NAME: MURITHI JOHN MWANGI
REG NO: EG209/104377/20
UNIT: ELECTRICAL MACHINE DRIVES
UNIT CODE: EET 3454
TITLE: LABORATORY REPORT
LAB 1: THREE PHASE INDUCTION MOTOR SPEED CONTROL MODULE
Exercise 5.4
5.4 Ratio between the Output Voltage of the SPEED REGULATOR Block and the Output
Frequency of V/F1 FCT
Objectives
Determine the relationship between the output voltage from the SPEED REGULATOR block and
the output frequency of the V/F1 FCT module.
Introduction
The speed regulator block plays a crucial role in managing the speed of a three-phase induction
motor. By adjusting the output voltage, this component ensures that the motor maintains the
desired speed. Understanding the relationship between output voltage and resulting frequency is
essential for effective motor regulation.
Apparatus
1. Three Phase Induction Motor Speed Control Module (Model: G37)
2. Oscilloscope
Procedure
i. Confirmed that module G37 is switched off and devoid of any power supply voltage.
ii. short circuit was created between terminals 3 and 4.
iii. connection between terminal 29 and 30 was established using a cable.
iv. Positioned switch I1 to the STOP setting, set I2 to 50Hz, and adjusted the ACC and DEC
potentiometers to their minimum values. Provided the module with the necessary voltages.
v. Activated the module by turning switch I1 to the START position.
vi. Fine-tuned potentiometer P1 to attain a voltage of 0.5 V at terminal 38.
vii. Utilized an oscilloscope to measure the frequency of terminal 17 (output of voltage-to-
frequency converter VF1).
viii. Employed an oscilloscope to measure the frequency of terminal 11, which serves as the
signal driving the MOSFET.
ix. Recorded all measurements in the designated table within the results section.
x. Repeated the aforementioned measurements, varying the voltage values at terminal 38 by
adjusting potentiometer P1.
xi. Graphed the recorded values to evaluate the linearity of the output signals.
Results
Results
The table below shows the recorded measurements:
VOLTAGE FREQUENCY FREQUENCY
TERMINAL 38 TERMINAL 17 TERMINAL 11
0.5 v 9.78521 4.6459
1v 21.63 7.335
1.5v 47.11 16.81
2v 74.6677 25.6677
2.5v 97.7465 28.0167
3v 117.138 19.6341
3.5v 136.020 17.1914
4v 143.680 16.8340
Discussion
The experiment’s results revealed a connection between the output voltage of the speed regulator
block and the frequencies observed at terminals 17 and 11. Evaluating the linearity of these output
signals provides valuable insights into the motor speed control performance facilitated by the
module.
Conclusions
Through this experiment, we effectively explored the correlation between the output voltage of
the SPEED REGULATOR block and the output frequency of the V/F1 FCT. The gathered data
contributed to comprehending the module's behavior and enhancing motor speed control in real-
world scenarios.
LAB 2: D.C SHUNT MOTOR DRIVE
Objectives
To assess the performance characteristics of a DC shunt motor connected to a propulsion system.
Introduction
Direct current (DC) motors are widely utilized in various industrial and commercial settings due
to their simple operation, reliability, and ease of regulation. Among DC motors, the DC shunt
motor stands out for its ability to maintain stable speed control across a wide range of loads.
Apparatus
1. Multimeter
2. Drive System
3. DC Motor
Procedure
1. TP1 and TP2 were interconnected, effectively joining potentiometer P1 to the set-point
input of the drive. This potentiometer enabled the adjustment of the control voltage
within the range of -10 V to +10 V, corresponding to motor speed variations between -3000
rpm and +3000 rpm.
2. The main switch, located at the back of the drive, was activated.
3. The SA2 ENABLE switch was toggled to the "ON" position, indicated by the illumination
of the green LED EN.
4. Potentiometer P1 was manipulated to alter the motor's rpm in both clockwise and
counterclockwise directions.
Results
i. Clockwise Directions.
Speed(rpm) Applied Voltage Armature Current(mA)
600 2 1.84
1200 4 3.43
1800 6 4.91
2400 8 6.76
3000 10 8.56
ii. Anticlockwise Directions
Speed (rpm) Armature Current(mA) Field Current(mA)
600 -1.89 11.96
1200 -3.20 11.94
1800 -4.97 11.92
2400 -6.50 11.89
3000 -8.74 11.85
Discussions
Reducing the resistance in the speed control circuit by adjusting the potentiometer led to an
increase in the voltage across the armature, causing the motor's speed to rise. This speed
increase correlated with an elevation in the back electromotive force (EMF) produced by the
motor. With the armature resistance remaining unchanged, the gap between the applied voltage
and the back EMF decreased. As a result, the armature current surged to supply the additional
mechanical power required for the heightened speed.
Conclusions
The experiment demonstrated that when the applied voltage increased in the clockwise
direction, the motor's speed increased accordingly, leading to a rise in armature current due to
the increased demand for mechanical power. Conversely, in the anticlockwise direction, an
increase in speed resulted in a corresponding elevation in back electromotive force (EMF),
which countered the applied voltage and caused a decrease in armature current. Throughout
these variations, the field current remained relatively constant, as the motor operated under
unloaded conditions.
1. Lab 3: THE SIGNALS CURVES BEFORE THE PWM GENERATION
Objective
1. To trace the curves that generate the PWM signal.
Introduction
In motor control systems, Pulse Width Modulation (PWM) is a crucial method for achieving
precise control of speed and torque in electric motors. However, before the PWM signal can
be generated and applied for motor control, it undergoes several transformations from its initial
waveform. This activity aims to investigate and assess these preliminary signals, which serve
as the foundation for PWM synthesis, thereby enhancing comprehension of their significance
in the process.
Apparatus
Two channels oscilloscope.
Procedure
1. Connected the CH1 probe to terminals 13 & 20.
2. Verified the presence of a triangular signal Vpp = 20V, F = 10KHz.
3. Connected CH2 probes to terminals 17 & 20.
Results
The final wave as presented by the oscilloscope was as shown above which was the addition
of the two input waves.
Discussion
Pulse-width modulation, commonly known as PWM, is a modulation method that changes the
pulse signal’s width [1] in electrical systems to regulate the average power supplied to a load.
PWM is particularly helpful for effectively regulating the output of audio amplifiers, the speed
of motors, and the brightness of light. PWM is an elegant way of referring to a particular kind
of digital signal.
conclusion
Understanding the characteristics of signal curves before PWM generation is essential for
designing efficient and reliable electronic systems. By analyzing input signal properties,
addressing noise and distortion challenges, and evaluating transient responses, engineers can
develop PWM systems tailored to meet the requirements of diverse system applications.
References
[1] g. f. geeks. [Online]. Available: https://www.geeksforgeeks.org/pulse-width-modulation-
pwm/. [Accessed 7 04 2024].
