## Lab 3: SP-FC-FWR fed DC Motor speed control

### MATLAB Simulink LAB 3 file

Matlab v2018a or above is required to run this file. Click the link below to download the file.

#### Note - ملاحظة :

عند تنزيل الملف تاكد من ان يكون اسم الملف خالي من الفراغات و الاقواس وعلامة الناقص

• Uncompress 'LAB3_SPEED_CONTROL_DC_MOTOR_ACDC.zip' into the MATLAB document folder.
• Ensure to save the Lab 3 folder in the MATLAB folder and verify that the name of the folder does not contain invalid characters.

### Introduction

In this experiment, the speed of the DC-motor is controlled by using an open-loop voltage control via firing angle $\alpha$ of the SCR based SP-FC-FWR and a closed loop speed control via speed and current PI control. The purpose of this experiment is to implement a close-loop speed control of a DC-motor drive. The standard 5HP DC-motor is used where its parameters are given in the motor block of the experiment. The controller will be tested on a simulation model of the DC-motor.

### General questions

1) Explain two advantages of the Electric Drive System of the Electric motors?

2) A very important power electronic device is the Silicon Controlled Rectifier "SCR". Explain the construction, the function and the characteristics of the device.

• Run the simulation (with default configuration parameters) for the following two cases. Compare the observed values with calculated values. Save the plots and include them in your report.

• Case 1: Open-loop voltage control [Lab_3_SP_FC_FWR_DC_MOTOR_FOC_CASE1_v1.slx]
• Case 2: Closed-loop speed control [Lab_3_SP_FC_FWR_DC_MOTOR_FOC_CASE2_v1.slz]
• Adjust $\alpha$ to be between 0 and 179 degrees and observe the relationship with speed changes.
• Set the load torque for CASE 1 to be
Time=[0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45];
TL=[2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32];
• Set the reference speed for CASE 2 to be
Time=[0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45];
TL=[2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32];
SPEED=100*[1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1];

### Speed control of DC motor

• Explaint the controller of the motor in more details and elaborate on control strategy structure flow and investigate the advantages and disadvantages of the PI controller method.
• What is the power factor at rated speed? use the motor parameters and verify using the output mechanical power considering losses.
• When changing alpha from 30, 60, 90, 120 and 150 degrees, record the speed of the motor for each case and calculate the related armature voltage and current assuming constant load of 20 N.m.
• Change the reference speed to 800RPM by myliplying the speed vector by 8 as in

SPEED=SPEED*8;

Observe and compare the speed and torque ripple for both cases (100 rpm and 800 rpm), give an explanation for the differences.

### Conclusion

In yout own words, write the advantages and benefits for adapting a speed controller. What are the limitations when implementing a SP-FC-FWR for DC motor speed control?