DRV10975_15 Datasheet, PDF (16/57 Pages) Texas Instruments – DRV10975 12-V, Three-Phase, Sensorless BLDC Motor Driver

DRV10975
SLVSCP2 – JANUARY 2015
Kt_PH (mV/Hz)
4.18
4.88
5.57
6.27
6.97
7.66
8.36
9.06
9.76
10.4
11.1
12.5
13.9
15.3
16.7
18.1
19.5
20.9
22.3
Table 3. Motor Velocity Constant Look-Up Table (continued)
Kt[6:0]
0000110
0000111
001000
0001001
0001010
0001011
0001100
0001101
0001110
0001111
0011000
0011001
0011010
0011011
0011100
0011101
0011110
0011111
0101000
HEX
06
07
08
09
0A
0B
0C
0D
0E
0F
18
19
1A
1B
1C
1D
1E
1F
28
Kt_PH (mV/Hz)
41.8
44.6
50.2
55.7
61.3
66.9
72.5
78.0
83.6
89.2
100
111
122
133
145
156
167
178
200
Kt [6:0]
0101111
0111000
0111001
0111010
0111011
0111100
0111101
0111110
0111111
1001000
1001001
1001010
1001011
1001100
1001101
1001110
1001111
1011000
1011001
HEX
2F
38
39
3A
3B
3C
3D
3E
3F
48
49
4A
4B
4C
4D
4E
4F
58
59
Kt_PH (mV/Hz)
356
401
446
490
535
580
624
669
713
803
892
981
1070
1160
1240
1330
Kt [6:0]
1101000
1101001
1101010
1101011
1101100
1101101
1101110
1101111
1111000
1111001
1111010
1111011
1111100
1111101
1111110
1111111
www.ti.com
HEX
68
69
6A
6B
6C
6D
6E
6F
78
79
7A
7B
7C
7D
7E
7F
9.4.2 Starting the Motor under Different Initial Conditions
The motor can be in one of three states when the DRV10975 attempts to begin the start-up process. The motor
may be stationary, or spinning in the forward or reverse directions. The DRV10975 includes a number of features
to allow for reliable motor start under all of these conditions. Figure 8 shows the motor start-up flow for each of
the three initial motor states.
9.4.2.1 Case 1 – Motor is Stationary
If the motor is stationary, the commutation logic must be initialized to be in phase with the position of the motor.
The DRV10975 provides for two options to initialize the commutation logic to the motor position. Initial position
detect (IPD) determines the position of the motor based on the deterministic inductance variation, which is often
present in BLDC motors. The Align and Go technique forces the motor into alignment by applying a voltage
across a particular motor phase to force the motor to rotate in alignment with this phase. The following sections
explain how to configure these techniques for use in the designer's system.
9.4.2.2 Case 2 – Motor is Spinning in the Forward Direction
If the motor is spinning forward with enough velocity, the DRV10975 may be configured to go directly into closed
loop. By resynchronizing to the spinning motor, the user achieves the fastest possible start-up time for this initial
condition.
9.4.2.3 Case 3 – Motor is Spinning in the Reverse Direction
If the motor is spinning in the reverse direction, the DRV10975 provides several methods to convert it back to
forward direction.
One method, reverse drive, allows the motor to be driven so that it accelerates through zero velocity. The motor
achieves the shortest possible spin-up time in systems where the motor is spinning in the reverse direction.
If this feature is not selected, then the DRV10975 may be configured to either wait for the motor to stop spinning
or brake the motor. After the motor has stopped spinning, the motor start-up sequence proceeds as it would for a
motor which is stationary.
Take care when using the feature reverse drive or brake to ensure that the current is limited to an acceptable
level and that the supply voltage does not surge as a result of energy being returned to the power supply.
16
Submit Documentation Feedback
Product Folder Links: DRV10975
Copyright © 2015, Texas Instruments Incorporated