SLAU948 October 2024 MSPM0G3507
In Hall sensor Based FOC applications, the speed is determined from the rate of change of Hall Signal timings, At startup for the first few commutation cycles, the speed of the motor varies and the speed readings are updated at 60 degree intervals and not used for angle interpolation as the motor continues to accelerate. So for the first electrical cycle, the motor is ramped up and angle is incremented based on the Open loop profile determined by the openloop parameters. The speed loop with speed feedback is enabled after the completion of first electrical cycle and the angle is generated based on the Hall sensor based speed.
During openloop startup, the FOC algorithm accelerates the motor with a second order open loop ramp profile to increase the speed and the angle is computed based on the Openloop profile speed. At every Hall event, the angle is reset based on the programmed angle based on the sector derived from Hall signals.
By default, the open loop ramp up parameters are configured with a linear first order configuration with sluggish acceleration, which works for most of the motors. Usr can tune the second order openloop parameters using the MotorStartup2 parameters.