SLAU927B June 2024 – November 2024 MSPM0G3507
The Initial Speed Detection (ISD) function is used to identify the initial condition of the motor. It is important to know the initial condition of the motor for reliable resynchronization. Motor resynchronization failures can occur when the device attempts to start the motor while the motor is coasting or spinning in the direction opposite to the intended direction of spin. Motors can coast in applications that require frequent motor starts and stops, if the motor is being forced externally, or if there is a power interruption. Motors can spin in the direction opposite to the intended direction of spin if motor phase wires are connected to OUTA, OUTB, and OUTC in wrong sequence or when the wrong direction command is issued. Motors with higher inertia coast for a longer period of time. Enable ISD in applications that require frequent motor starts and stops, and use higher inertia motors.
For example, ceiling fan motors have higher inertia due to the fan blades and can coast for a long time before stopping.
Step 1: Enable ISD [ISD_EN]
Step 2: Enable Motor ISD Resynchronize [RESYNC_EN]