# Build a permanent magnet servo motor using simulink and a four

Consider a permanent magnet dc servo motor with the following parameters: Tem(rated) = 10Nm

Rated Speed in rpm Nrpm = 3700

kT = 0.5Nm/A

kE = 0.5V/rad/s

Ra = 0.37Ω

La/Ra = 4.05 × 10−3 s

Jeq = 0.0079kg-m2

The servo motor is driven by a full-bridge four-quadrant dc-dc converter operating from a 200V dc bus. The motor is delivering a torque of 5Nm at a speed of 1500rpm. The switching frequency is 20kHz.

1. Build the above dc motor and power electronic converter in Simulink. Using the simulation model, determine the peak-peak ripple in the armature current for the above operating condition in open-loop?

2. Design the current loop for a crossover frequency of 1kHz and the speed controller for a crossover frequency of 100Hz.

3. Build the closed loop model in Simulink. In the model, For a step increase in load torque from 5Nm to 10Nm,  with the speed reference at rated value, plot the response of the system speed and armature current .