Question

Example 1: Switch-mode inverter (one phase-leg, half bridge) A general analysis of the switch-mode inverter (shown in the figure below) is to be done. The switching frequency f, which is also the frequency of the triangular signal is 1450 Hz. The DC voltage, Vd, is 600 V. Output voltage is sinusoidal voltage with a frequency equal to 50 Hz. The load is connected between the inverter leg A and the dc voltage midpoint o. A+ A+ A V Find the frequency modulation ratio, mp. Calculate the output voltage (rms value of 1. harmonic), when the amplitude modulation ratio, m, is equal to 0.8? Prove that (Volpeakm, (Vd/2) Compute the rms value of the 5 most dominant harmonics of v>o (at m.-0,8), by using Table 8-1, page 207. Also indicate the frequencies at which these harmonics appear. Table 8-1 Generalized Harmonics of vAo for a Large m. 0.2 0.4 0.6 0.8 1.0 0.2 0.4 0.6 0.8 Fundamental 1.242 .15 1.006 0.818 0.601 0,016 0.0610.131 0.220 0.318 0.018 0.1900.326 0.370 0.314 0.181 0.0240.071 0.139 0.22 0.013 0.033 m, + 4 2m,+ 5 3m 0.3350.123 0.083 0.171 0.113 0.044 0.139 0.203 0.176 0.062 0.012 0.047 0.104 0.157 0.016 0.044 0.163 0.157 0.008 0.105 0.068 0.012 0.070 0.132 0.115 0.009 0.034 0.084 0.119 0.017 0.050 + 1 4m + 5 Note: (Wh/兴1-(VANudVJ is tabulated as a function of m"

Answer 1

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