DRV10866 Open loop jump motor speed

Hi Krushal-san,

 Thank you for your support.

 I understand. 

Thanks,

Shimizu

Hi Krushal-san,

I have two question about this post.

Q1. How mechanism is 18Hz measured?
Q2. Is the following waveform jumped open loop?
After operating motor over a certain speed, we tried to become input PWM to low level for the moment.
In re-operation, FG is about 480Hz.

Thanks
Shimizu

Hi Krushal-san,

Thank you for your support.
I understand that it needs measurement time interval between BEMF zero crossing for direct closed loop.

I add two questions.

Add Q1:
Does Open loop operation execute for measurement time interval between BEMF zero crossing?
In other words, Direct closed loop is include instantaneous open loop for measurement time interval between BEMF zero crossing?

Add Q2:
Please see the below picture.
After PWM under 500us low level is inputed, Closed loop starts after 4ms
What does DRV10866 do for about 4ms without measurement time interval between BEMF zero crossing?
Does it need time from standby mode to active mode?

Thanks,
Shimizu

Hi Krushal-san,

Thank you for your support.
I can't understand the detail measure way whether the motor speed of coast is more than 18 Hz for jump Open loop.

　Add Q:In your previous post, There is the following words,
　　　　    "It changes based on coasting speed of motor during off state."
              I can't understand this words.

             Does it mean the following state cycle? 100 duty? or other way?
             Could you tell me the difference of "Open loop" and "Measure way whether the motor speed of coast is more than 18 Hz"?

Regards,
Shimiuz

Hi Krushal-san,

Thank you for your support.
I understand the following.
1. When motor is restarted, DRV10866 measures the motor speed based on time interval between each BEMF zero crossing.
2. If measured speed is greater than 18 Hz then motor skips open loop and goes into close loop directly.
3. DRV10866 measures interval between 4 consecutive back emf zero crossing to verify that motor is spinning at certain minimum threshold.

I add same question.
I need more detail for supporting this Biz.
I will lost this Biz if I cannnot ansewr this detail to costomer. 　

About above 3.
 - When motor is restarted, Does it correct that Bemf detection phase for FG signal is selected by counting twice of BEMF?
   Or 4 times?
   ->In other words, I case of being selected W phase as FG signal generation, "W phase * 2" or "W phase * 4"?
   I would like to know the reason of being fixed as Bemf detection phase for FG signal. 　

About above 1.
 - When motor is restarted, Does it correct that DRV10866 compares COM pin and each pahse at corst state of DRV10866 internal H bridge FET?

 - When motor is restarted, Does DRV10866 detect Bemf with following sequence?
    W->U->V->W->U->V....
      * This is OFF pin sequence of Table1 in datasheet. more detail is State1-> 6 -> 5 -> 4 ->....

- When motor is restarted, Is there rule of time period limitation to detect Bemf at each phase?
  or Does DRV10866 detect Bemf at W phase all during 14ms? and then, If over 14ms, Does DRV10866 go to open loop?

If there is not rule of time period limitation for detecting Bemf at each phase, Could you tell me trigger by which detection phase of Bemf is gone to next state?

Regards,
Shimizu

Hi Krushal-san,

Thank you for you reply.
I tried experimentation in case of jumping open loop at my bench.
Please see the attached file.
In case of jumping open loop by stopping PWM input for a moment, Phase for generating FG signal is fixed to V phase in I and customer.
Customer tried over 100 times. In all time, Phase for generating FG signal is fixed to V phase.

In this method of stopping PWM input for a moment, Why is phase for generating FG signal fixed to V phase?

DRv10866.pptx

You showed at provious post the following words.
"All phases are combined inside DRV10866 and it starts detecting BEMF zero crossing combined on all phases."
I can not understand mechanism of jumping open loop in only this answer.
Please tell me more detail mechanism of jumping open loop?

Best regards,
Shimizu

Hi Krushal-san,

 I am sorry that I am asking many questions.

 How is the progress? 

Best regards,

Shimizu