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

2.4.3 Impact of Load Profile on Power Saving

This section explains how the nature of the load torque profile determines the power saving, as shown in Figure 2-14.

Figure 2-14 Power Saving as a Function of Load Torque
  • For a low value of ATQ_TRQ_MIN and ATQ_UL, the power saving at light loads is higher, but the power saving curve drops off to zero at a lower load torque.
  • A higher value of ATQ_TRQ_MIN and ATQ_UL result in only moderate power saving at light loads, but drops off at a higher load torque.

The choice of the power saving profile depends on the frequency and duty cycle of the peak load, as shown for three hypothetical load torque profiles and two power saving profiles in Figure 2-15.

Figure 2-15 Selecting Power Saving Profile
Table 2-4 Power Saving for Load Profiles A, B and C
Load Profile Peak Load Duty Power Saving With Plot I Power Saving With Plot II
A 10 % 72 % 57 %
B 40 % 48 % 48 %
C 60 % 32 % 42 %
  • As shown in Table 2-4, for load profile A, power saving plot I saves most power.
  • For the load profile B, both power saving plots save same amount of power.
  • For the load profile C, power saving plot II saves the most power.
  • Therefore, if the load profile is such that peak load duty is small, then choose low values of ATQ_TRQ_MIN and ATQ_UL.
  • If the peak load duty is high, choose higher values of ATQ_TRQ_MIN and ATQ_UL.