On the impact of operating modes and power supply conditions on the efficiency of power electronic devices

A wide range of modern low voltage power electronic (PE) devices feature sophisticated controls, which aim to improve device performance and ensure better regulation of grid-side ac currents. The implementation of these controls is expected to result in increased device efficiency, improved controllability, higher operating power factors and reduced harmonic emissions. The interactions of individual PE devices and their controls with the supplying network are analyzed in this paper in terms of the total harmonic distortion and emission of main low-order harmonics, which are then used to assess exchanges of powers at fundamental system frequency and nonfundamental (i.e. harmonic) frequencies between the individual PE device and the grid. Based on this analysis, the paper correlates the obtained results for harmonic performance and efficiencies over the entire range of operating powers of the considered PE devices, calculated in accordance with the standard definitions and using some alternative interpretations.