Six step three phase inverter given Vdc, f range, R, L, wye load determine effec
ID: 2073047 • Letter: S
Question
Six step three phase inverter given Vdc, f range, R, L, wye load determine effect on THD of Vphase For the six-step three-phase inverter of the figure below, the dc input is 400 V and an output frequency that varies from 25 to 100 Hz. The load is a Y connection with a series RL connection with R = 10 Ohm and L = 30 mH inductance in each phase. What is the effect on the total harmonic distortion (THD) of the line-to-neutral voltage, V_L-N, as the frequency is varied from 25 to 100 Hz (Select the one best answer from the choices given below.) (a) THD_V, L-N increases approximately by a factor of four (from 27% to 7%) (b) THD_V, L-N increases approximately by a factor of two (from 10% to 5%) (c) THD_V, L-N remains constant (at approximately 27%) (d) THD_V, L-N decreases approximately by a factor of two (from 5% to 10%) (e) THD_V, L-N decreases approximately by a factor of four (from 7% to 27%)Explanation / Answer
Correct option is C. % THD does not depend on the frequency. Whatever may be the load the voltage THD is constant. Whereas the current THD depends on the type of the load.