A 12 pulse AC/DC converter fed from 3-phase 400V, 50Hz supply is as shown in Fig.l. A level dc current of 100A is flowing through the load.
1. Build the simulation circuit using MATLAB/SIMULINK/POWE SYSTEM TOOL BOX and carry out the circuit simulation. Show
(1) the input line current waveforms of la, la1 and la2;
(2) output voltage Vdc Vdc1 and Vdc2.
(3) Measure the input current THD value, input current FFT spectrum, and input power factor.
2. (1) Assuming that the transform-1 has a turn ratio of 1:1 and the output voltage Vdc1 and Vdc2 are equal; calculate the turn ratio of the transformer-2.
(2) Calculate (by hand) the average output voltage, the Fourier series expressions of the currents, ia, ia1 and ia2 comment on the input line current harmonics.
(3) Calculate (by hand) the rms value, the average value of the diode currents, the input VA and input power factor.
