SLVSF30A October 2019 – October 2021 DRV10982-Q1
PRODUCTION DATA
If the motor is operating normally, the motor BEMF should always be less than the output amplitude. The DRV10982-Q1 device uses two methods of monitoring the BEMF in the system. The U phase current is monitored to maintain an estimate of BEMF based on the setting for Rm[6:0] {RmShift[2:0],RmValue[3:0]}. In addition, the BEMF is estimated based on the operation speed of the motor and the setting for Kt[6:0] {KtShift[2:0],KtValue[3:0]}. Figure 8-29 shows the method for using this information to detect a lock condition. If the motor BEMF is much higher than the output amplitude for a certain period of time, tLCK_ETR, it means the estimated speed is wrong, and the motor has gotten out of phase.