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

DRV10987
SLVSE89 – AUGUST 2017
60 degrees
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±
V
+
U
+
W
±
Figure 14. Initial Speed Detect Function
If the UW comparator output is lagging the UV comparator by 60°, the motor is spinning forward. If the UW
comparator output is leading the UV comparator by 60°, the motor is spinning in reverse.
The motor speed is determined by measuring the time between two rising edges of either of the comparators.
If neither of the comparator outputs toggles for a given amount of time, the condition is defined as stationary. The
amount of time can be programmed by setting the register bits ISDThr[1:0].
8.4.3.2 Motor Resynchronization
The resynchronize function works when the ISD function is enabled and determines that the initial state of the
motor is spinning in the forward direction. The speed and position information measured during ISD are used to
initialize the drive state of the DRV10987 device, which can transition directly into the closed-loop running state
without needing to stop the motor.
8.4.3.3 Reverse Drive
The ISD function measures the initial speed and the initial position; the DRV10987 reverse drive function acts to
reverse accelerate the motor through zero speed and to continue accelerating until the closed loop threshold is
reached (see Figure 15). If the reverse speed is greater than the threshold configured in RvsDrThr[1:0], then the
DRV10987 device waits until the motor coasts to a speed that is less than the threshold before driving the motor
to reverse accelerate.
Speed
Open loop
Closed loop
Op2ClsThr
Time
Coasting
Reverse Drive
RevDrThr
Figure 15. Reverse Drive Function
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