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DRV8823-Q1: increasing Motor Torque

Part Number: DRV8823-Q1
Other Parts Discussed in Thread: DRV8823

Dear TI Experts

We are using DRV8823,  when the temperature is -40℃,the motor is hard to start!

And the motor supplier told us to increase the input voltage to increasing Motor Torque,now the driving voltage is 18V

1. If we increase the voltage, eg 32V ,the designed driving current is constant, can the output torque of the motor be improved?

2. If we increase the voltage,Will the internal current loop become unstable, affecting constant current drive?

3.Comparing the two ways: increasing voltage and driving current by changing resistance, which way is more reasonable to improve motor output torque?

  • Hi Qianqian,

    1. If we increase the voltage, eg 32V ,the designed driving current is constant, can the output torque of the motor be improved?

    Yes, the output torque can be improved by increasing the driving current. This assumes there is margin to increase the driving current.

    2. If we increase the voltage,Will the internal current loop become unstable, affecting constant current drive?

    No, the internal loop should not become unstable. The internal loop will attempt to regulate the current at the limit set by xxVREF, xI[2:0] and ISENx.

    3.Comparing the two ways: increasing voltage and driving current by changing resistance, which way is more reasonable to improve motor output torque?

    This depends on the motor parameters. In this case, changing the driving current is probably more reasonable because 32V is the recommended maximum. There is no margin for power supply variation.

  • I want to double check with you again,

      the output torque can be improved by increasing the input voltage?

  • Hi Qianqian,

    The output torque can be improved by increasing the input voltage if Ichop (Equation 1) did not limit the current at the lower voltage.

    If the current is being limited at the lower voltage, increasing Vrefx or decreasing Risense is required.

  • Hello Rick

    Thank you for your help~

    Now our input voltage is 18V ,designed current is 250mA,We are evaluating two ways to improve the output torque

      1. Increase current, from 250mA to 300mA

       2.Increase input voltage, from 18V to 32V

    According to your reply above, increase current is better, am I right?

  • Hi Qianqian,

    Increasing current is better.