For example, ceiling fan motors have higher inertia due to the fan blades and can coast for long time before
stopping.
Step 1: Enable ISD [ISD_EN]
Step 2: Enable Motor ISD Resynchronize [RESYNC_EN]
Note
Follow the below recommendations if the motor fails to startup.
1. Increase the Motor Stationary BEMF Threshold [STAT_DETECT_THR].
2. Increase the Motor Stationary Persistence Time [ISD_STOP_TIME].
3. Increase the Motor Run Persistence Time [ISD_RUN_TIME].
4. Increase the Minimum speed threshold to resynchronize to closed loop
4.3.3 Unidirectional Motor Drive Detecting Backward Spin
For applications that require spinning the motor in a specific direction, it is important to know if the motor is
coasting or spinning in the direction opposite to the intended direction of spin. MCF8316A reverse drive function
acts to reverse decelerate the motor through zero speed and to accelerate after changing direction until it
transitions into closed loop as shown in Figure 4-7.
Reverse Deceleration
Open Loop
Handoff to close loop
Open loop
Close loop
Speed
Time
Handoff to open loop
Figure 4-7. Reverse Drive Function
MCF8316A provides an option to apply brakes and stop the motor while the motor is coasting or spinning in
reverse direction and then accelerate into closed loop after changing the direction.
In applications such as ceiling fans and pumps, it is required to spin the motor in specific direction for desired
results. For such applications, it is recommended to follow the below recommendations.
Step 1: Enable ISD [ISD_EN]
Step 2: Enable Motor ISD Reverse drive [RVS_DR_EN]
Step 3: Enable reverse resynchronization [RESYNC_EN]
Step 4: Enable Active brake reverse drive [ACTIVE_BRAKE_REV_DRV_EN]
Step 5: Enter the Kp coefficient [ACTIVE_BRAKE_KP] and Ki coefficient [ACTIVE_BRAKE_KI] for Active
braking loop. We recommend to start with Kp coefficient [ACTIVE_BRAKE_KP] as 700 and Ki coefficient
[ACTIVE_BRAKE_KI] as 100.
Basic Controls www.ti.com
16 MCF8316A Tuning Guide SLLU335A – AUGUST 2021 – REVISED JANUARY 2022
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