SLVAFF1 January   2023 DRV8452 , DRV8462

PRODUCTION DATA  

  1.   Abstract
  2.   Trademarks
  3. 1Power Efficiency of Stepper Motor Drivers
  4. 2Auto-Torque
    1. 2.1 Auto-Torque: Learning Principle
      1. 2.1.1 Configuring Auto-Torque Learning Routine
    2. 2.2 Current Control
      1. 2.2.1 Setting Current Control Parameters
    3. 2.3 PD Control Loop
    4. 2.4 Impact of Auto-Torque Tuning Parameters
      1. 2.4.1 Impact of Learning Parameters on Load Transient Response
      2. 2.4.2 Impact of ATQ_UL, ATQ_LL Hysteresis
      3. 2.4.3 Impact of Load Profile on Power Saving
      4. 2.4.4 Adaptive ATQ_UL, ATQ_LL
      5. 2.4.5 PD Parameter Dependency Curves
        1. 2.4.5.1 Dependency on KP
        2. 2.4.5.2 Dependency on KD and ATQ_D_THR
        3. 2.4.5.3 Dependency on ATQ_FRZ and ATQ_AVG
        4. 2.4.5.4 Dependency on ATQ_ERROR_TRUNCATE
      6. 2.4.6 ATQ_CNT at Different Motor Speeds
      7. 2.4.7 ATQ_CNT at Different Supply Voltages
      8. 2.4.8 Motor Temperature Estimation
    5. 2.5 Efficiency Improvement With Auto-Torque
  5. 3Case Studies
    1. 3.1 Application 1: ATM Machines
      1. 3.1.1 ATM Motor Operating Conditions
      2. 3.1.2 ATM Motor With Auto-Torque
    2. 3.2 Application 2: Textile Machines
      1. 3.2.1 Textile Motor Operating Conditions
      2. 3.2.2 Textile Motor With Auto-Torque
    3. 3.3 Application 3: Printer
      1. 3.3.1 Printer Motor With Auto-Torque
  6. 4Summary
  7. 5References

2.4.1 Impact of Learning Parameters on Load Transient Response

As mentioned in Section 2.2.1, the choice of ATQ_TRQ_MIN and ATQ_UL influenecs how the control loop responds to load torque transients. This is shown in Figure 2-8 to Figure 2-11.

For all the following traces, from top to bottom: load torque, coil current, supply current:

GUID-20221117-SS0I-NHXP-PSLM-KLKZKSZ697VW-low.pngFigure 2-8 ATQ_TRQ_MIN = 0.6 A, ATQ_UL = 40
GUID-20221117-SS0I-RSD2-LBSG-ZZ2XCKV73GXX-low.pngFigure 2-10 ATQ_TRQ_MIN = 0.93 A, ATQ_UL = 50
GUID-20221117-SS0I-XHZL-R0SP-LGRHGBWCGDPH-low.pngFigure 2-9 ATQ_TRQ_MIN = 0.74 A, ATQ_UL = 45
GUID-20221117-SS0I-9D6Z-R8RQ-DXCWNRHSVD7S-low.pngFigure 2-11 ATQ_TRQ_MIN = 1.2 A, ATQ_UL = 60

  • In Figure 2-8, with lowest ATQ_UL, the motor current reaches ATQ_TRQ_MAX earlier than the other settings. This setting therefore saves the least amount of power, though it has the quickest response time for fast load torque transients.
  • In Figure 2-11, the motor current takes long time to increase. This setting saves the most power, but has the slowest response to load torque transients.