Measuring the real parameters of single-phase voltage source inverters for UPS systems

Drawbacks of impedance networks

“…Notably, R LZ is the real resistance of the inductor in the impedance network and is much higher than the serial resistance R LZDC for the DC current because of the power losses in the inductor core . The coil cores in the laboratory model are made of Super‐MSS alloy powder .…”

“…However, none of these papers use the state space averaging method to create an equivalent model of the output impedance. The output impedances of the impedance networks implement 2 additional resonant frequencies to the control transient function that are very close to each other and to the fundamental frequency; thus, the damping resistances in the output impedance model determine the final change in the transient function …”

“…The coil equivalent resistance depends on the type of the core magnetic material used and its properties because this resistance depends on the power losses in the core. The serial resistance greatly increases with the magnetizing current amplitude and frequency (the power losses caused by the switching operation with f c dominate the other power losses) . The values of the coil inductances change with the frequency and amplitude of the magnetizing current.…”

“…The standard laboratory inductance‐capacitance‐resistance bridge (eg, Hameg HM 8118) measures the serial resistances for sinusoidal voltages and currents. The method of measuring the serial resistance of the output filter coil, averaged in the fundamental period of the operating point, was presented in literature . For alloy powder materials (eg, Super‐MSS), the serial resistances are assigned as R LZ = 1.5 Ω (Super‐MSS alloy powder) and R LFe = 5 Ω (Material Mix.…”

“…For alloy powder materials (eg, Super‐MSS), the serial resistances are assigned as R LZ = 1.5 Ω (Super‐MSS alloy powder) and R LFe = 5 Ω (Material Mix. ‐26, iron powder), according to the measurements in Rymarski …”