List of figures

AN4158

4/34

DocID023635 Rev 2

List of figures

Figure 1.

Basic two-phase bipolar stepper motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Figure 2.

Torque during a step change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Figure 3.

Magnetic field directions in full step and half step driving modes . . . . . . . . . . . . . . . . . . . . . 8

Figure 4.

Microstepping phase currents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Figure 5.

full step driving versus microstepping motor torque . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Figure 6.

Current control system for each motor phase. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Figure 7.

Motor phase electrical model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Figure 8.

Constant off-time control sequence (low-side recirculation) . . . . . . . . . . . . . . . . . . . . . . . . 14

Figure 9.

Peak current control stability conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 10.

Back electromotive force limiting the slow decay effectiveness . . . . . . . . . . . . . . . . . . . . . 16

Figure 11.

Constant off-time control using fast decay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Figure 12.

Minimum on-time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Figure 13.

Peak current control unstable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Figure 14.

Peak current control in microstepping (slow decay only) . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Figure 15.

Peak and average current and stator magnetic field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Figure 16.

Minimum on-time threshold and on-time limit relation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 17.

Decay selection according to on-time duration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 18.

Decay strategy change due to second on-time threshold violation . . . . . . . . . . . . . . . . . . 23

Figure 19.

Fast decay time regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Figure 20.

Current control at rising step (reference current increased) . . . . . . . . . . . . . . . . . . . . . . . . 24

Figure 21.

Current control at falling step (reference current decreased) . . . . . . . . . . . . . . . . . . . . . . . 25

Figure 22.

Predictive current control basic principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Figure 23.

Off-time automatic adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Figure 24.

On-time measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Figure 25.

TOFF_FAST and TON_MIN parameter relations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Figure 26.

Falling step - 8 microstep example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Figure 27.

High FAST_STEP value example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Figure 28.

Low FAST_STEP value example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32