JAJSEE9E January 2015 – May 2018 DRV10975
PRODUCTION DATA.
If motor is operating normally, the motor BEMF should always be less than output amplitude. The DRV10975 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]. In addition, the BEMF is estimated based on the operation speed of the motor and the setting for Kt[6:0]. Figure 30 shows the method for using this information to detect a lock condition. If motor BEMF is much higher than 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.