DRV10987 Datasheet, PDF (40/69 Pages) Texas Instruments – DRV10987 12- to 24-V, Three-Phase, Sensorless BLDC Motor Driver

DRV10987
SLVSE89 – AUGUST 2017
Motor phase
driving voltage
FGOLsel = 00
FGOLsel = 01
Open loop
Closed loop
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Motor phase
driving voltage
Open loop
Closed loop
Open loop
Closed loop
FGOLsel = 10
Start-up after power on or wakeup
from sleep or standby mode
Rest of the startups
Figure 39. FG Behavior During Open Loop
8.4.12 Diagnostics and Visibility
The DRV10987 device offers extensive visibility into the motor system operation conditions stored in internal
registers. This information can be monitored through the I²C interface. Information can be monitored relating to
the device status, motor speed, supply voltage, speed command, motor phase-voltage amplitude, fault status,
and others. The data is updated on the fly.
8.4.12.1 Motor-Status Readback
The motor FaultReg register provides information on overtemperature (OverTemp), overcurrent (OverCurr), and
locked rotor (Lock0–Lock5).
8.4.12.2 Motor-Speed Readback
The motor operation speed is automatically updated in register MotorSpeed while the motor is spinning. The
value is determined by the period for calculated BEMF zero crossings on phase U. The electrical speed of the
motor is denoted as Velocity (Hz) and is calculated as shown in Equation 9.
Velocity (Hz) = {MotorSpeed} / 10
(9)
As an example consider the following:
MotorSpeed = 0x01FF;
Velocity = 512 (0x01FF) / 10 = 51 Hz
51 ^ecycles u ^{1 mechcycle} u 60 ^{sec ond} 1530 RPM
For a 4-pole motor, this translates to: ^{sec ond 2 ecycle}
minute
40
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