Unipolar Stepper Motor Averaged Mode

This model shows the Unipolar Stepper Motor simulating in Stepping and Averaged simulation modes. The purpose of Averaged mode is faster simulation for any loads that do not cause slip. To avoid incorrect interpretation of results, the stepper motor has an approximate detection of slip which can be set to generate a warning or an error.

Use the two callback blocks to switch between simulation modes to verify results. If you increase load inertia (workspace parameter J) to 0.05 kg*m^2 or load damping (workspace parameter L) to 2 N*m/s, both simulation modes will indicate slip. Once slip occurs, results will diverge as the Averaged mode assumes the stepper speed controller detects slip and adjusts the demand to maintain synchronous operation.

Model

Simulation Results from Simscape Logging

The plot below shows the shaft angle and shaft speed of the stepper motor in full stepping mode. Oscillations in the shaft speed occur as the shaft settles into the current step. In averaged mode, the angle and speed are smooth as individual steps are not simulated.

The plot below compares the shaft angle and shaft speed of the stepper motor in stepped and averaged mode. Oscillations in the shaft speed are seen in stepped mode as the individual steps are simulated.