DRV8461SPWPR datasheet(42/117 Pages) TI

42 / 117 page

ATQ_CNT= k1×τ×ωIFS

(13)

where k1 is a constant at a given operating condition and IFS is the full-scale current (peak of the sinusoidal

current waveform) of the stepper driver.

Equation 13 defines the basic working principle of the auto-torque algorithm. The ATQ_CNT parameter can be

used to perform motor coil current regulation based on applied load torque on the stepper motor.

Figure 7-23 shows (ATQ_LRN + ATQ_CNT) measured as a function of load torque at 2.5A full-scale current for

a hybrid bipolar NEMA 24 stepper motor rated for 2.8A. ATQ_LRN does not change with load torque, whereas

ATQ_CNT changes linearly with load torque.

Load torque (Nm)

0.2

0.4

0.6

0.8

1.2

1.4

100

120

140

160

180

200

Figure 7-23. (ATQ_LRN + ATQ_CNT) vs. load torque

After auto-torque algorithm is enabled, the learning routine must be run to estimate the ATQ_LRN parameters.

The learning routine uses the linear relation between ATQ_LRN and motor current described in Equation 12.

The user has to select two current values at which learning will be performed, with no load torque applied on

the motor. These two current values are programmed by the ATQ_LRN_MIN_CURRENT and ATQ_LRN_STEP

registers.

• Initial current level = ATQ_LRN_MIN_CURRENT x 8

• Final current level = Initial current level + ATQ_LRN_STEP

The ATQ_LRN values at these two currents are saved in the ATQ_LRN_CONST1 and ATQ_LRN_CONST2

registers. These two registers are used to interpolate ATQ_LRN value for all other currents within the operating

range of the application.

Table 7-23 lists the registers associated with auto-torque learning routine.

Table 7-23. Registers for auto-torque learning routine

Description

ATQ_LRN_MIN_CURRENT[4:0]

Represents the initial current level for auto-torque learning routine.

DRV8461

SLOSE98 – DECEMBER 2022

www.ti.com

Submit Document Feedback

Product Folder Links: DRV8461

DRV8461SPWPR 数据表(PDF) 42 Page - Texas Instruments

DRV8461SPWPR 数据表(HTML) 42 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

数据表下载