Assignment 3: Hand-in Assignment T1 2024 – ELEC4614 v1
J Fletcher
April 2024
You are required to submit a Hand-in Assignment for ELEC4614. The mark from your Hand-in Assignment will
contribute 20% of your final class mark. You are expected to submit the Hand-in Assignment via the Moodle link
before 3pm on Friday week 11. Late submissions will not be accepted. You must include a signed cover sheet
declaring that the work submitted is your own work and this must be the first page of the assignment.
By the end of the laboratory schedule you should have completed three or four laboratories and have results, even if
only partial results, for each of these. Students should have experiments 1-4 results or a subset of these.
Over the page there is a list of questions for each experiment. Select one experiment only and answer the questions
posed over the page (taken from the back of the lab sheet) for that experiment using your experimental data when
appropriate. Include when necessary, a circuit diagram and a brief discussion, with comparison, of the experimental
waveforms or data, and that expected using the theory covered in this course. Use relevant formula where
necessary to demonstrate that the theory matches the experiment. Note that the list of questions only covers
Experiment 1, 2, 3 and 4.
The expectation is that you will submit no more than 3-4 A4 pages in total excluding the cover page. The key purpose
of the assignment is to demonstrate that you can match theory to experimental results, and where they don’t match
you can explain why.
Marks will be awarded for:
Presentation and style (20%)
Comparison of results with theory (50%)
Conclusions (30%)
Areas where students often lose marks:
Figures: no caption, no axis labels, small font sizes.
Poor discussion section
Not using experimental results to demonstrate background theory and developed equations
Including all the results then not referring to them and discussing them
Questions to answer (choose only one experiment and answer all the questions below for that experiment)
Experiment 1: Buck Converter
6.3 Describe how iL, vL, ic, vo, iT, and iD change when the converter is operated in continuous conduction and
discontinuous conduction modes. Note that you should use the saved waveforms to substantiate your
explanation.
6.4 Plot the frequency response data for inductor current IL and output voltage Vo versus frequency of D
found in steps 5.15-5.16. Comment on these results and discuss with reference to theory.
Experiment 2: Boost Converter
6.2 Describe how switching frequency fs and the values of L affect the current ripple in the boost inductor
using the saved inductor current waveforms. Do the experiments match the theory?
6.3 Describe how Vo changes with D when the converter operates with discontinuous conduction using your
experimental results to verify theory.
6.4 Describe how iL, vL, ic, vo, iT, and iD change when the converter is operated in continuous conduction and
discontinuous conduction modes. Note that you should use the saved waveforms to substantiate your
explanation.
Experiment 3: Single-phase DC-AC inverter
5.1 What was the effect of increasing the switching frequency with a fixed dead-time of 10µsec on the
harmonic spectrum of the load current? Elaborate this by plotting the RMS values of various harmonic
currents including the fundamental on a graph paper for a few switching frequencies.
5.2 What was the effect of increasing the dead time at a fixed switching frequency on the harmonic
spectrum of the load current? Elaborate this by plotting the RMS values of various harmonic currents
including the fundamental on a graph paper for a few dead times (in µsec) and fs = 10kHz.
5.4 Plot the variation of the RMS output voltage with depth of modulation m.
Experiment 4: Three-phase inverter
6.1 Using data from section 5.3, compare the measured RMS values of the fundamental and the recorded
harmonics of the line-line and line-neutral voltages of the three-phase quasi-square-wave inverter with
their predicted values from equations 2 and 5.
6.2 Plot the measured RMS values of the fundamental and the harmonics of the line-line and line-neutral
voltages of the three-phase quasi-square-wave inverter.
6.3 Comment on the effects of switching frequency on the quality of the SPWM inverter output current
waveform at low and high switching frequencies.