The document describes the design and construction of a closed-loop speed control system for a brushless DC motor by seven students supervised by a faculty member. It aims to replace conventional DC motors with more efficient brushless DC motors that allow variable speed operation through closed-loop control. The system involves designing an electronic control circuit, constructing the motor casing and assembling the working model, and testing the system performance. It is expected that the motor speed will be proportional to the applied control variable and maintain different speed settings.

1. DESIGN AND CONSTRUCTION OF A CLOSED-LOOP
CONTROL OF BRUSHLESS D.C MOTOR
BY
FRIDAY CLIFFORD
CET/ND/EEE/2019/012
COREM CHARLES
CET/ND/EEE/2019/026
BRISKA BEJAMIN
CET/ND/EEE/2019/048
JOSHUA BOYILADI
CET/ND/EEE/2019/061
BABANAI DIKKO
CET/ND/EEE/2019/110
BULUS DAWI
CET/ND/EEE/2019/116
BENJAMIN DOGARA
CET/ND/EEE/2019/129
SUPERVISED BY
MR XX XXXX XXXX
OCTOBER, 2021.

2. INTRODUCTION
Permanent-magnet excited brushless DC motors are becoming increasingly attractive in a large
number of applications due to performance advantages such as reduced size and cost, reduced
torque ripples, increased torque-current ratio, low noises, high efficiency, reduced maintenance
and good[1-4]
Household appliances are one of the fastest growing markets for BLDCs [1]. Common
household appliances which use electric motors include air conditioners, refrigerators, vacuum
cleaners, washers and dryers. These appliances have relied on traditional electric motors such
as single-phase AC motors including capacitor- start, capacitor- run motors, and universal
motors. However, consumers now demand better performance, reduced acoustic noise and
higher efficient motor for their appliances. Hence, BLDC have been introduced in order to fulfill
these requirements[1]
Most popular brushless DC motors are mainly three phases [5-7] which are controlled and
driven by full bridge transistor circuits. Together with applying permanent magnet excitation, it
is necessary to obtain additional torque components. These components can be obtained due
to a difference in magnetic permeance in both quadrature and direct axis; therefore,
reluctance torque is developed and torque null regions are reduced significantly [8, 11].

3. STATEMENT OF PROBLEM
Conventional DC motors are being
replaced by BLDCs due to their high
efficiency and low noise features which
are more desirable for consumers.
However there is a a major
disadvantage associated with BLDCs
regarding the variable speed operation.
This problem defined gives rise to
various studies done in order to
operate the BLDCs with constant speed
especially by closed loop control as in
this study.

4. AIM AND OBJECTIVES
The Aim of this project is to design and
construct a brushless dc motor with its
closed loop speed control system. The
objectives are as follows
 To design the electronic control circuit
for the project.
 To construct a casing and assemble the
working model.
 To test and evaluate the performance
of the system.

5.  Jianwen (2013) worked on Direct Back EMF Detection Method for Sensor less Brushless DC (BLDC) Motor Drives. In
his work a microcontroller was used to determine induced voltages in the windings at intervals after each phase.
The residual voltage was used by the microcontroller to fire the next winding into conduction. In this way the speed
of the motor was made dependent on the induced emf thereby needing no sensors.
 Rambabu (2017) modeled and controlled a brushless dc motor. In his work the brushless dc motor was modeled
mathematically. In his work In this scheme, equivalent output of three hall sensors determine the rotor position at
any instant of time and accordingly switch the six step inverter to drive the motor. The model is based on phase
voltage and electromagnetic torque equation. Further analysis has been carried out with transfer function to
achieve desired level of performance. Moreover, the ideal Back EMF is also derived from mechanical speed and
mechanical angle of the rotor. A wide variation of speed control is accomplished with a PI controller due to its
simple control structure and ease of implementation. The final analysis on the speed-torque characteristics for the
designed Brushless DC motor show quite satisfactory output for varying (0-20 N-m) load torque applications.
 Gambhir and Jha (2018) constructed a brushless DC motor. The constructed motor was made of aluminum former
with provision for the motor poles and winding, Hall effect sensor was included in the design to detect the end of
each cycle of turn of the rotor. The control circuit was made of discrete components like AD 433 motor control
interface IC, a 555 timer IC for production of clock pulses. The mechanical portion was finished by covering the
motor with a cylindrical outer protective cover made of aluminum. The motor was tested with a tachometer to
establish the control due to the closed loop arrangement. Test results were favorable.
 Gamazo-Real et al (2012), applied Position and speed control of brushless DC motors using sensor less techniques.
The poles were used as the feedback loop, the phase difference generated by the induced voltages in the poles
were utilized in the speed control of the motor. The project worked efficiently except for overheating due to recoil
effect generated by the conflicting back induced voltages.
In summary all the systems of speed control reviewed above were efficient but the control scheme are very complex
involving high technology and microcontrollers skills except for the work by Gambir 2018 that used conventional discrete
components. The proposed work differ from all by its being very simple in approach, very cheap in construction and less
complex in nature.
LITERATURE REVIEW

6. BLOCK DIAGRAM OF THE SYSTEM

7. MOTOR CONSTRUCTION

8. CONTROL SCHEMATIC

9. EXPECTED RESULTS
1. The constructed device will be able to
detect rotate at varying speeds if the
right power is applied.
2. The constructed device will be able to
maintain different speed settings on
the controller.
3. It is expected that the speed of the
motor will be proportional to the
applied control variable.

10. REFERENCES
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