DRV10987 Datasheet, PDF (34/69 Pages) Texas Instruments – DRV10987 12- to 24-V, Three-Phase, Sensorless BLDC Motor Driver

DRV10987
SLVSE89 – AUGUST 2017
www.ti.com
When the acceleration current limit is active, it does not stop the motor from spinning nor does it trigger a fault.
The functionality of the acceleration current limit is only available in closed-loop control.
Rm
U_LIMIT
I_LIMIT
M BEMF = Kt ´ speed
Figure 28. Acceleration Current Limit
V_{U_LIMIT} = I_LIMIT × Rm + Speed × Kt
(8)
8.4.8 Lock Detect and Fault Handling
The DRV10987 device provides several options for determining if the motor becomes locked as a result of some
external torque. Five lock-detect schemes work together to ensure the lock condition is detected quickly and
reliably. Figure 29 shows the logic which integrates the various lock-detect schemes. When a lock condition is
detected, the DRV10987 device takes action to prevent continuously driving the motor in order to prevent
damage to the system or the motor.
In addition to detecting if there is a locked motor condition, the DRV10987 device also identifies and takes action
if there is no motor connected to the system.
Each of the five lock-detect schemes and the no-motor detection can be disabled by their respective register bits,
LockEn[5:0].
When a lock condition is detected, the FaultReg register provides an indication of which of the six different
conditions was detected on Lock5 to Lock0. These bits are reset when the motor restarts. The bits in the
FaultReg register are set even if the lock detect scheme is disabled.
The DRV10987 device reacts to either locked-rotor or no-motor-connected conditions by putting the output
drivers into a high-impedance state. To prevent the energy in the motor from pumping the supply voltage, the
DRV10987 device incorporates an anti-voltage-surge (AVS) process whenever the output stages transition into
the high-impedance state. The AVS function is described in Anti-Voltage Surge Function. After entering the high-
impedance state as a result of a fault condition, the system tries to restart after t_{LOCK_OFF}.
LockEn (0, 1, 2, 3, 4, 5)
Lock detection current limit
Speed abnormal
BEMF abnormal
No motor fault
Tri-state
Or
and restart
logic
Open loop stuck
Closed loop stuck
Set
Register: ^Reset
FaultReg[5:0]
Figure 29. Lock Detect and Fault Diagnose
34
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