Patent ID: 8829844

Claim:
A method for operating a stepper motor of a pumping system during a fluid intake cycle, comprising: measuring available torque of the stepper motor across a range of motor velocities within which the stepper motor will operate during the intake cycle; calculating a maximum acceleration rate for each of a plurality of motor velocities in the range of motor velocities based on the available torque of the stepper motor measured at that motor velocity; generating an intake velocity profile based on the maximum acceleration rates calculated for the plurality of motor velocities; and accelerating the stepper motor during the intake cycle in accordance with the generated intake velocity profile; wherein accelerating the stepper motor during the intake cycle in accordance with the generated intake velocity profile includes: initially accelerating the stepper motor at a constant acceleration rate until the stepper motor reaches a first motor velocity; and after the stepper motor reaches the first motor velocity, accelerating the stepper motor at a decreasing acceleration rate to bring the stepper motor to a desired terminal velocity; wherein the intake velocity profile is a first intake velocity profile and further comprising: operating the stepper motor in accordance with a second intake velocity profile that causes the stepper motor to run at a constant acceleration rate until the stepper motor reaches a desired terminal velocity, followed by constant deceleration rate after the stepper motor operates at the desired terminal velocity for a given period; determining whether the desired terminal velocity exceeds a threshold velocity; and switching control of the stepper motor from the second intake velocity profile to the first intake velocity profile when the desired terminal velocity exceeds the threshold velocity.