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DRV8824-Q1: Adjustment mechanism when DRV8824 full-scale current is greater than motor saturation current

Amelie Zheng
Genius 10865 points
Part Number: DRV8824-Q1

Hi Team.

According to the following diagram, to avoid motor saturation, it is recommended that the Ifs current is less than the DC maximum current of the drive circuit. In this case, the corresponding current is the smallest when VM is minimum (in the case of vehicle battery voltage shortage). To ensure that the motor is not saturated in this case, Ifs The current should be set very small, but under normal voltage, because the motor driver chip is driven according to the Ifs current, its maximum output torque will be limited. If the phenomenon of motor saturation under low voltage is not considered, if Ifs is greater than the DC maximum circuit, then the How can the driver chip adjust the current when the motor saturation current cannot reach Ifs?

  • 0
    TI__Guru 56650 points

    Amelie,

    "the corresponding current is the smallest when VM is minimum (in the case of vehicle battery voltage shortage). To ensure that the motor is not saturated in this case, Ifs The current should be set very small"

    I think "in order to avoid saturating the motor" makes you confuse. When IFS setting is higher than that value, the winding current cannot reach it even the motor driver is fully on. If change it from "in order to avoid saturating the motor" to "in order to avoid saturating the motor driver", it would be more clear.

    The motor saturation should be related to the winding current, not VM voltage. So, we just need to set IFS lower than the motor saturation current or rated current.

  • 0 in reply to Wang5577
    TI__Genius 10865 points

    Hi Wang,

    thanks for your reply.

    As customer test, even the IFS> the current, the comparator will still flip. How does it achieve?

    In another word, when IFS>this equation current, how does it work and what will happend?

  • 0 in reply to Amelie Zheng
    TI__Guru 56650 points

    Amelie,

    "even the IFS> the current, the comparator will still flip." Would you ask the customer to share a waveform to show it?

    When IFS setting is higher than that value, the winding current cannot reach it even the motor driver is fully on.