DRV10975ZPWPR datasheet(35/65 Pages) TI1

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Ktc

Lock detect

Kt_low

Kt_high

BEMF2 = Kt × Speed

BEMF1 = V

– I × Rm

Lock Detected If BEMF2 > V

DRV10975, DRV10975Z

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SLVSCP2E – JANUARY 2015 – REVISED MAY 2018

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Figure 30. Lock Detection 1

8.4.7.3 Lock2: Abnormal Kt

For any given motor, the integrated value of BEMF during half of an electrical cycle is constant. It is determined

by BEMF constant (Kt) (see Figure 31). It is true regardless of whether the motor is running fast or slow. This

constant value is continuously monitored by calculation and used as criteria to determine the motor lock

condition. It is referred to as Ktc.

Based on the Kt value programmed, create a range from Kt_low to Kt_high, if the Ktc goes beyond the range for

a certain period of time, tLCK_ETR, lock is detected. Kt_low and Kt_high are determined by KtLckThr[1:0] (see

Figure 32).

Figure 31. BEMF Integration

Figure 32. Abnormal Kt Lock Detect

8.4.7.4 Lock3 (Fault3): No Motor Fault

The phase U current is checked after transitioning from open loop to closed loop. If phase U current is not

greater than 140 mA then the motor is not connected as shown in Figure 33. This condition is treated and

reported as a fault.

DRV10975ZPWPR Datasheet(PDF) 35 Page - Texas Instruments