Assesment of dynamic losses in power switches of autonomous inverters with different modulation algorithms

Abstract

When designing an automated electric drive, it is required to provide the necessary quality indicators of speed control as much as possible with the lowest energy losses in it. Assessment of dynamic losses in power semiconductor switches of autonomous voltage inverters (AVI) is due to the need to select optimal control algorithms for them in order to increase energy efficiency in frequency-controlled asynchronous electric drive systems. To solve the set tasks, the method of mathematical modeling has been used. With the help of the developed program, an assessment of the dynamic losses in a high-speed electric drive during its operation in a steady state has been made. At a typical modulation frequency f = 6,000 Hz, which with scalar control algorithms provides a sufficient degree of approximation of the generated phase voltage envelopes to a sinusoidal form, and the use of pulse-width control (WIR) algorithms, significant dynamic losses are observed in the switches of an autonomous voltage inverter. In the course of using the WID algorithms, an accurate approximation of the sinusoidal shape is not required, which makes it possible to reduce the modulation frequency and, as a consequence, reduce the amount of dynamic losses in the AVI keys. Therefore, a comparative assessment of dynamic losses has been carried out for the scheme of a classic three-phased AVI using the algorithms of unipolar and bipolar pulse-width control. The obtained simulation results have shown that the unipolar WID algorithm is more energy-saving compared to the bipolar WID algorithm when used in high-speed electric drives.