Scientific paper ID 2144 : 2021/3

The static nature of the powerful semi-conductor convertors is attributable

to the fact that the electric energy is converted in a semi-conductor structure without

mechanical movement and, subsequently, without the wear-and-tear of parts due to friction.

Here we can only observe the motion of electric charges and their carriers following the laws

of electrodynamics. These convertors operate in a contactless manner as the electric current

is switched on and off without a visible break of the circuit, without an electrical arc and

without the wear-and-tear of the material at the switching point.

The high energy efficiency of semi-conductor convertors is determined by the voltampere

features of the power semi-conductor devices, which are close to the ideal features of

switching devices without loss. They have high electric conductivity (low voltage reduction) in

the forward direction of the passage of electric current and high electrical resistance (low

return current) in the opposite direction on a closed circuit. Therefore, electric energy is

converted at a minimal loss.

The circuits of power semi-conductor convertors have developed rapidly over the past

twenty years and are almost identical at present. Recently, certain advancement was attained

in the circuit solutions of power and control circuits with the use of microprocessors and

optoelectrical elements. Also, the МОSFET and IGBT technologies had replaced thyristors.