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DRV10983-Q1: Application which needs to hold a BLDC-motor at a specific position

Tom Lightning
Intellectual 305 points
Part Number: DRV10983-Q1
Other Parts Discussed in Thread: MCF8316A

Hi,

at the moment I'm doing some research for an application at which I need to fulfill the following points:

  • Controlling the output-shaft position with an accuracy approx. +/- 1.5° (between output-shaft and BLDC-motor will be a gear ratio of approx. 1:150 to 1:200)
  • Holding a specific position actively against a specific torque (that means generating torque at zero speed)

I have seen that there are sensorless control algorithms (Trap, Sine, FOC) that don't need any position sensors to work. The DRV10983-Q1 is one of those ICs that commutates the BLDC sensorless. My Question is, is there any chance to comply with the points above by using a sensorless based control algorithm? Or is for this application a sensor based FOC with three hall sensors the only way to go?

One attempt could also be to place a single hall sensor at the rotor to detect the magnetic polejumps and use this information as indicator to know when to active the DRV10983-Q1 so that power is going to be applied to the motor to either hold it at a specfic position or to count steps to get information about the travelled range.

Many thanks

Tom

  • 0
    TI__Mastermind 18916 points

    Hi Tom, 

    Our team will take a look at this tomorrow and try to provide a response by end of this week or early next week. Thanks! 

    Best Regards, 
    Andrew 

  • 0
    TI__Mastermind 24405 points

    Tom,

    DRV10983-Q1 can be used for controlling position with a gearbox as you mentioned but it does not have the feature to brake and hold the rotor with load. I would recommend you to check MCF8316A (Product page link: www.ti.com/MCF8316A) which is also a sensorless driver that operates based on FOC and can hold the rotor with load.

    Regards,

    Vishnu

  • 0 in reply to Vishnu Balaraj
    Intellectual 305 points

    Hi Vishnu,

    for my understanding the MCF8316A is not an automotive qualified motor driver, isn't it? Beside that fact, how is the IC able to hold the position sensorless?

    The following training from TI states, that applications which require torque at zero speed are always sensor based:

    1.3 Demystifying BLDC motor commutation: Trap, Sine, & FOC

    Do I only have to pullup the brake pin high to lock the position and withstand a specific torque?

    Best regards

    Tom

  • 0 in reply to Tom Lightning
    TI__Mastermind 24405 points

    Tom,

    MCF8316A is not automotive qualified part.

    MCF8316A uses "Align braking" to brake the motor. However, the device does not have the capability to apply brakes at certain angle. User has to monitor the angle and command the device to apply align brake. "Torque at zero speed" means that the sensorless drivers cannot generate sufficient torque at zero speed, so sensors are required to commutate the right phases to generate maximum torque at zero speeds. 

    You can either pull the hardware BRAKE pin or configure the BRAKE_INPUT register to override the hardware brake pin and apply brakes over I2C communication. 

    Regards,

    Vishnu

  • 0 in reply to Vishnu Balaraj
    TI__Mastermind 26046 points

    Hi Tom,

    Do you need assistance on this still? If not, please mark as Resolved.

    Thanks,
    Aaron

  • 0 in reply to Aaron Barrera
    Intellectual 305 points

    Hi,

    so that means that TI don't have any AEC-Q qualified ICs with an embedded control algorithm (sensorless) which can complie with the mentioned requirements? Let us assume that the motor does not need to hold against a constant torque to hold the motor at a specific position, can you make a statement about how accurate I can control the postion of the motor with an IC that has an integrated control algorithm (sensorless)? Or would you always suggest to use a sensor based commutation method to handle such applications?

    BR

    Tom

  • 0 in reply to Tom Lightning
    TI__Mastermind 24405 points

    Tom,

    Correction! MCF8316A has the capability to brake at a certain angle that can be configured by the user. Here are the steps:

    1. Select Motor stop option [MTR_STOP] as "Align braking"

    2. Select Brake pin mode [BRAKE_PIN_MODE] to "Align brake".

    3. Select align brake angle select to "Use ALIGN_ANGLE configuration for align braking".

    4. Select the align angle "ALIGN_ANGLE" to any angle at which you want to apply brakes. 

    5. Select Brake pin override as "Override hardware pin and brake according to BRAKE_PIN_MODE"

    6. magnitude of the align current can be configured in [ALIGN_OR_SLOW_CURRENT_ILIMIT].

    On the AEC-Q qualified ICs, we have an automotive qualified device with same algorithm features and pin mapping in our roadmap and we expect to have the samples by end of this year. 

    Regards,

    Vishnu.