Abstract:

The authors of the article share their experience in using NI Multisim simulation software in order to assist students trained in engineering specialties in higher education in the study of diode rectifiers and voltage regulators.

Electronic devices need power. Although AC energy is the most available, a small percentage of it is powered directly from the standard AC network. Therefore, students' understanding of the key concepts related to voltage conversion and the available practical alternatives is a good start to master successfully the Power Supplies operation’s principles.

The courses in which Power Supplies are taught are included in the curriculum of almost all technical specialities. Due to the unequal level of preparation of students, a different approach to teaching is needed. For some specialities, it will be useful for learners to gain more knowledge by computer-based learning using computer models and simulations. In specialities where this is the main topic, computer simulations support practical training.

The article presents simulation models of one-and-a-half-cycle Half Wave Rectifier and two-and-a-half-cycle Full Wave Bridge Rectifier. Their operation is simulated at active load and in the presence of Smoothing Capacitor. Computer models allow a virtual oscilloscope to monitor the shapes of the signals in their various modes of operation and measure their basic parameters. The virtual concept for visualization of the results of the measured quantities assists students in their preparation for work in real laboratory conditions.

A parametric analysis is performed to investigate the effect of Smoothing Capacitor on the value of the upright voltage and the ripple superimposed on it. The table presents the theoretically calculated and simulated readings of the studied electrical quantities: average value of the rectified voltage, pulsation frequency, pulsating voltage. An analysis of the obtained results is made.

The computer model of the Voltage Regulator, implemented with IC LM317 LM from National Semiconductors, is useful for understanding how the input voltage, which can be up to 40 V, can be regulated at the output in the range from 1.2V to 37V. The model uses measuring probes at nodal points to monitor the change in electrical quantities in real-time. The theoretically calculated and simulated readings of the modified adjustable output voltage are not only presented but compared as well.

Multisim gives students the chance to monitor and master the normal work process of engineering work: design, simulation, testing and debugging, presentation of the results.

The developed models of diode rectifiers and voltage regulators, as well as the research conducted with them, were useful in organising and implementing of online training during the COVID-19 lockdown in the discipline "Power Supplies". This training was applied to bachelors in the following specialities "Computer and Communication Systems " as well as " Hardware and software systems” at the Faculty of Physics and Technology of Plovdiv University Paisii Hilendarski.
The proposed approach to research and teaching of diode rectifiers and voltage regulators provides new opportunities for gaining more knowledge and improving new methods of teaching and learning, aimed at achieving higher quality learning outcomes in engineering education.

Keywords:

Diode rectifier, voltage regulator, NI Multisim.