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(c) In bipolar PWM output, the magnitudes of some voltage harmonics are quite large, and sometimes larger than the fundamental. Explain how these harmonics can be minimized or eliminated to achieve a low THD percentage?

QUESTION 2 (a) Design a single-phase bipolar PWM inverter that will produce a 75 V rms 60 Hz output across a series RL combination with R = 15 2 and L = 50 mH. The input de voltage of the inverter is 150 V. Select the switching frequency such that the current THD is less than 10 percent. In your design, you will need to; use Table Ql(a) for estimating the amplitude voltage of the fundamental and first harmonics in the output of the inverter, i.e. V1, Vms, Vms -2 and Vmf+2, and specify any assumptions used to simplify the design process. Table Ql(a): Normalized Fourier Coefficients V/Vpc for Bipolar PWM ma 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 n=1 1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.60 0.71 0.82 0.92 | 1.01 1.08 1.15 1.20 1.24 1.27 n = m +2 0.32 0.27 0.22 0.17 0.13 0.09 0.06 0.03 0.02 0.00 n=ms (b) Draw the frequency spectrum of the output voltage as required in (a). Indicate the values of magnitude voltages and frequencies for the fundamental and first harmonics frequencies in your drawing. QUESTION 2 (a) Design a single-phase bipolar PWM inverter that will produce a 75 V rms 60 Hz output across a series RL combination with R = 15 2 and L = 50 mH. The input de voltage of the inverter is 150 V. Select the switching frequency such that the current THD is less than 10 percent. In your design, you will need to; use Table Ql(a) for estimating the amplitude voltage of the fundamental and first harmonics in the output of the inverter, i.e. V1, Vms, Vms -2 and Vmf+2, and specify any assumptions used to simplify the design process. Table Ql(a): Normalized Fourier Coefficients V/Vpc for Bipolar PWM ma 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 n=1 1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.60 0.71 0.82 0.92 | 1.01 1.08 1.15 1.20 1.24 1.27 n = m +2 0.32 0.27 0.22 0.17 0.13 0.09 0.06 0.03 0.02 0.00 n=ms (b) Draw the frequency spectrum of the output voltage as required in (a). Indicate the values of magnitude voltages and frequencies for the fundamental and first harmonics frequencies in your drawing

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