Abstract:

In this paper the experience by the on-line teaching of non-sinusoidal modes of electrical circuits, which applied during the Covid-19 pandemic, is presented.

The Covid 19 pandemic changed the world. Student education has also changed. Universities passed to education in the electronic environment for long time. On the other hand, the quality of students' education had to be maintained and they had to acquire practical abilities. The lecturers and students used different virtual environments to study electrical devices and the processes that take place in their work.

Sinusoidal alternating modes are often the preferred operating modes of electrical devices. But in practice, real modes only come close to ideal sinusoidal functions. In other classes of devices, such as those used in communication technology, normal electromagnetic processes generally develop at pronounced non-sinusoidal currents and voltages.

The reasons that lead to the presence of non-sinusoidal currents and voltages in electrical circuits are: energy sources provide non-sinusoidal voltage or current due to imperfections in the structure or due to their special purpose; The circuit includes nonlinear elements or elements with time-varying parameters that deform the sinusoidal currents and voltages. A combined effect of the above two reasons is also possible.

This paper presents a new approach in the study of periodic non-sinusoidal modes in the course of Electrical Engineering. A program has been developed in Matlab to decompose some of the common non-sinusoidal periodic functions in the Fourier order. A set of commands is proposed through which students can compile a program for calculating voltages and currents in electrical circuits for different harmonics. The source code for the calculation of currents and voltages in a specific electrical circuit is given. Virtual experimentation of the considered electrical circuit was performed.

The method, which is proposed in this paper, was tested in the online training during the quarantine because of Covid-19 pandemic in the disciplines, studied by students majoring in "Electrical Engineering" or "Computer and communication systems" at the Faculty of Physics and Technology at the University of Plovdiv “Paisii Hilendarski” (Bulgaria). Observations are that the use of virtual environment helps students to understand easily non-sinusoidal modes in electrical circuits and calculate the non-sinusoidal currents and voltages of different schemes.

Keywords:

Non-sinusoidal currents and voltages, Education, Electrical Engineering.