DRV10987 Datasheet, PDF (36/69 Pages) Texas Instruments – DRV10987 12- to 24-V, Three-Phase, Sensorless BLDC Motor Driver

DRV10987
SLVSE89 – AUGUST 2017
www.ti.com
Figure 32. BEMF Integration
Ktc
Kt_high
Kt
Kt_low
Lock detect
Figure 33. Abnormal-Kt Lock Detect
8.4.8.4 Lock3 (Fault3): No-Motor Fault
The phase U current is checked after transitioning from open loop to closed loop. If the phase U current is not
greater than 140 mA then the motor is not connected as shown in Figure 34. This condition is treated and
reported as a fault.
DRV10987
M
Figure 34. No-Motor Error
8.4.8.5 Lock4: Open-Loop Motor-Stuck Lock
Lock4 is used to detect locked-motor conditions while the motor start sequence is in open loop.
For a successful startup, motor speed should be equal to the open-to-closed-loop handoff threshold when the
motor is transitioning into closed loop. However, if the motor is locked, the motor speed is not able to match the
open-loop drive rate.
If the motor BEMF is not detected for one electrical cycle after the open-loop drive rate exceeds the threshold,
then the open loop was unsuccessful as a result of a locked-rotor condition.
8.4.8.6 Lock5: Closed-Loop Motor-Stuck Lock
If the motor suddenly becomes locked, motor speed and Ktc are not able to be refreshed because the BEMF
zero cross of the motor may not appear after the lock. In this condition, lock can also be detected by the
following scheme: if the current commutation period is 2× longer than the previous period.
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