A three phase inverter uses sinetriangle PWM generation The

A three phase inverter uses sine-triangle PWM generation. The switching frequency is 1950 Hz, and the fundamental waveform being generating is a 230 Vrms phase-neutral waveform at 50 Hz. What is the frequency modulation ratio m_p? If the modulation amplitude ma = 0.83, what is the DC bus voltage? Calculate the amplitude and frequency of the first six most significant switching harmonics. The three phase inverter from Q1 is now implemented based on space vector modulation (SVM) techniques. The switching frequency is 1950 Hz as before. In one switching cycle, the sequence of the vectors is based on the following switching order: The individual timing of the three space vectors is calculated to achieve an output voltage of 230 Vrms phase-neutral as before from the DC bus voltage calculated in question 1. Calculate the voltage vector magnitude Vref and angle a for the third switching interval after the a-phase zero crossing (defined as alpha = 0 degree). Calculate the total duration of one switching cycle. Calculate the switching vector durations t_1, t_2, and to for the third switching interval after the a-phase zero crossing. Using Matlab, LTspice, or software of your choice, accurately plot the inverter output voltages Va, Vb and Vc for this switching cycle. Using Matlab, LTspice, or software of your choice, accurately plot the motor star point voltage Van, motor phase neutral voltage Van, and phase-phase voltage Vab. Using your code, plot the motor phase-phase voltage waveforms Vab, Vbc, Vca for the entire 20 ms fundamental period.

Solution

As per chegg guidelines ,it has more than 1 questions

so we will attempt first question

1 a) frequency modulation ratio = 50/1950= 0.026 = mf

b) mo =0.83 = Vrms/Vdc

Vdc = 315 V

c) Vo(fundamental) = 3Vs*Sin(nwt)/n*pi,

we can calculate for first 6 harmonics , n= 1 to 6

Vs = 230*1.414= 315V

frequency = nfs

n= 1 to 6\'

fs = 50Hz