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MCT8316Z: MCt8316Z SPI interface current fbk question

turguy goker
Prodigy 230 points
Part Number: MCT8316Z
Other Parts Discussed in Thread: MCF8316D

Tool/software:

MCT8316Z SPI version does have internal phase current Isense feedback however these signals are not provided outside instead used internally comparing them to external limit voltages. Is there another version of MCT8316 that provides Isense externally or another IC that does similar function with current feedback provided externally?

  • 0
    TI__Mastermind 23612 points

    Hi ,

    Thanks for posting your question.

    We are OOO this week, our response will be slow.

    Regarding your question,  the Isense in MCT8316 is used for CBC. The FOC based products MCF8316C provides many variables through I2C access .

    What is your End application ? Can you look into FOC based products?

    Thanks and Best Regards 

    Venkatadri S

  • 0 in reply to Venkatadri Shantaram84961
    Prodigy 230 points

    Our application does not have the capability to turn motor for self alignments and self calibration which is required by FOC. We need to use Hall based sensors to commutate. Current fbk is needed to provide a closed loop current inner loop where outer position loop demand can be a torque value. Also current fbk will be used to predict frictional loads as part of an optimization, adaptive control concepts. 

    I realize this chip does nt provide direct pin for current feedback; does it have SPI based current reading capability?

    Also SPI version and even Hardware version has limited dir control with commutation tables. This prevents device to perform in true 4 quadrant mode. Like to know if any future plans for these functionalities?

  • 0 in reply to turguy goker
    TI__Mastermind 23612 points

    Hi,

    Thanks for sharing the details. I will respond by end of this week.

    Thanks and Best Regards 

    Venkatadri S 

  • 0 in reply to Venkatadri Shantaram84961
    Prodigy 230 points

    please respond to latest question. 

  • 0 in reply to turguy goker
    TI__Mastermind 23612 points

    Hi

    I will respond by Monday.

    Thanks and Best Regards 

    Venkatadri S 

  • 0 in reply to turguy goker
    TI__Mastermind 23612 points

    Hi,

    Understood about the need of Hall sensor. Just for your information FOC device has IPD (Initial position detection feature) without turning the motor.

    There is not current sense data for SPI variant also.

    Can you clarify 4 quadrant need? Direction control will change direction according to DIR pin status for Hardware variant and SPI variant through DIR value in control register.

    Thanks and Best Regards 

    Venkatadri S

  • 0 in reply to Venkatadri Shantaram84961
    Prodigy 230 points

    Use of FOC wo turning motor is very interesting. Do you have references anywhere that i can read. Also I am very interested in MCF8316D version of this chip . 

    4 quadrant is like you have a large load and you are moving the load down with high speed and as you reach your position the deceleration is gets high due to fast stop requirements and dire changes driver must apply current in opposite to rotation and as system stops to hold position in position servo hovering mode dir can change dynamically .

  • 0 in reply to turguy goker
    TI__Mastermind 23612 points

    Hi TG,

    As you said rightly FOC devices provided fast deceleration without causing voltage spike. The feature is Active deceleration.

    About active deceleration (+) [FAQ] MCF8316A: Fast deceleration using active braking in MCF8316A and MCF8315A - Motor drivers forum - Motor drivers - TI E2E support forums

    In the link MCF8316A data sheet, product information and support | TI.com go to technical article section for the tuning guide,

    Please note you can chose MCF8316D/15D/ 16C/15C which are recent with many new features.

    I will share the comparison document soon which I am working on.

    Thanks and Best Regards 

    Venkatadri S 

  • 0 in reply to Venkatadri Shantaram84961
    Prodigy 230 points

    Great thanks for this info. FOC is for sure maybe the way to go. but mechanism we have robot is not friendly for FOC self tuning. If FOC tuning is done and we loose power is there a way 8316D remembers cal values and position of the rotor especially is rotor is tuned when power is off. And regarding 4Q control yes dynamic brake can help fast decel however when controlling position of a load with gravity acting and frictional components and mechanical hysteresis plus dead band related non linearities. However when controlling position with in loop non linearities, the position servo output which can be ideally current demand to driver IC can move in between quadrant that requires linear control as motor and driver is moving thorough various combination of 4Q zones. This is what I like to understand how 1PWM synchronous and asynchronous tables work.  Can you please also discuss the use of these two tables which is designed in nearly all BLDC drivers with Hall signals and compare this to FOC control. Also i see lots of articles on FOC , hall commutation, trapezoidal waveforms etc for various drivers but No white papers at all how to use the commutation tables as I mentioned above for a true 4 Quadrant operation. This is what I need.

  • 0 in reply to turguy goker
    TI__Mastermind 23612 points

    Hi TG,

    Can we re create a new thread for the recent question about details about the architecture.

    We will close this thread so that topic reference will be documented for future reuse.

    Request to start new thread.

    Thanks and Best Regards 

    Venkatadri S 

  • +1 in reply to Venkatadri Shantaram84961
    Prodigy 230 points

    OK you can close this and I will compose a generic Q regarding 4Q mode with current 1XPWM Synchronous table or a new variation of 1XPWM table for controlling position of a mass with gravity for both high deceleration, acceleration and holding mode  where 4Q operation is required. How to do this with Hall based commutation and making sure circulating currents and shunt resistor current signals.