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ARID ZONE JOURNAL OF ENGINEERING, TECHNOLOGY & 

ENVIRONMENT 

 

ORIGINAL RESEARCH ARTICLE  

IMPLEMENTATION OF THYRISTOR BASED CONTROL OF 

SEPARATELY EXCITED DC MOTOR DRIVEN BY SINGLE-PHASE 

SEMI-CONVERTER 

G. C. Diyoke1*, C. A. Okeke1 and C. Ezugwu2 
1Department of Electrical and Electronic Engineering, Michael Okpara University of Agriculture, Umudike, Abia State, 

Nigeria. 
2Department of Electrical and Electronic Engineering Technology, Federal Polytechnic, Nasarawa, Nasarawa State, 

Nigeria. 
*Corresponding author’s email address: geraldiyoke@mouau.edu.ng 

ARTICLE INFORMATION ABSTRACT 
This paper presents the implementation of thyristor-based control for a separately 

excited DC motor using a single-phase semi-converter. The study focuses on the design, 

operation, and performance analysis of the system, highlighting its ability to efficiently 

control the motor's speed and torque. The semi-converter, consisting of thyristors, 

provides variable DC voltage to the motor by controlling the firing angle, enabling precise 

regulation of motor parameters. Key aspects, such as circuit design, firing angle control, 

and power quality considerations, are discussed in detail. Computer aided simulation 

results demonstrate the effectiveness of the proposed system in achieving smooth and 

reliable motor control with improved energy efficiency. The findings underline the 

applicability of thyristor-based control in industrial and automation applications, offering 

a cost-effective solution for DC motor drives. It is observed that the method of voltage 

control shows that a rated voltage of 200 V, the rated speed of 1500 RPM and torque 

of 10.5 N-m cannot be exceeded. The method of field flux control shows that a rated 

voltage, the rated speed can be exceeded to reach 208 V and 3000 RPM respectively 

while the rated torque cannot be reached.  

Submitted: 5th September 2024     

Revised: 24th December 2024        

Accepted: 3rd February 2025      

Keywords: 

Semi-converter 

Dc motor 

Armature voltage 

Field current 

Speed 

Torque 

 

© 2025 Faculty of Engineering, University of Maiduguri, Nigeria. All rights reserved. 

1.0 Introduction 

In order to control the dc motor speed (Poomima et al., 2006), the thyristor semi-converter provides a 

variable output voltage. A direct current (DC) motor is a machine that converts DC electrical energy into 

rotating mechanical energy and are rated in horsepower (Onah et al., 2022 and Asadi et al., 2019). Due to the 

simplicity, high power conversion efficiency, low cost of operation of the system, reliability, controllability 

(Perelmuter 2012; Nguyen et al., 2019; Rashag 2019; Sami et al., 2021 and Duby et al., 2022) and maintainability, 

it is widely used in industrial and domestic applications as reported by kandpal et al., (2015); Hareb et al., 

(2021); Virendra et al., (2013) and Sharma et al., (2016). Some of the applications are in dc drive systems for 

paper production, photographic film manufacturing, machine tools, traction, crude oil pipelines, variable-speed 

drives for woodworking machines, rolling mills, and traction drives as presented by El-Kholy et al., (2004) and 

Tiwari et al., (2019), adjustable-speed drive systems for textiles, renewable energy systems for wind turbine, 

solar tracking, home applications for vacuum cleaner, washing machines, electric razors, blender, food 

processor. Another vital merit of the system is that it requires no extra circuitry for commutation process 

(Hughes 2006 and Krishnan 2001). Separately excited dc motors are often used in applications needing precise 

control of speed and torque over a wide range (Hassan et al., 2023; and Hameed and Ali 2016). The report 

by Amed et al. (2023) detailed the study of microcomputer-based torque control of dc separately excited 

motor using the proportional integral (PI) controller. Based on the performance indices, semi-converter 

performs better than full-converter systems. 

AZOJETE March 2025. Vol.21(1):145-156 

Published by the Faculty of Engineering, University of Maiduguri, Maiduguri, Nigeria. 

Print ISSN: 1596-2490, Electronic ISSN: 2545-5818 

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A rectifier is a type of power electronics converter that performs a conversion of electrical energy from one 

form to another (Namdeo et al., 2014). Semi-converter uses both thyristors and diodes for power conversion. 

It is simple to control, economical based on cost and more reliable during the operation. It operates by 

controlling the conduction angle of the thyristors, which regulates the amount of power transferred. The 

armature current in general is non-continuous at high values of the firing angle, high motor speed and low 

values of machine torque. An external armature circuit choke can be applied to promote continuous armature 

current operation. Rectifiers play a vital role in various industrial, commercial and renewable energy 

applications, offering flexibility and efficiency in power conversion processes. Some of its applications are as 

follows: motor drives, dc power supply, heating systems, renewable energy, HVDC transmission, battery 

charging systems, etc. Speed control in a DC separated excited motor can be achieved through various 

methods, each offering different advantages and suitability depending on the application requirements. Here 

are some common methods of speed control for DC separated excited motors: (1) armature voltage control: 

this achieved by varying the voltage applied (Duby 2009 and Saini et al., 2020) to the armature winding of the 

motor, thereby the motor speed can be controlled; (2) field flux control: this is realized by adjusting the field 

winding excitation, the magnetic flux within the motor can be varied, affecting its speed-torque characteristics.  

2. Materials and Method 

2.1 Single-phase Semi-Converter Configuration and Operation 

In Figure 1, a semi-converter circuit configuration fed with separately excited dc motor is developed. The 

power circuit consists of two controlled power thyristors T1 and T4, two power diodes D2 and D3, and one 

freewheeling diode DF. The ac source Vs is given by 𝑉𝑚𝑠𝑖𝑛𝜔𝑡, where Vm is the amplitude and ω is the source 

frequency in rad/sec. The two similar power circuit are responsible for armature voltage and current and field 

voltage and current respectively. The load is modeled as series combination of a dc motor with Ra and La as 

armature resistance and inductance and E as the induced emf applied for variable-speed motor drives. 

 

Figure 1: Semi-converter-fed separately excited dc motor configuration 

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Figure 2: Waveforms of Semi-converter mode of operation. 

Operation of the semi-converter circuit depicted in Figure 2; and Figure 2(a) depicts the supply voltage, dc 

motor EMF and gate pulses plots against the 𝜔𝑡 (Radians). The output and armature currents are shown in 

Figure 2(b), under continuous current mode of operation. Waveforms shown in Figure 2(c and d) are analyzed 

as follows: 

At interval α ≤ 𝜔𝑡 ≤ 𝜋, the gate signal ig1 is high, T1 and D2 conduct current in this interval. That is, output 

voltage 𝑉𝑜 = 𝑉𝑚𝑠𝑖𝑛𝜔𝑡; voltage drop across thyristor T4, 𝑉𝑇4 = 0; and voltage drop across thyristor T1, 𝑉𝑇1 =
−𝑉𝑚𝑠𝑖𝑛𝜔𝑡; This operation puts the thyristor and diode (T4 and D3) into a reverse biased mode.  Also, at the 

interval α+𝜋 ≤ 𝜔𝑡 > 2𝜋, the gate signals ig4 is high, T4 and D3 conduct current during this operation. In both 

intervals the output current io > 0. For, 𝑉𝑜 = 𝑉𝑚𝑠𝑖𝑛𝜔𝑡; and 𝑉4 = −𝑉𝑚𝑠𝑖𝑛𝜔𝑡; D3 conducting current. However, 

the system performance can be further obtained through the Fourier analysis and some notations used in this 

work are Va is armature voltage, Ia is armature current, Ra is armature resistance, La is armature inductance, 

Vm is peak voltage, TF is field torque, Td is developed torque, PF is the field power, Pd is the developed torque, 

IF is the field current, α is the firing angle for armature voltage, 𝛼𝐹 is the field circuit firing angle. 

In Fourier series, the output voltage 𝑣𝑜(𝜔𝑡) as depicted in Figure 2(c) for continuous current operation is 

expressed as: 

𝑣𝑜(𝜔𝑡) = 𝑉𝑎 + ∑(𝑉𝑎𝑛𝑐𝑜𝑠𝑛𝜔𝑡 + 𝑉𝑏𝑛𝑠𝑖𝑛𝑛𝜔𝑡)

∞

𝑛=1

                                                                                                           1 

Referring to Figure 2(c), we can derive the formular for computing the armature load voltage Va  

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𝑉𝑎 =
1

𝜋
[∫ 𝑣𝑜𝑑(𝜔𝑡)

𝜋

𝛼

]    =  
𝑉𝑚

𝜋
(𝑐𝑜𝑠𝛼 + 1)                                                                                                                       2 

The rectifier output voltage as a function of 𝜔t is given by  

𝑣𝑜(𝜔𝑡) =
𝑉𝑚

𝜋
{(𝑐𝑜𝑠𝛼 + 1)

+ ∑ ([
𝑐𝑜𝑠𝛼(𝑛 + 1) + 1

(𝑛 + 1)
−

𝑐𝑜𝑠𝛼(𝑛 − 1) + 1

(𝑛 − 1)
] 𝑐𝑜𝑠𝑛𝜔𝑡

∞

𝑛=2,4,6,..

+ [
𝑠𝑖𝑛𝛼(𝑛 + 1)

(𝑛 + 1)
−

𝑠𝑖𝑛𝛼(𝑛 − 1)

(𝑛 − 1)
] 𝑠𝑖𝑛𝑛𝜔𝑡) }                                                                                    3 

The nth harmonic amplitude Cn is given as in equation (5) 

𝐶𝑛 = 𝑉𝑛 = √𝑉𝑎𝑛
2 + 𝑉𝑏𝑛

2                                                                                                                                                       4 

𝑉𝑛 =
2𝑉𝑚

𝜋(𝑛2 − 1)
[𝑐𝑜𝑠2𝛼 − 𝑛2𝑐𝑜𝑠2𝛼 + 2 cos(𝑛𝛼) 𝑐𝑜𝑠𝛼 + 𝑛2 + 2nsin(𝑛𝛼) 𝑠𝑖𝑛𝛼 + 1]

1
2    (5) 

While the phase magnitude is developed as 

∅𝑛 = tan−1 (
𝑏𝑛

𝑎𝑛
)                                                                                                                                                                  6 

∅𝑛 = tan−1 (
𝑛 − 1(𝑠𝑖𝑛𝛼(𝑛 + 1)) − 𝑛 + 1(𝑠𝑖𝑛𝛼(𝑛 − 1))

𝑛 − 1(𝑐𝑜𝑠𝛼(𝑛 + 1) + 1) − 𝑛 + 1(𝑐𝑜𝑠𝛼(𝑛 − 1) + 1)
)                                                                     7 

Where, 𝑍𝑛 = √𝑅𝑎
2 + (𝑛𝜔𝐿𝑎)2            and    𝜃𝑛 = tan−1 (

𝑛𝜔𝐿𝑎

𝑅𝑎
)    

The root mean square voltage can be computed by equation (8) 

𝑉𝑜𝑟𝑚𝑠 =
1

𝜋
[∫ 𝑣𝑜

2𝑑(𝜔𝑡)

𝜋

𝛼

]    =
𝑉𝑚

√2𝜋
[𝜋 − 𝛼 +

𝑠𝑖𝑛2𝛼

2
]

1
2

                                                                                                 8 

The average load or armature current 𝐼𝑎 then becomes: 

𝐼𝑎 =
𝑉𝑎 − 𝐸

𝑅𝑎
                                                                                                                                                                           9 

In Fourier series, the output current 𝑖𝑜(𝜔𝑡) as depicted in Figure 2(b) for continuous current operation is 

expressed as: 

𝑖𝑜(𝜔𝑡) =

𝑉𝑚
𝜋

(𝑐𝑜𝑠𝛼 + 1) − 𝐸

𝑅𝑎
  + ∑

1

𝑍𝑛

(𝑉𝑎𝑛cos (𝑛𝜔𝑡 − 𝜃𝑛) + 𝑉𝑏𝑛sin (𝑛𝜔𝑡 − 𝜃𝑛))

∞

𝑛=2,4,6,..

                              10 

The rms load current, Iarms is calculated using 

𝐼𝑎𝑟𝑚𝑠 = √𝐼𝑎
2 + ∑ 𝐼𝑟𝑛

2

∞

𝑛=2,4,6…

                                                                                                                                             11 

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Where, the nth rms ripple load current Irn is given as 

|𝐼𝑟𝑛| =
𝑉𝑛 √2⁄

√𝑅𝑎
2 + (𝑛𝜔𝐿𝑎)2

                                                                                                                                                  12 

The power delivered to the dc motor is computed using  

𝑃𝑑 = 𝐼𝑎𝑟𝑚𝑠
2 𝑅𝑎 + 𝐼𝑎𝐸                                                                                                                                                         13 

The supply power factor can be computed using the formula 

𝑝𝑓 =
𝐼𝑎𝑟𝑚𝑠

2 𝑅𝑎 + 𝐼𝑎𝐸

𝑉𝑠𝐼𝑎𝑟𝑚𝑠
                                                                                                                                                        14 

The form factor for separately excited dc motor armature current is defined as  

𝐹𝑜𝑟𝑚 𝑓𝑎𝑐𝑡𝑜𝑟, 𝐹𝐹 =
𝐼𝑎𝑟𝑚𝑠

𝐼𝑎
=

𝑅𝑎𝐼𝑎𝑟𝑚𝑠

𝑉𝑚
𝜋

(𝑐𝑜𝑠𝛼 + 1) − 𝐸
                                                                                                    15 

2.2 Separately excited dc motor operation and analysis 

In separately excited dc motor, the field and armature voltages can be controlled independent of each other. 

Therefore, when the electric field current (IF) flows in the field winding of the machine, then magnetic field is 

created which exerts a magnetic force on the rotor or armature coils carrying the current (Ia), causing the 

rotor to rotate. During this process a back EMF (E) is induced in the armature winding as it rotates. 

The basic equations of the dc motor for steady-state operation can be generated as follows [1]: 

𝑉𝑎 = 𝐸 + 𝐼𝑎𝑅𝑎  = 𝐾𝜔𝑚 + 𝐼𝑎𝑅𝑎                                                                                                                                      16 

Generated EMF, speed, flux and number of conductors in the armature is related as: 

𝐸 =
𝑝𝑍

𝑐
𝜙 (

2𝜋𝑁

60
) = 𝑘𝜙𝜔𝑚 = 𝑘𝐼𝐹𝜔𝑚 = 𝐾𝜔𝑚                                                                                                          17 

The field current IFis directly proportional to the flux, 𝜙. Where p implies number of poles, N is motor speed 

in RPM, 𝜙 is useful flux per pole entering or leaving the armature in weber, k is machine constant, Z is total 

number of armature conductors, c is number of parallel paths through winding between positive and negative 

brushes and 𝜔𝑚 is the motor speed in rad/sec. 

Multiplying equation (16) by armature current (Ia) gives the total electrical power delivered to the armature 

PE, loss due to armature resistance PL in the circuit and Mechanical power developed by the armature PM as 

depicted in equation (18) 

𝑉𝑎𝐼𝑎(𝑃𝐸) = 𝐸𝐼𝑎(𝑃𝑀) + 𝐼𝑎
2𝑅𝑎(𝑃𝐿)                                                                                                                                  18 

From Equation (18), the torque developed by the armature Td is given by 

                     𝑇𝑑 = 𝐾𝐼𝑎                                                                                                                                                         19 

where,    𝐸𝐼𝑎 = 𝑘𝜙𝜔𝑚𝐼𝑎 = 𝑇𝑑𝜔𝑚                                                                                                          

Each thyristor blocking voltage is depicted in Figure 1(d), this plot aids in selection of the thyristor current 

and voltage values. 

 

 

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2.3  Armature and Field Voltages, Currents, firing angles, Speeds and Torque relationships 

Armature control of a separately excited dc motor involves adjusting the supply voltage to the armature 

winding of the motor to control its speed and torque. To regulate motor’s speed and torque, field control 

involves adjusting the field winding’s current. By varying the field current, the motor’s flux can be controlled, 

which will affect speed, torque and efficiency performance. Under steady-state conditions, armature voltage is 

related with firing angle as derived Equation (2). From Equation (16), the motor speed yields  

𝜔𝑚 =
1

𝐾
(

𝑉𝑚

𝜋
(𝑐𝑜𝑠𝛼 + 1) − 𝐼𝑎𝑅𝑎)   =

𝑉𝑚

𝜋𝐾
(𝑐𝑜𝑠𝛼 + 1) −

𝑇𝑑

𝐾2
𝑅𝑎                                                                             20 

Equation (20) depicts speed relationship with developed torque. Developed motor torque can be deduced 

from eqn. (20) as: 

𝑇𝑑 =
𝐾2

𝑅𝑎
(

𝑉𝑚

𝜋
(𝑐𝑜𝑠𝛼 + 1) − 𝜔𝑚)                                                                                                                                   21 

And developed motor power is depicted in equation (22) as 

𝑃𝑑 = 𝑇𝑑𝜔𝑚                                                                                                                                                                          22 

From Figure (1), since both armature voltage and field winding voltage are supplied by the same power circuit 

topology, therefore, the field circuit VF can be obtained as 

𝑉𝐹 =
𝑉𝑚

𝜋
(cos (𝛼𝐹) + 1)                                                                                                                                                   23 

The field current IF is given as 

𝐼𝐹 =
𝑉𝐹

𝑅𝑓
=

𝑉𝑚

𝜋𝑅𝑓

(𝑐𝑜𝑠𝛼𝐹 + 1)                                                                                                                                           24 

Based on Equations (16) and (17), the relationship between the armature and field currents is given as: 

𝐼𝑎 =
1

𝑅𝑎
(

𝑉𝑚

𝜋
(𝑐𝑜𝑠𝛼 + 1) − 𝑘𝐼𝐹𝜔𝑚)                                                                                                                              25 

From Equations (19), (24) and (25), the motor torque developed can be expressed as 

𝑇𝐹 = 𝑘𝐼𝐹𝐼𝑎 =
𝑘𝑉𝑚

𝜋𝑅𝑓𝑅𝑎
((𝑐𝑜𝑠𝛼𝐹 + 1) (

𝑉𝑚

𝜋
(𝑐𝑜𝑠𝛼 + 1) − 𝑘𝐼𝐹𝜔𝑚))                                                                        26 

𝑃𝐹 = 𝑇𝐹𝜔𝑚                                                                                                                                                                          27 

3. Results and Discussion 

3.1  Semi-converter 

The output voltages and currents of a semi-converter depend on several factors including the topology of the 

converter circuit, the type of power switch devices used, the control strategy employed, and the load 

connected to the converter.  The output voltage 𝑣𝑜(𝜔𝑡) of Equation 3 is typically a pulsating DC waveform 

as depicted in Figure 2. The resulting voltage waveform varies between 0 V and 325 V. The average output 

voltage of a rectifier circuit can be calculated using Equation 2 and also called the armature voltage, Va. The 

output current 𝑖𝑜(𝜔𝑡) of Equation 10 is typically also a pulsating DC waveform as depicted in Figure 3 and the 

resulting current waveform varies between 4 A to 28 A. Equation 9 shows the formular for the average output 

current otherwise called armature current, Ia. The harmonics in the output voltage waveform versus firing 

angle is depicted in Figure 4. The highest normalized harmonic amplitude occurred at n equal to 2 with 60 

degrees firing angle.  

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Figure 3: Outputs voltages and currents waveforms 

 

 

Figure 4: Harmonic index against firing angle plot 

3.2  Separately excited dc motor 

The relationship between armature and field voltages and currents against developed torque in a separately 

excited DC motor is depicted in Figure 5. However, generally, increasing the armature voltage increases the 

torque output of the motor, up to a point of diminishing returns and saturation effects. The speed is directly 

influenced by the armature voltage and current as depicted in Figure 6. Also, the speed is inversely influenced 

by the field voltage and current. Armature and field voltages and currents are plotted against the firing angles 

as shown in Figure 7. It is observed that the increase in firing angle indirectly affects the armature and field 

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voltages and currents. The relationship between the machine speed, current and torque is depicted in Figure 

8. The armature and field powers and torques in a separately excited DC motor are influenced by the armature 

voltage, armature current, field voltage, field current, and mechanical load as depicted in Figure 9. The machine 

speed is determined by the balance between the mechanical output torque, load torque, and the motor's 

characteristics. Adjusting the armature voltage and field current can control the motor's speed and torque 

characteristics, allowing for precise speed regulation and torque control in various applications. The three-

dimensional waveform of torque, power and machine speed is as plotted in Figure 10. 

 

Figure 5: Armature and field voltages and currents against torque 

 

Figure 6: Armature and field voltages and currents against machine speed 

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Figure 7: Armature and field voltages and currents against firing angles 

 

Figure 8: Armature and field currents and torques against machine speed 

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Figure 9: Armature and field powers and torques against machine speed 

 

Figure 10: Three-dimensional waveform of torque, power and machine speed 

 

 

 

 

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Table 1: Parameters for separately excited dc motor drive 

Parameter Value 

Vs 230√2sin𝜔𝑡 V 

Motor EMF, E 200 V 

Ra 6.5 Ω 

La 25mH 

Ia 15 A 

𝛼 =  𝛼𝑓 15𝑜 

F 50 Hz 

N 1500 RPM 

Rf 120  

4. Conclusion 

The implementation of thyristor-based control for a separately excited DC motor driven by a single-phase 

semi-converter demonstrates significant advancements in the precise control of motor speed and torque. The 

system leverages the ability of thyristors to modulate voltage and current supplied to the motor, enabling 

effective control over its operational parameters. 

This approach offers several advantages, including improved efficiency, reduced energy consumption, and 

enhanced system reliability. By providing smooth and adjustable control, the method ensures optimal 

performance across a wide range of load conditions, making it particularly suitable for industrial and 

automation applications. Moreover, the use of a single-phase semi-converter simplifies the design and reduces 

the overall cost, without compromising the system's control accuracy. This implementation highlights the 

potential for further integration of power electronics and motor control technologies to achieve more 

compact, efficient, and versatile systems. 

Future work could explore extending this control strategy to multi-phase converters, incorporating advanced 

control algorithms, and addressing harmonics to further improve performance and reduce electrical noise. 

References 

Ahmed, MMR., Elemary, AA., Alaas, ZM. and Hamada, AM. 2023. Torque Control of a 5 kW, 220 V Separately 

excited DC Motor using Microcomputer, International Journal of Power Electronics and Drive Systems 

(IJPEDS), 14(2): 727 – 740. 

Asadi, F. and Eguchi, K. 2019. Comparison of Different DC Motor Modeling Techniques, Journal of Electronic 

Research and Application, 2(2): 1 – 4. 

Dubey, GK. 2009. Fundamentals of Electrical Drives, Narosa Publishing House, New Delhi Chennai Mumbai 

Kolkata, 60 - 139. 

Dubey, T. and Sharma, JK. 2022. Efficient Speed Control of Thyristor fed DC Motor Drive using Interval Type-

2 Fuzzy Logic Controller, Advances and Application in Mathematical Sciences, 21(11): 6571-6588. 

El-Kholy, EE., Shokralla, SS., Morsi, AH. and El-Absawy, SA. 2004. Improved Performance of rolling-mill drives 

using fuzzy hybrid-PI controller, Electromotion, 11: 213 – 224. 

Hameed, HQ. and Ali, FM. 2016. Design of a PC-based DC motor speed controller, Diyala Journal of 

Engineering Sciences, 9(2): 1–11. 

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Arid Zone Journal of Engineering, Technology and Environment, March 2025; Vol.21(1):145-156. ISSN 1596-2490; e-ISSN2545-5818; www.azojete.com.ng 

Corresponding author’s email address: geraldiyoke@mouau.edu.ng  156 

Hareb, M., Ekhail, M. and Hareb, F. 2021. Separately Excited DC Motor Speed Control, Simulation Case Study, 

1st International Mahreb Meeting of the Conference on Sciences and Techniques of Automatic Control and 

Control Engineering MI-STA, 47 – 51. 

Hassan, AY., Rohieem, AG. and Salem, SMS. 2014. Direct torque control of non-salient pole AFPMSMs with 

SVPWM inverter, International Journal of Power Electronics and Drive Systems, 13(4): 2014–2023.  

Hughes, A. 2006. Electric motors and drives: Fundamentals, Types and Applications, Elsevier Ltd, Linacre 

House, Jordan Hill, Oxford OX2 8DP, 134 – 164. 

Kandpal, M., Rai, JN. and Aggarwal, A. 2015. Comparative study of Speed control of Separately Excited DC 

Motor using PI controller and Fuzzy Logic Controller, International Journal of Electronics, Electrical and 

Computational System, 4: 27 – 36. 

Krishnan, R. 2001. Electric Motor Drive: Modeling, Analysis, and Control, Prentice Hall, Inc. Upper Saddle 

River, New Jersey, 114 – 117. 

Namdeo, R., Sharma, CS. and Minz, RB. 2014.  Analysis of Speed for Separately Excited dc Motor using all 

Types of Single-phase and Three-Phase Rectifiers, International Journal of Engineering Research & Technology 

(IJERT), 3(9): 305 – 312. 

Nguyen, KK. and Nguyen, TT. 2019. The sensorless control system for controlling the speed of direct current 

motor, Indonesian Journal of Electrical Engineering and Computer Science, 16(3): 1171-1178. 

Onah, AJ., Awah, CC. and Diyoke, GC. 2022. Speed Control of Direct Current Motors, Nigerian Research 

Journal of Engineering and Environmental Sciences, 7(1): 319 – 329. 

Perelmuter, V. 2012. Electrotechnical Systems: Simulation with Simulink® and SimPowerSystems TM, CRC 

Press. 

Poornima, P., Suganya, P., Kumaresan, N. and Subbiah, M. 2006. Operating modes of Single –phase Thyristor 

converter fed dc drives using Phase angle control scheme-A Monograph, IEEE International Conference on 

Industrial Technology, Mumbai, 2402 – 2407. 

Rashag, HF. 2019. Improved speed response of DC motor via intelligent techniques, International Journal of 

Advances in Applied Sciences (IJAAS), 8(3): 204-207. 

Saini, P., Rawat, N. and Dixit, A. 2020, Design and Analysis of Thyristor based DC Drive System for Speed 

Control of DC Motor, International Journal of Advanced Research in Engineering and Technology (IJARET), 

11(5): 921-928. 

Sami, SS., Obaid, ZA., Muhssin, MT. and Hussain, AN. 2021. Detailed modelling and simulation of different DC 

motor types for research and educational purposes, International Journal of Power Electronics and Drive 

Systems (IJPEDS), 12(2): 703-714. 

Sharma, CS., Singh, K. and Tamrakar, R. 2016. A Thyristor Based Speed Control Techniques of Separately 

Excited dc Motor, International Journal of Scientific Development and Research (IJSDR), 1(11): 13 – 25. 

Tiwari, S., Unni, AC., Rajanivedha R., Singh, GJ. and Ongsakul, W. 2019. Harmonic Analysis of Separately 

Excited DC Motor Drive, Innovations in Power and Advanced Computing Technologies (i-PACT), 1-7. 

Virendra SS., Virendra, J. and Anil, KC. 2013. Different Speed Control Techniques of DC Motor: A 

Comparative Analysis, IJLTEMAS 2(7): 112 – 118. 

 

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