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DRV for reversing motor design

user4124807
Prodigy 90 points
Other Parts Discussed in Thread: CC1350, DRV10975, TIDA-00525, DRV10974

What is the recommend minimal configuration for a 12V 0.5A BLDC Fan Motor that with variable speed control and the possibility to change rotation direction.

Can this be achieved without direct MCU control for example with PWM input to the DRV. For example duty < 50% = cw , duty>50% = ccw.

I would prefer  a sensor-less design because of the ease of the motor.

If MCU is needed, please suggest a configuration and design example.

Production will be about 10k unit per year. (no over-spec. suggestions please. )

Do you have motor control examples for CC1350? If possible I want to control the motor directly via Sub-Giga band.

  • 0
    TI__Prodigy 575 points

    Hello user4124807,

    Here are some answers along with some questions:

    1. For a 12V, 0.5A, sensorless BLDC fan motor, from TI's existing portfolio I would recommend the DRV10975.
    2. When do you have to start the evaluation? If this project can wait until late January 2018, we will have a new device coming out for sampling - let's call it device "X" for now. DRV10975 requires some parameter configuration through EEPROM; X eliminates all the EEPROM programming but maintains the same efficient, quiet fan motor operation. If you're interested, you can come back to us around Jan 19 and we'll point you to "X".
    3. Question: what is the max operating voltage / max current?
    4. If you're already using CC1350 in your design, you can just assign one GPIO to toggle between H and L and connect this GPIO to the DIR pin (direction) of DRV10975. This will allow the fan motor to spin CW and CCW. You can find the details of this pin in DRV10975 datasheet. The exact same pin will also exist on "X".

  • 0 in reply to Zhao Tang
    Prodigy 90 points
    Dear Zhao,

    Thank you for you quick replay and detailed explanation.

    Usually, fan-motor`s are running only in one direction, therefore I assumed that most of low power motor driver are only for single direction.
    But we ha a special application where we have to change rotation direction during operation. In the current design we used a single phase BLDC motor with 2 hall sensors, one for each direction. For PWM generation we used 8-bit MCU. Now for the new product design I want to use a 3 phase sensor-less BLDC. Then, the 8-bit MCU will not work anymore but a DSP for such a small motor is also overkill (and probably too expensive) .

    I had a look to the documentation and application notes of your DRV10975, but I am thru completely with them.
    Change of the direction is the most critical part. Can I change direction during closed loop operation or do I have to stop the motor before???

    By the way, I also a look to your user guide TIDA-00525 and ask our responsible sales person from Sunon for a sample of the motor you used in your report(Sunon BLDC fan model SG40281B1) to perform similar tests buy myself. But I have been toked that this type is no anymore in production jet. SG40281B1 is a inner-runner motor, now there are only outer runner in production. the same size would be VG402...
    I will try one for my reference.

    I will start design with DRV10975 and then switch over to 'device x'.
    Hope it will be pin-compatible.

    Concerning 3. your Question: what is the max operating voltage / max current? =>12V
  • 0 in reply to user4124807
    TI__Prodigy 575 points

    Hello user4124807,

    You can change the direction of motor spinning on the fly in closed loop. The motor will first stop spinning and then start to spin in the opposite direction.

    The device X requires much less configuration and hence will not be pin compatible (fewer pins on device X). So my 2 cents is that you can either try out both, or if you want to minimize your eval efforts, you can stick with one depending on project schedule.

    Given our communication I consider this thread closed. Please help click on the resolve button if you agree, and if you have further questions please feel free to submit another question.

    Happy new year to you and your family!

  • 0 in reply to Zhao Tang
    Prodigy 90 points

    Dear Zhao

    thank you for your continues support.
    For the first trial I ordered DRV10975EVM. Hope it will be delivered soon.
    My most concern is, doing direction change on the fly is tuning of the slow down and restart parameters.
    Because we have to do direction change in a small time window and also have to care about peak current and noise(i mean the noise you can hear by your ears, not the electrical noise).
    I think this features can be tuned enough by the EEPROM settings, but what`s about the tuning of 'device x' ?
    Please keep supporting during evaluation and give me a message when 'device x' will be opened.
    I also still he some questions about the register settings:
    SysOpt1 & SysOpt2
    RvsDrThr[1:0]
     what does 'the threshold where device starts to process reverse drive or brake' mean.
     Is the motor above the threshold freewheeling?
     Is it ok to set RvsDrThr close to closed loop operation speed.
    OpenLCurr[1:0]
     is it the max current which is allowed during startup?
    BrkDoneThr[2:0]
     time from Closed-loop to stop completely?
    SysOpt3
     can you pleas point the formula for Open loop start-up acceleration 
    Is it possible to do ICP at the DRV10975 by I2C?
    I did not find any documentation about. Please point out.
    Today, I installed the DRV GUI(SLOC312) and had may troubles, because I installed the recent LabView Runtime Engine. Finnaly I recongnized that the GUI only works with the LabView Runtime Engine from 2014.
    Best Regrads
    Christian
  • 0 in reply to user4124807
    TI__Prodigy 575 points

    Hi Christian,

    1. We certainly will work together when you start evaluating device x. The best way to make sure you immediately get an update when device x is out is to submit another question on E2E after this thread is closed on Jan 19; alternatively, if you could leave me with an email address, I can personally ping you when device x is up on ti.com.
    2. RvsDrThr[1:0]
      what does 'the threshold where device starts to process reverse drive or brake' mean
      Please refer to Figure 11 on DRV10975 datasheet (see below). When direction changes, DRV10975 waits until motor speed reaches below this threshold to turn to the next state.
      Is the motor above the threshold freewheeling?
      Yes, the motor will coast until motor speed falls below the threshold mentioned above
      Is it ok to set RvsDrThr close to closed loop operation speed.
      As long as the motor can fully stop and successfully restart in the opposite direction, it should be fine. Please confirm this with your motor.
    3. OpenLCurr[1:0]
      is it the max current which is allowed during startup?
      Yes this is the open loop current limit at startup that allows the motor to reliably accelerate to the open to close loop handoff threshold. Please refer to section 8.4.4 on DRV10975 datasheet for more details.
    4. BrkDoneThr[2:0]
      time from Closed-loop to stop completely?
      Brake Done Threshold is the duration for which Brake is applied when device enters Brake state. Please refer to Figure. 11 mentioned above.
    5. can you pleas point the formula for Open loop start-up acceleration 
      Please refer to section 8.4.3.6 on the datasheet.
    6. Is it possible to do ICP at the DRV10975 by I2C?
      What do you mean by ICP? Do you mean OCP (over current protection)? For over current protection, the OCP threshold is hard coded as 3A minimum. You cannot configure it by I2C.
  • 0 in reply to Zhao Tang
    Prodigy 90 points

    Dear Zhao,

    would you pleas so nice to introduce device x to me.

    Also regarding your last message, 6. Is it possible to do ICP at the DRV10975 by I2C?

    with ICP was meant 'In Circuit Programming'. With MCU`s it is usually possible to program them after assembly to the PCB In the Circuit by only attaching 3~4 wires.

    I wanted to know if tins can be done in a similar way with the motor-drivers.

    Best Regards

    Christian Deutnger  

  • 0 in reply to user4124807
    Prodigy 90 points

    It seams that "device x" is not out yet?

  • 0 in reply to Zhao Tang
    Prodigy 90 points


    Dear Zhao,

    would you pleas so nice to introduce device x to me.

    BR

    Christian

  • 0 in reply to user4124807
    TI__Prodigy 575 points

    Christian,

    Thank you for the reminder!!!

    Here you go with device "X": DRV10974. 

  • 0 in reply to Zhao Tang
    Prodigy 90 points

    Dear Zhao,

    Thank you for product introduction.

    I checked immediately the data sheet. 

    the [DIR]-PIN from the DRV10975 has been disappeared.

    There is a [FR]-PIN, but can it change direction on the fly?

    sorry, I could not find any detailed explanation on the datasheet.

    BR

    Christian

  • 0 in reply to user4124807
    TI__Prodigy 575 points

    Christian,

    Sorry for my delayed response. Yes you can change the motor spinning direction on the fly using the FR pin. The motor will first coast down to a certain low speed level and then the device will start driving the motor in the opposite direction.