Topic: Power Electronics
In a single-phase full-bridge inverter with square wave output, what is the amplitude of the third harmonic component if the fundamental amplitude is V?
- A. $V/3$
- B. $V/5$
- C. $V/9$
- D. $V/7$
Answer: A. $V/3$
Explanation: The Fourier series for a square wave output voltage of a single-phase full-bridge inverter is given by $v_o(t) = \sum_{n=1,3,5,...}^{\infty} \frac{4V_{dc}}{n\pi} \sin(n\omega t)$.
The amplitude of the $n^{th}$ harmonic is $V_n = \frac{4V_{dc}}{n\pi}$.
The fundamental amplitude ($n=1$) is $V_1 = \frac{4V_{dc}}{\pi} = V$.
For the third harmonic ($n=3$), the amplitude is $V_3 = \frac{4V_{dc}}{3\pi} = \frac{1}{3} \left(\frac{4V_{dc}}{\pi}\right) = \frac{V}{3}$.