DRV10975ZPWPR datasheet(31/65 Pages) TI1

31 / 65 page

Phase

Voltage

Phase

Current

Phase

BEMF

adv

Speed command

input

Speed command

after closed loop

accelerate buffer

Closed loop

accelerate settings

DRV10975, DRV10975Z

www.ti.com

SLVSCP2E – JANUARY 2015 – REVISED MAY 2018

Product Folder Links: DRV10975

Submit Documentation Feedback

Figure 25. Closed-Loop Accelerate

8.4.5.6 Control Coefficient

The DRV10975 continuously measures the motor current and uses this information to control the drive state of

the motor when operating in closed loop mode. In applications where noise makes it difficult to control the

commutation optimally, the CtrlCoef[1:0] can be used to attenuate the feedback used for closed loop control. The

loop will be less reactive to the noise on the feedback and provide for a smoother output.

8.4.5.7 Commutation Control Advance Angle

To achieve the best efficiency, it is often desirable to control the drive state of the motor so that the phase

current of the motor is aligned with the BEMF voltage of the motor.

To align the phase current of the motor with the BEMF voltage of the motor, consider the inductive effect of the

motor. The voltage applied to the motor should be applied in advance of the BEMF voltage of the motor (see

Figure 26). The DRV10975 provides configuration bits for controlling the time (tadv) between the driving voltage

and BEMF.

For motors with salient pole structures, aligning the motor BEMF voltage with the motor current may not achieve

the best efficiency. In these applications, the timing advance should be adjusted accordingly. Accomplish this by

operating the system at constant speed and load conditions and by adjusting the tadv until the minimum current is

achieved.

Figure 26. Advance Time (tadv) Definition

The DRV10975 has two options for adjusting the motor commutate advance time. When CtrlAdvMd = 0, mode 0

is selected. When CtrlAdvMd = 1, mode 1 is selected.

Mode 0: tadv is maintained to be a fixed time relative to the estimated BEMF zero cross as determined by

Equation 4.

tadv = tSETTING

(4)

Mode 1: tadv is maintained to be a variable time relative to the estimated BEMF zero cross as determined by

Equation 5.

tadv = tSETTING × (U-BEMF)/U.

where

•

U is the phase voltage amplitude

•

BEMF is phase BEMF amplitude

(5)

DRV10975ZPWPR Datasheet(PDF) 31 Page - Texas Instruments

DRV10975ZPWPR Datasheet(HTML) 31 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

Datasheet Download

Link URL