Recirculation is check
- Accel rate:50
* Although he would like to set Ichop to 1.5A, Vref is then set to 1.7V.
Is it reasonable although the formula of a datasheet is differed from?
---------------------------------
Thank you for your consideration.

  • Hi Satoshi,

    Can you provide the specs or link to the motor?

    Can you get a scope capture of the current through the motor coil? This will provide a lot of insight.

    Please ask them to utilize the MIXED DECAY mode and see if that has any effect.

     

    I am confused by your last request on Ichop, please clarrify.

  • Dear-Nick-san

    Thank you for the advice.
    DRV8818EVM was borrowed and evaluated to the customer.
    The motor used 103H5205-5254 of SANYO.
    (There are 24V, 1A, 1.8°Step, and not a datasheet)
    A result is written to below.
    ----------------------------------
    The measured waveform is attached.
    (ch1:VAOUT1, ch2:IAOUT1, ch3:VAOUT2)

    - The waveform of a full step
    Even if it changes Decay, change is nothing to a waveform.

     

    - The waveform of 1/8 step
    * It is 0.6V (Fast Decay) about Vref of Decay.


     

    * It is 1.6V (Mixed Decay) about Vref of Decay.

    The noise to which Vref resembled the time of Fast Decay in at least 1.2V occurred.

     

    * It is 2.0V (Slow Decay) about Vref of Decay.


    [Others]
    Although 1/2Step, and 1/4Step were not about 1/8, either, it became the current waveform similar at the time of Slow Decay.

    [Guess]
    I think that, as for Fast Decay, the noise influenced, as for Slow Decay, speed of response influenced, and the current waveform collapsed.
    ----------------------------------

    [An additional question]
    Only as for Vref:1.6V, Mixed Decay at the time of 1/8Step was stabilized.
    For example, is it set to Mixed Decay of operation near Slow Decay at the time of Vref:1.9V?
    Vref: Is it set to Mixed Decay of operation near Fast Decay at the time of 1.0V?
    Does Mixed Decay change operation by Vref (0.7V~2.0V)?

     

    Best Regards,

    Satoshi