JSS Academy of Technical Education

JSS Campus, Vishnuvardhan road, Bengaluru-560060

DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING

Internship presentation on:

“LOAD COMMUTATED INVERTER FED SYNCHRONOUS MOTOR”
Carried out at:
BHEL-EDN

Presented by:
Internal guide NAMRATHA GK External guide
Dr P M Shivakumarswamy 1JS21EC086 Mr. Shailesh Kumar
Professor SR Manager
Dept. of ECE, JSSATEB COE Dept, BHEL-EDN
 BHEL-EDN
(10 WEEKS)

• Bharat Heavy Electricals Limited (BHEL) is an Indian central public sector undertaking which is under the
ownership of Ministry of Heavy Industries, Government of India.
• It is based in New Delhi, India. Established in 1956, BHEL is India’s largest government-owned power
generation equipment manufacturer.
• It was established in 1956 ushering in the heavy electrical equipment industry in India. In 1991, BHEL was
converted into a public company.
• Over time, it developed the capability to produce a variety of electrical, electronic, and mechanical equipment
for various sectors, including transmission, transportation, oil and gas, and other allied industries.
• Right from developing country’s power generation capacity to creating multiple capabilities in country’s core
industrial & strategic sectors, BHEL is deeply aligned to the vision of a self-reliant India.
• BHEL serves their customers with a comprehensive portfolio of products, systems and services in the
areas of power-thermal, hydro, gas, nuclear & solar PV; transmission; transportation; defence &
aerospace; oil & gas and new areas like BESS and EV chargers.
INTERNSHIP GOALS
• Practical Industry Exposure: Gain hands-on experience in power generation, manufacturing, and
engineering processes.
• Skill Development: Enhance technical, problem-solving, and analytical skills through industrial
training and project work.
• Application of Theoretical Knowledge: Bridge the gap between academic learning and real-
world applications by working on live projects.
• Professional Growth: Improve communication, teamwork, and time management skills by
collaborating with professionals in the field.
• Understanding the functioning of high-power motors and inverter systems.
• Study synchronous motor operations.
• Analyze load commutation techniques.
TECHNICAL LEARNING
• During the internship at BHEL, I learnt many new concepts along with some basic
concepts of MATLAB and SIMULINK.
• I was introduced to many new tools such as KiCad and draw.io which I used to
sketch my project model.
• Basic knowledge and understanding of analog and digital electronics.
• Detailed learning about microcontrollers and HMI integration.
• I was given introduction about railway propulsion system, high power converters
and inverters used to deliver power to moving wheels.
• I also visited many other departments like system testing, PCB, sub-assembly and
traction converters.
PROJECT ANALYSIS
PROBLEM STATEMENT:
AC induction motors lack precise speed control, making them unsuitable for critical applications.
Induction motors draw reactive power, leading to poor power factor, especially at light loads. These
induction motors will not be having self commutation mechanisms which might increase the need for
external circuits for commutation process. This will decrease system efficiency, increases switching
losses and are more expensive.
OBJECTIVE:
To design and implement load commutated inverter fed synchronous motors for precise speed and
torque control by minimizing harmonics and introducing self commutation features using thyristor
angle firing mechanisms. This helps in precise control over speed, torque & controlled output
voltage, increases efficiency of the system while making it suitable to drive high power industrial
applications by drawing less power.
BLOCK DIAGRAM
IMPLEMENTATION
• The three-phase AC voltage from the power supply is fed into a thyristor-based rectifier. Unlike a diode-based rectifier, the
thyristor rectifier can be controlled to adjust the output voltage.
• This controlled rectification allows for phase control, enabling the system to regulate the amount of DC voltage generated
from the AC input. The output from the thyristor rectifier is a pulsating direct current (DC). This pulsating DC is directed
to a DC link, which typically includes a smoothing capacitor and a reactor (inductor).
• By controlling the firing angles of the thyristors in the inverter, the output voltage and frequency can be modulated,
allowing for precise control of the motor's speed and torque. Also due to self commutation process the system does not
require external switching circuit which is the main advantage of this project.
• In addition to speed control, the actual current flowing to the motor is monitored. This measurement ensures that the motor
operates within safe current limits
• The measured current is compared to a desired current reference derived from the torque requirement.
• The current error is processed through another PI controller, which adjusts the inverter’s operation to maintain the required
current level.
• The feedback from both control loops enables the system to make dynamic adjustments. If the load increases and causes a
drop in speed, the control system increases the inverter output to restore the desired speed.
• The use of thyristor-based rectification and inversion allows for high efficiency, reliability, and responsiveness, making the
system suitable for various industrial applications.
THYRISTOR CIRCUIT
WORKING OF THYRISTOR
• In self-commutation, the thyristor turns off automatically by utilizing circuit
conditions (back emf of motor) rather than an external commutation circuit. This
process typically involves an LC resonant circuit or a charged capacitor that
generates a reverse voltage across the thyristor, forcing it to turn off once the
forward current drops below the holding current.
• Initially, when the thyristor is triggered by a gate pulse, it conducts and allows
current flow. During the conduction period, an appropriately designed circuit
element (such as an inductor or capacitor) stores energy.
• When the thyristor needs to turn off, this stored energy is released in a manner that
applies a reverse voltage across the device, reducing the anode current to zero. As
a result, the thyristor enters the blocking state, successfully achieving self-
commutation without the need for forced external switching components.
HMI INTEGRATION
• HMI, or Human-Machine Interface, is a system that facilitates interaction between humans and machines,
allowing users to control and monitor automated systems through visual displays, touchscreens, buttons, or
other inputs. Found across a range of industries such as manufacturing, healthcare, and automotive, HMI
systems are vital for enabling efficient, user-friendly operation and control over complex processes and
machinery.
• This page is typically referred to as the HMI Main Screen or Home Screen. In an HMI system, the main
screen serves as the primary dashboard or interface where operators can view the status of the equipment,
access critical controls (such as alarms and trend analysis), and monitor real-time information (like date and
time).
• This screen acts as a central hub, allowing users to navigate to other pages, view alarms, or check equipment
trends. This page also contains Control Buttons on the left, for navigation or operational controls.
RESULTS

• The graph shows periodic fluctuations, indicating a controlled variation in load voltage and current. This suggests
efficient operation of the system with minimal distortions.
• The voltage waveform (yellow) is higher in amplitude than the current waveform (blue), which is expected in a resistive
or inductive load scenario. The phase relationship might indicate the type of load used.
• The presence of periodic but controlled variations suggests that the system is effectively regulating power delivery to
the load, which is crucial in applications like power converters or inverters.
• The third and fourth waveforms represent Gate Pulses for power electronic switches (likely IGBTs, MOSFETs, or
thyristors).
• By varying the timing and duration of the gate pulses, the inverter controls the frequency of the phase voltages
applied to the motor. The frequency of these voltages determines the motor's speed, while the amplitude impacts
torque.
• Torque Control: The amplitude of the inverter's output voltage can be adjusted through the gate pulses, directly
affecting the motor's torque.
• Commutation: Gate pulses control the commutation between motor phases, keeping the rotor’s magnetic field
synchronized with the stator field in synchronous motors. Hence it is self commutated and reduce need of external
switching circuits.
UNIFIED MENTORS PVT LTD.
(8 WEEKS)

• Unified Mentors is a professional training and career development

company that specializes in providing industry-relevant skills,
mentorship programs, and internship opportunities.
• Unified Mentors emphasizes practical exposure, virtual sessions, and
face-to-face training to equip interns with industry-relevant skills.
• Interns explore topics such as supervised and unsupervised learning,
deep learning, neural networks, and natural language processing
(NLP).
• They also work with essential tools like Python, TensorFlow, Scikit-
learn, and Pandas.
KEY LEARNINGS
• Introduction to machine learning, supervised, non supervised learning.
• Regression algorithms to predict numerical values.
• Linear regression, classifications , advantages and disadvantages.
• Least square techniques such as Mean Squared Error (MSE) or R-
squared (R²) to improve accuracy.
• Basics of XG Boost features, random forest and other decision making
algorithms.
CONCLUSION
• The internship provided hands-on experience in an industrial environment at
BHEL, allowing practical application of theoretical knowledge, while Unified
Mentors offered structured mentorship and training.
• Gained technical knowledge in core electronic fields and implemented the same in
projects to make real time changes in efficient working of synchronous motors.
• Improved problem-solving, teamwork, and communication skills, essential for
career growth in both industrial and corporate settings.
• Worked on real-world projects at BHEL, gaining exposure to large-scale industrial
operations.
• Gained basic knowledge on machine learning algorithms which served as
foundation for advanced concepts.
THANK YOU