Modeling of hybrid stepper motor (HSM) using Simulink

Hi all,

I am trying to build a Simulink model for HSM, using the math model in photo p1. This model is the same seen in Matlab documentation for the stepper motor in Simscape electrical, and my final Simulink model is shown in the photos p2,p3,p4, and p5, and the HSM parameters are:

R=0.9; % Resistance, Ohm
L=3.5e-3; % Inductance, H
M=0; % Matual Inductance, H
k_t=0.75; % Torque constant, N.m/A
k_d=0.15; % Max detent torque, N.m
T_h=3 % motor holding torque at 4A phase current N.m
B=0.01; % Viscous friction Coiff., N.m.s/rad
J_M=720e-9; % Motor Inertia
J_L=0.3; % Load Inertia
m=2; % # of phases
Step=1.8; % Step angle, 1.8 deg
Step_rev=360/Step; % # of steps per Rev.
Nr=Step_rev/m; % # of rotor teeth
p=Nr/2; % # of poles pairs

However, my model has an issue in the step response, and the output motor torque as the response in p6 shows.

1. The step angle is 0.9 deg (half the 1.8 deg), and
2. the motor holding torque does not exceed 0.2 N.m.
3. At the beginning, the motor moves a bit backward then moves forward (the requested direction).

I have used the p (# of poles), in my model instead of Nr (rotor teeth number), and solved point 1, as photo p7 shows, but points 2, and 3 are still an issue.

I have applied these parameters to the stepper motor block in Simscape electrical, and got the required holding torque (3 N.m), and the step angle, as photos p8 and p9