Catch spin method for permanent magnet synchronous motor with sensorless field oriented control

A motor control actuator configured to drive a permanent magnet synchronous motor (PMSM) with sensorless Field Oriented Control (FOC), the motor control actuator comprising:

• a sampling circuit configured to measure a back electro motive force (BEMF) of the PMSM, while the PMSM rotates, and generate a measurement signal based on the measured BEMF;
• a phase-locked loop (PLL) configured to receive the measurement signal and extract an amplitude and an angle of the BEMF from the measurement signal;
• and
• a motor controller configured to generate a first set of two phase alternating current (AC) voltage components based on an estimated rotor angle, generate a second set of two phase AC voltage components based on the amplitude and the angle, and generate control signals for driving the PMSM based on the first set of two phase AC voltage components,
• wherein the motor controller is configured to perform a catch spin sequence for restarting the PMSM while rotating, the catch spin sequence including a synchronizing period followed by a closed loop control period,
• wherein, during the synchronizing period, the motor controller is configured to estimate a first rotor angle based on the second set of two phase AC voltage components, wherein the first rotor angle is used by the motor controller to synchronize to a rotor angle of the PMSM, and
• wherein, during the closed loop control period, the motor controller is configured to estimate a second rotor angle based on the first rotor angle and based on the first set of two phase AC voltage components, wherein the second rotor angle is used by the motor controller to synchronize to the rotor angle of the PMSM.