Higher motor torque is required for acceleration and deceleration of a stepper motor compared to the torque at average and slew speeds (fmax). With a phase current setting adjusted for rapid acceleration and deceleration (steep ramps), the current is higher than needed while at constant speed. The motor will heat up faster than with the rated current applied. With a lower phase current, it is only possible to accelerate or decelerate with correspondingly longer ramp times.
Therefore, it is recommended to select different current settings for acceleration/deceleration and slewing:
– Continuous/slewing: Run current
– Acceleration/deceleration: Boost current
Phytron power stages are equipped with an input for activating the Boost function. As long as the input is activated, the actual current setting (run current or stop current) is increased by 30%. When the power stage is operated via the ServiceBus, the Boost current setting can be defined by the user. Thus, current enhancement can be perfectly adapted to the particular conditions and more energy than necessary is not fed to the motor – the stepper motor remains cooler.